Commit Graph

107 Commits

Author SHA1 Message Date
Adrian Hunter
c73deb6aec perf/x86: Add ability to calculate TSC from perf sample timestamps
For modern CPUs, perf clock is directly related to TSC.  TSC
can be calculated from perf clock and vice versa using a simple
calculation.  Two of the three componenets of that calculation
are already exported in struct perf_event_mmap_page.  This patch
exports the third.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1372425741-1676-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-23 12:17:45 +02:00
Paul Gortmaker
148f9bb877 x86: delete __cpuinit usage from all x86 files
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-14 19:36:56 -04:00
Feng Tang
82f9c080b2 x86: tsc: Add support for new S3_NONSTOP feature
Add support for new S3_NONSTOP feature

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-03-15 16:51:18 -07:00
Thomas Gleixner
90889a635a Merge branch 'fortglx/3.9/time' of git://git.linaro.org/people/jstultz/linux into timers/core
Trivial conflict in arch/x86/Kconfig

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-02-04 11:03:03 +01:00
Bernd Faust
2353b47bff Round the calculated scale factor in set_cyc2ns_scale()
During some experiments with an external clock (in a FPGA), we saw that
the TSC clock drifted approx. 2.5ms per second.

This drift was caused by the current way of calculating the scale.
In our case cpu_khz had a value of 3292725. This resulted in a scale
value of 310. But when doing the calculation by hand it shows that the
actual value is 310.9886188491, so a value of 311 would be more precise.

With this change the value is rounded.

Signed-off-by: Bernd Faust <berndfaust@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-01-15 18:16:07 -08:00
David Vrabel
ce37f40033 x86: Allow tracing of functions in arch/x86/kernel/rtc.c
Move native_read_tsc() to tsc.c to allow profiling to be
re-enabled for rtc.c.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1349698050-6560-1-git-send-email-david.vrabel@citrix.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-10-24 13:14:22 +02:00
Joe Perches
c767a54ba0 x86/debug: Add KERN_<LEVEL> to bare printks, convert printks to pr_<level>
Use a more current logging style:

 - Bare printks should have a KERN_<LEVEL> for consistency's sake
 - Add pr_fmt where appropriate
 - Neaten some macro definitions
 - Convert some Ok output to OK
 - Use "%s: ", __func__ in pr_fmt for summit
 - Convert some printks to pr_<level>

Message output is not identical in all cases.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: levinsasha928@gmail.com
Link: http://lkml.kernel.org/r/1337655007.24226.10.camel@joe2Laptop
[ merged two similar patches, tidied up the changelog ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-06-06 09:17:22 +02:00
Linus Torvalds
bcd550745f Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer core updates from Thomas Gleixner.

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ia64: vsyscall: Add missing paranthesis
  alarmtimer: Don't call rtc_timer_init() when CONFIG_RTC_CLASS=n
  x86: vdso: Put declaration before code
  x86-64: Inline vdso clock_gettime helpers
  x86-64: Simplify and optimize vdso clock_gettime monotonic variants
  kernel-time: fix s/then/than/ spelling errors
  time: remove no_sync_cmos_clock
  time: Avoid scary backtraces when warning of > 11% adj
  alarmtimer: Make sure we initialize the rtctimer
  ntp: Fix leap-second hrtimer livelock
  x86, tsc: Skip refined tsc calibration on systems with reliable TSC
  rtc: Provide flag for rtc devices that don't support UIE
  ia64: vsyscall: Use seqcount instead of seqlock
  x86: vdso: Use seqcount instead of seqlock
  x86: vdso: Remove bogus locking in update_vsyscall_tz()
  time: Remove bogus comments
  time: Fix change_clocksource locking
  time: x86: Fix race switching from vsyscall to non-vsyscall clock
2012-03-29 14:16:48 -07:00
Linus Torvalds
2e7580b0e7 Merge branch 'kvm-updates/3.4' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Avi Kivity:
 "Changes include timekeeping improvements, support for assigning host
  PCI devices that share interrupt lines, s390 user-controlled guests, a
  large ppc update, and random fixes."

