lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

powerpc: Provide a way to defer perf counter work until interrupts are enabled

Browse Source 
Because 64-bit powerpc uses lazy (soft) interrupt disabling, it is
possible for a performance monitor exception to come in when the
kernel thinks interrupts are disabled (i.e. when they are
soft-disabled but hard-enabled).  In such a situation the performance
monitor exception handler might have some processing to do (such as
process wakeups) which can't be done in what is effectively an NMI
handler.

This provides a way to defer that work until interrupts get enabled,
either in raw_local_irq_restore() or by returning from an interrupt
handler to code that had interrupts enabled.  We have a per-processor
flag that indicates that there is work pending to do when interrupts
subsequently get re-enabled.  This flag is checked in the interrupt
return path and in raw_local_irq_restore(), and if it is set,
perf_counter_do_pending() is called to do the pending work.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras
2009-01-09 16:52:19 +11:00
parent d662ed2673
commit 93a6d3ce69
5 changed files with 52 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
arch/powerpc/kernel/irq.c
View File

@@ -104,6 +104,13 @@ static inline notrace void set_soft_enabled(unsigned long enable)
: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
}
#ifdef CONFIG_PERF_COUNTERS
notrace void __weak perf_counter_do_pending(void)
{
set_perf_counter_pending(0);
}
#endif
notrace void raw_local_irq_restore(unsigned long en)
{
/*
@@ -135,6 +142,9 @@ notrace void raw_local_irq_restore(unsigned long en)
iseries_handle_interrupts();
}
if (get_perf_counter_pending())
perf_counter_do_pending();
/*
* if (get_paca()->hard_enabled) return;
* But again we need to take care that gcc gets hard_enabled directly