This is with the sign-off's fixed, hopefully next merge window we won't
have rebased commits.

* 'kvm-updates/3.4' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits)
  KVM: Convert intx_mask_lock to spin lock
  KVM: x86: fix kvm_write_tsc() TSC matching thinko
  x86: kvmclock: abstract save/restore sched_clock_state
  KVM: nVMX: Fix erroneous exception bitmap check
  KVM: Ignore the writes to MSR_K7_HWCR(3)
  KVM: MMU: make use of ->root_level in reset_rsvds_bits_mask
  KVM: PMU: add proper support for fixed counter 2
  KVM: PMU: Fix raw event check
  KVM: PMU: warn when pin control is set in eventsel msr
  KVM: VMX: Fix delayed load of shared MSRs
  KVM: use correct tlbs dirty type in cmpxchg
  KVM: Allow host IRQ sharing for assigned PCI 2.3 devices
  KVM: Ensure all vcpus are consistent with in-kernel irqchip settings
  KVM: x86 emulator: Allow PM/VM86 switch during task switch
  KVM: SVM: Fix CPL updates
  KVM: x86 emulator: VM86 segments must have DPL 3
  KVM: x86 emulator: Fix task switch privilege checks
  arch/powerpc/kvm/book3s_hv.c: included linux/sched.h twice
  KVM: x86 emulator: correctly mask pmc index bits in RDPMC instruction emulation
  KVM: mmu_notifier: Flush TLBs before releasing mmu_lock
  ...
2012-03-28 14:35:31 -07:00
Marcelo Tosatti
b74f05d61b x86: kvmclock: abstract save/restore sched_clock_state
Upon resume from hibernation, CPU 0's hvclock area contains the old
values for system_time and tsc_timestamp. It is necessary for the
hypervisor to update these values with uptodate ones before the CPU uses
them.

Abstract TSC's save/restore sched_clock_state functions and use
restore_state to write to KVM_SYSTEM_TIME MSR, forcing an update.

Also move restore_sched_clock_state before __restore_processor_state,
since the later calls CONFIG_LOCK_STAT's lockstat_clock (also for TSC).
Thanks to Igor Mammedov for tracking it down.

Fixes suspend-to-disk with kvmclock.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-03-20 12:37:45 +02:00
Alok Kataria
57779dc2b3 x86, tsc: Skip refined tsc calibration on systems with reliable TSC
While running the latest Linux as guest under VMware in highly
over-committed situations, we have seen cases when the refined TSC
algorithm fails to get a valid tsc_start value in
tsc_refine_calibration_work from multiple attempts. As a result the
kernel keeps on scheduling the tsc_irqwork task for later. Subsequently
after several attempts when it gets a valid start value it goes through
the refined calibration and either bails out or uses the new results.
Given that the kernel originally read the TSC frequency from the
platform, which is the best it can get, I don't think there is much
value in refining it.

So  for systems which get the TSC frequency from the platform we
should skip the refined tsc algorithm.

We can use the TSC_RELIABLE cpu cap flag to detect this, right now it is
set only on VMware and for Moorestown Penwell both of which have there
own TSC calibration methods.

Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Dirk Brandewie <dirk.brandewie@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
[jstultz: Reworked to simply not schedule the refining work,
rather then scheduling the work and bombing out later]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-03-15 18:23:11 -07:00
Salman Qazi
9993bc635d sched/x86: Fix overflow in cyc2ns_offset
When a machine boots up, the TSC generally gets reset.  However,
when kexec is used to boot into a kernel, the TSC value would be
carried over from the previous kernel.  The computation of
cycns_offset in set_cyc2ns_scale is prone to an overflow, if the
machine has been up more than 208 days prior to the kexec.  The
overflow happens when we multiply *scale, even though there is
enough room to store the final answer.

We fix this issue by decomposing tsc_now into the quotient and
remainder of division by CYC2NS_SCALE_FACTOR and then performing
the multiplication separately on the two components.

Refactor code to share the calculation with the previous
fix in __cycles_2_ns().

Signed-off-by: Salman Qazi <sqazi@google.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Turner <pjt@google.com>
Cc: john stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20120310004027.19291.88460.stgit@dungbeetle.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-13 16:27:51 +01:00
H. Peter Anvin
282f445a77 Merge remote-tracking branch 'linus/master' into x86/urgent 2012-01-19 12:56:50 -08:00
Linus Torvalds
68f30fbee1 x86, tsc: Fix SMI induced variation in quick_pit_calibrate()
pit_expect_msb() returns success wrongly in the below SMI scenario:

a. pit_verify_msb() has not yet seen the MSB transition.

b. we are close to the MSB transition though and got a SMI immediately after
   returning from pit_verify_msb() which didn't see the MSB transition. PIT MSB
   transition has happened somewhere during SMI execution.

c. returned from SMI and we noted down the 'tsc', saw the pit MSB change now and
   exited the loop to calculate 'deltatsc'. Instead of noting the TSC at the MSB
   transition, we are way off because of the SMI.  And as the SMI happened
   between the pit_verify_msb() and before the 'tsc' is recorded in the
   for loop, 'delattsc' (d1/d2 in quick_pit_calibrate()) will be small and
   quick_pit_calibrate() will not notice this error.

Depending on whether SMI disturbance happens while computing d1 or d2, we will
see the TSC calibrated value smaller or bigger than the expected value. As a
result, in a cluster we were seeing a variation of approximately +/- 20MHz in
the calibrated values, resulting in NTP failures.

  [ As far as the SMI source is concerned, this is a periodic SMI that gets
    disabled after ACPI is enabled by the OS. But the TSC calibration happens
    before the ACPI is enabled. ]

To address this, change pit_expect_msb() so that

 - the 'tsc' is the TSC in between the two reads that read the MSB
change from the PIT (same as before)

 - the 'delta' is the difference in TSC from *before* the MSB changed
to *after* the MSB changed.

Now the delta is twice as big as before (it covers four PIT accesses,
roughly 4us) and quick_pit_calibrate() will loop a bit longer to get
the calibrated value with in the 500ppm precision. As the delta (d1/d2)
covers four PIT accesses, actual calibrated result might be closer to
250ppm precision.

As the loop now takes longer to stabilize, double MAX_QUICK_PIT_MS to 50.

SMI disturbance will showup as much larger delta's and the loop will take
longer than usual for the result to be with in the accepted precision. Or will
fallback to slow PIT calibration if it takes more than 50msec.

Also while we are at this, remove the calibration correction that aims to
get the result to the middle of the error bars. We really don't know which
direction to correct into, so remove it.

Reported-and-tested-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1326843337.5291.4.camel@sbsiddha-mobl2
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2012-01-17 15:46:51 -08:00
Linus Torvalds
9fc5c3e323 Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/intel config: Fix the APB_TIMER selection
  x86/mrst: Add additional debug prints for pb_keys
  x86/intel config: Revamp configuration to allow for Moorestown and Medfield
  x86/intel/scu/ipc: Match the changes in the x86 configuration
  x86/apb: Fix configuration constraints
  x86: Fix INTEL_MID silly
  x86/Kconfig: Cyclone-timer depends on x86-summit
  x86: Reduce clock calibration time during slave cpu startup
  x86/config: Revamp configuration for MID devices
  x86/sfi: Kill the IRQ as id hack
2012-01-11 19:13:40 -08:00
Thomas Gleixner
0518469d0a Merge branch 'fortglx/3.3/tip/timers/core' of git://git.linaro.org/people/jstultz/linux into timers/core 2011-12-05 22:13:49 +01:00
Suresh Siddha
28a00184be x86, tsc: Skip TSC synchronization checks for tsc=reliable
tsc=reliable boot parameter is supposed to skip all the TSC
stablility checks during boot time.

On a 8-socket system where we want to run an experiment with the
"tsc=reliable" boot option, TSC synchronization checks are not
getting skipped and marking the TSC as not stable.

Check for tsc_clocksource_reliable (which is set via
tsc=reliable or for platforms supporting synthetic TSC_RELIABLE
feature bit etc) and when set, skip the TSC synchronization
tests during boot.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1320446537.15071.14.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-05 18:00:31 +01:00
Jack Steiner
b565201cf7 x86: Reduce clock calibration time during slave cpu startup
Reduce the startup time for slave cpus.

Adds hooks for an arch-specific function for clock calibration.
These hooks are used on x86.  If a newly started cpu has the
same phys_proc_id as a core already active, uses the TSC for the
delay loop and has a CONSTANT_TSC, use the already-calculated
value of loops_per_jiffy.

This patch reduces the time required to start slave cpus on a
4096 cpu system from: 465 sec OLD 62 sec NEW

This reduces boot time on a 4096p system by almost 7 minutes.
Nice...

Signed-off-by: Jack Steiner <steiner@sgi.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
[fix CONFIG_SMP=n build]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-05 17:12:43 +01:00
Deepak Saxena
b7743970b0 time: x86: Remove CLOCK_TICK_RATE from tsc code
The tsc code uses CLOCK_TICK_RATE which on x86
is defined to just be the same as PIT_TICK_RATE.
This patch updates the code use the later
as we want to depecrate and remove the global
CLOCK_TICK_RATE symbol.

Signed-off-by: Deepak Saxena <dsaxena@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-11-21 19:00:56 -08:00
Linus Torvalds
b4db920c7f Merge branches 'x86-detect-hyper-for-linus', 'x86-fpu-for-linus', 'x86-kexec-for-linus', 'x86-platform-for-linus', 'x86-quirks-for-linus', 'x86-tsc-for-linus' and 'x86-smpboot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-detect-hyper-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, hyper: Change hypervisor detection order

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86-32, fpu: Fix DNA exception during check_fpu()

* 'x86-kexec-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  kexec, x86: Fix incorrect jump back address if not preserving context

* 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, config: Introduce an INTEL_MID configuration

* 'x86-quirks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, quirks: Use pci_dev->revision

* 'x86-tsc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: tsc: Remove unneeded DMI-based blacklisting

* 'x86-smpboot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, boot: Wait for boot cpu to show up if nr_cpus limit is about to hit
2011-07-23 10:38:21 -07:00
Andy Lutomirski
98d0ac38ca x86-64: Move vread_tsc and vread_hpet into the vDSO
The vsyscall page now consists entirely of trap instructions.

Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/637648f303f2ef93af93bae25186e9a1bea093f5.1310639973.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-14 17:57:05 -07:00
Andy Lutomirski
433bd805e5 clocksource: Replace vread with generic arch data
The vread field was bloating struct clocksource everywhere except
x86_64, and I want to change the way this works on x86_64, so let's
split it out into per-arch data.

Cc: x86@kernel.org
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: linux-ia64@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/3ae5ec76a168eaaae63f08a2a1060b91aa0b7759.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-13 11:23:12 -07:00
Tero Roponen
df049672dd x86: tsc: Remove unneeded DMI-based blacklisting
The blacklist was added in response to my bug report
(http://lkml.org/lkml/2006/1/19/362) and has never
contained more than the one entry describing my old
now dead ThinkPad 380XD laptop. As found out later
(http://lkml.org/lkml/2007/11/29/50), this special
treatment has been unnecessary for a long time, so
it can be removed.

Signed-off-by: Tero Roponen <tero.roponen@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-05-31 23:19:51 -07:00
Andy Lutomirski
44259b1abf x86-64: Move vread_tsc into a new file with sensible options
vread_tsc is short and hot, and it's userspace code so the usual
reasons to enable -pg and turn off sibling calls don't apply.

(OK, turning off sibling calls has no effect.  But it might
someday...)

As an added benefit, tsc.c is profilable now.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C99c6d7f5efa3ccb65b4ac6eb443e1ab7bad47d7b.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 14:51:29 +02:00
Andy Lutomirski
3729db5ca2 x86-64: Don't generate cmov in vread_tsc
vread_tsc checks whether rdtsc returns something less than
cycle_last, which is an extremely predictable branch.  GCC likes
to generate a cmov anyway, which is several cycles slower than
a predicted branch.  This saves a couple of nanoseconds.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C561280649519de41352fcb620684dfb22bad6bac.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 14:51:28 +02:00
Andy Lutomirski
057e6a8c66 x86-64: Remove unnecessary barrier in vread_tsc
RDTSC is completely unordered on modern Intel and AMD CPUs.  The
Intel manual says that lfence;rdtsc causes all previous instructions
to complete before the tsc is read, and the AMD manual says to use
mfence;rdtsc to do the same thing.

From a decent amount of testing [1] this is enough to make rdtsc
be ordered with respect to subsequent loads across a wide variety
of CPUs.

On Sandy Bridge (i7-2600), this improves a loop of
clock_gettime(CLOCK_MONOTONIC) by more than 5 ns/iter.

[1] https://lkml.org/lkml/2011/4/18/350

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C1c158b9d74338aa5361f96dd473d0e6a58235302.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 14:51:28 +02:00
Andy Lutomirski
8c49d9a74b x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are
currently a bit of a mess.  They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.

This changes them all to use a common mechanism.  All of them are
delcared in vvar.h with a fixed address (validated by the linker
script).  In the kernel (as before), they look like ordinary
read-write variables.  In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.

The vdso is now loaded verbatim into memory without any fixups.  As a
side bonus, access from the vdso is faster because a level of
indirection is removed.

While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-24 14:51:28 +02:00
Lucas De Marchi
0d2eb44f63 x86: Fix common misspellings
They were generated by 'codespell' and then manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-03-18 10:39:30 +01:00
Linus Torvalds
f9ee7f60d6 Merge branches 'core-fixes-for-linus', 'x86-fixes-for-linus', 'timers-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: avoid pointless blocked-task warnings
  rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
  rtmutex: Fix comment about why new_owner can be NULL in wake_futex_pi()

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, olpc: Add missing Kconfig dependencies
  x86, mrst: Set correct APB timer IRQ affinity for secondary cpu
  x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
  x86, ia64, acpi: Clean up x86-ism in drivers/acpi/numa.c

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timekeeping: Make local variables static
  time: Rename misnamed minsec argument of clocks_calc_mult_shift()

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: Remove syscall_exit_fields
  tracing: Only process module tracepoints once
  perf record: Add "nodelay" mode, disabled by default
  perf sched: Fix list of events, dropping unsupported ':r' modifier
  Revert "perf tools: Emit clearer message for sys_perf_event_open ENOENT return"
  perf top: Fix annotate segv
  perf evsel: Fix order of event list deletion
2011-01-15 12:45:00 -08:00
John Stultz
62627bec8a x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
Konrad Wilk reported that the new delayed calibration crashes with a
divide by zero on Xen. The reason is that Xen sets the pmtimer
address, but reading from it returns 0xffffff. That results in the
ref_start and ref_stop value being the same, so the delta is zero
which causes the divide by zero later in the calculation.

The conditional (!hpet && !ref_start && !ref_stop) which sanity checks
the calibration reference values doesn't really make sense. If the
refs are null, but hpet is on, we still want to break out.

The div by zero would be possible to trigger by chance if both reads
from the hardware provided the exact same value (due to hardware
wrapping).

So checking if both the ref values are the same should handle if we
don't have hardware (both null) or if they are the same value (either by
invalid hardware, or by chance), avoiding the div by zero issue.

[ tglx: Applied the same fix to native_calibrate_tsc() where this
  	check was copied from ]

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1295024788-15619-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-14 18:28:01 +01:00
Linus Torvalds
16ee8db6a9 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Fix Moorestown VRTC fixmap placement
  x86/gpio: Implement x86 gpio_to_irq convert function
  x86, UV: Fix APICID shift for Westmere processors
  x86: Use PCI method for enabling AMD extended config space before MSR method
  x86: tsc: Prevent delayed init if initial tsc calibration failed
  x86, lapic-timer: Increase the max_delta to 31 bits
  x86: Fix sparse non-ANSI function warnings in smpboot.c
  x86, numa: Fix CONFIG_DEBUG_PER_CPU_MAPS without NUMA emulation
  x86, AMD, PCI: Add AMD northbridge PCI device id for CPU families 12h and 14h
  x86, numa: Fix cpu to node mapping for sparse node ids
  x86, numa: Fake node-to-cpumask for NUMA emulation
  x86, numa: Fake apicid and pxm mappings for NUMA emulation
  x86, numa: Avoid compiling NUMA emulation functions without CONFIG_NUMA_EMU
  x86, numa: Reduce minimum fake node size to 32M

Fix up trivial conflict in arch/x86/kernel/apic/x2apic_uv_x.c
2011-01-11 11:11:46 -08:00
Thomas Gleixner
29fe359ca2 x86: tsc: Prevent delayed init if initial tsc calibration failed
commit a8760ec (x86: Check tsc available/disabled in the delayed init
function) missed to prevent the setup of the delayed init function in
case the initial tsc calibration failed. This results in the same
divide by zero bug as we have seen without the tsc disabled check.

Skip the delayed work setup when tsc_khz (the initial calibration
value) is 0.

Bisected-and-tested-by: Kirill A. Shutemov <kas@openvz.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-11 11:48:39 +01:00
Linus Torvalds
72eb6a7914 Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
  gameport: use this_cpu_read instead of lookup
  x86: udelay: Use this_cpu_read to avoid address calculation
  x86: Use this_cpu_inc_return for nmi counter
  x86: Replace uses of current_cpu_data with this_cpu ops
  x86: Use this_cpu_ops to optimize code
  vmstat: User per cpu atomics to avoid interrupt disable / enable
  irq_work: Use per cpu atomics instead of regular atomics
  cpuops: Use cmpxchg for xchg to avoid lock semantics
  x86: this_cpu_cmpxchg and this_cpu_xchg operations
  percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
  percpu,x86: relocate this_cpu_add_return() and friends
  connector: Use this_cpu operations
  xen: Use this_cpu_inc_return
  taskstats: Use this_cpu_ops
  random: Use this_cpu_inc_return
  fs: Use this_cpu_inc_return in buffer.c
  highmem: Use this_cpu_xx_return() operations
  vmstat: Use this_cpu_inc_return for vm statistics
  x86: Support for this_cpu_add, sub, dec, inc_return
  percpu: Generic support for this_cpu_add, sub, dec, inc_return
  ...

Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
2011-01-07 17:02:58 -08:00
Tejun Heo
0a3aee0da4 x86: Use this_cpu_ops to optimize code
Go through x86 code and replace __get_cpu_var and get_cpu_var
instances that refer to a scalar and are not used for address
determinations.

Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-12-30 12:20:28 +01:00
Thomas Gleixner
a8760eca6c x86: Check tsc available/disabled in the delayed init function
The delayed TSC init function does not check whether the system has no
TSC or TSC is disabled at the kernel command line, which results in a
crash in the work queue based extended calibration due to division by
zero because the basic calibration never happened.

Add the missing checks and do not touch TSC when not available or
disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@us.ibm.com>
2010-12-13 11:35:05 +01:00
John Stultz
08ec0c58fb x86: Improve TSC calibration using a delayed workqueue
Boot to boot the TSC calibration may vary by quite a large amount.

While normal variance of 50-100ppm can easily be seen, the quick
calibration code only requires 500ppm accuracy, which is the limit
of what NTP can correct for.

This can cause problems for systems being used as NTP servers, as
every time they reboot it can take hours for them to calculate the
new drift error caused by the calibration.

The classic trade-off here is calibration accuracy vs slow boot times,
as during the calibration nothing else can run.

This patch uses a delayed workqueue  to calibrate the TSC over the
period of a second. This allows very accurate calibration (in my
tests only varying by 1khz or 0.4ppm boot to boot). Additionally this
refined calibration step does not block the boot process, and only
delays the TSC clocksoure registration by a few seconds in early boot.
If the refined calibration strays 1% from the early boot calibration
value, the system will fall back to already calculated early boot
calibration.

Credit to Andi Kleen who suggested using a timer quite awhile back,
but I dismissed it thinking the timer calibration would be done after
the clocksource was registered (which would break things). Forgive
me for my short-sightedness.

This patch has worked very well in my testing, but TSC hardware is
quite varied so it would probably be good to get some extended
testing, possibly pushing inclusion out to 2.6.39.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1289003985-29060-1-git-send-email-johnstul@us.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@elte.hu>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Clark Williams <williams@redhat.com>
CC: Andi Kleen <andi@firstfloor.org>
2010-12-02 16:48:37 -08:00
John Stultz
b0f969009f Merge remote branch 'tip/x86/tsc' into fortglx/2.6.38/tip/x86/tsc
Conflicts:
	Documentation/kernel-parameters.txt
2010-12-02 16:47:52 -08:00
Linus Torvalds
2f0384e5fc Merge branch 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, amd_nb: Enable GART support for AMD family 0x15 CPUs
  x86, amd: Use compute unit information to determine thread siblings
  x86, amd: Extract compute unit information for AMD CPUs
  x86, amd: Add support for CPUID topology extension of AMD CPUs
  x86, nmi: Support NMI watchdog on newer AMD CPU families
  x86, mtrr: Assume SYS_CFG[Tom2ForceMemTypeWB] exists on all future AMD CPUs
  x86, k8: Rename k8.[ch] to amd_nb.[ch] and CONFIG_K8_NB to CONFIG_AMD_NB
  x86, k8-gart: Decouple handling of garts and northbridges
  x86, cacheinfo: Fix dependency of AMD L3 CID
  x86, kvm: add new AMD SVM feature bits
  x86, cpu: Fix allowed CPUID bits for KVM guests
  x86, cpu: Update AMD CPUID feature bits
  x86, cpu: Fix renamed, not-yet-shipping AMD CPUID feature bit
  x86, AMD: Remove needless CPU family check (for L3 cache info)
  x86, tsc: Remove CPU frequency calibration on AMD
2010-10-21 13:01:08 -07:00
Venkatesh Pallipadi
e82b8e4ea4 x86: Add IRQ_TIME_ACCOUNTING
This patch adds IRQ_TIME_ACCOUNTING option on x86 and runtime enables it
when TSC is enabled.

This change just enables fine grained irq time accounting, isn't used yet.
Following patches use it for different purposes.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-6-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-18 20:52:25 +02:00
H. Peter Anvin
86ffb08519 Merge remote branch 'origin/x86/cpu' into x86/amd-nb 2010-10-01 16:18:11 -07:00
Peter Zijlstra
5ee5e97ee9 x86, tsc: Fix a preemption leak in restore_sched_clock_state()
A real life genuine preemption leak..

Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-09-10 18:17:45 -07:00
Borislav Petkov
acf01734b1 x86, tsc: Remove CPU frequency calibration on AMD
6b37f5a20c introduced the CPU frequency
calibration code for AMD CPUs whose TSCs didn't increment with the
core's P0 frequency. From F10h, revB onward, however, the TSC increment
rate is denoted by MSRC001_0015[24] and when this bit is set (which
should be done by the BIOS) the TSC increments with the P0 frequency
so the calibration is not needed and booting can be a couple of mcecs
faster on those machines.

Besides, there should be virtually no machines out there which don't
have this bit set, therefore this calibration can be safely removed. It
is a shaky hack anyway since it assumes implicitly that the core is in
P0 when BIOS hands off to the OS, which might not always be the case.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100825162823.GE26438@aftab>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-08-25 13:32:52 -07:00
Suresh Siddha
cd7240c0b9 x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states
TSC's get reset after suspend/resume (even on cpu's with invariant TSC
which runs at a constant rate across ACPI P-, C- and T-states). And in
some systems BIOS seem to reinit TSC to arbitrary large value (still
sync'd across cpu's) during resume.

This leads to a scenario of scheduler rq->clock (sched_clock_cpu()) less
than rq->age_stamp (introduced in 2.6.32). This leads to a big value
returned by scale_rt_power() and the resulting big group power set by the
update_group_power() is causing improper load balancing between busy and
idle cpu's after suspend/resume.

This resulted in multi-threaded workloads (like kernel-compilation) go
slower after suspend/resume cycle on core i5 laptops.

Fix this by recomputing cyc2ns_offset's during resume, so that
sched_clock() continues from the point where it was left off during
suspend.

Reported-by: Florian Pritz <flo@xssn.at>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org> # [v2.6.32+]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-08-20 14:59:02 +02:00
John Stultz
f12a15be63 x86: Convert common clocksources to use clocksource_register_hz/khz
This converts the most common of the x86 clocksources over to use
clocksource_register_hz/khz.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-11-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-07-27 12:40:55 +02:00
Jiri Kosina
318ae2edc3 Merge branch 'for-next' into for-linus
Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c
2010-03-08 16:55:37 +01:00
Linus Torvalds
e56425b135 Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  posix-timers.c: Don't export local functions
  clocksource: start CMT at clocksource resume
  clocksource: add suspend callback
  clocksource: add argument to resume callback
  ntp: Cleanup xtime references in ntp.c
  ntp: Make time_esterror and time_maxerror static
2010-03-01 08:48:25 -08:00
Daniel Mack
3ad2f3fbb9 tree-wide: Assorted spelling fixes
In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-02-09 11:13:56 +01:00
Magnus Damm
17622339af clocksource: add argument to resume callback
Pass the clocksource as an argument to the clocksource resume callback. 
Needed so we can point out which CMT channel the sh_cmt.c driver shall
resume.

Signed-off-by: Magnus Damm <damm@opensource.se>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-02-05 14:54:10 +01:00
Thadeu Lima de Souza Cascardo
00097c4fdf x86, trivial: Fix grammo in tsc comment about Geode TSC reliability
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: marcelo@kvack.org
Cc: dilinger@collabora.co.uk
Cc: trivial@kernel.org
LKML-Reference: <1263764685-9871-1-git-send-email-cascardo@holoscopio.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-18 09:01:39 +01:00
Pallipadi, Venkatesh
6c56ccecf0 x86: Reenable TSC sync check at boot, even with NONSTOP_TSC
Commit 83ce4009 did the following change
If the TSC is constant and non-stop, also set it reliable.

But, there seems to be few systems that will end up with TSC warp across
sockets, depending on how the cpus come out of reset. Skipping TSC sync
test on such systems may result in time inconsistency later.

So, reenable TSC sync test even on constant and non-stop TSC systems.
Set, sched_clock_stable to 1 by default and reset it in
mark_tsc_unstable, if TSC sync fails.

This change still gives perf benefit mentioned in 83ce4009 for systems
where TSC is reliable.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-12-17 14:44:35 -08:00