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oprofile: Implement performance counter multiplexing

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The number of hardware counters is limited. The multiplexing feature
enables OProfile to gather more events than counters are provided by
the hardware. This is realized by switching between events at an user
specified time interval.

A new file (/dev/oprofile/time_slice) is added for the user to specify
the timer interval in ms. If the number of events to profile is higher
than the number of hardware counters available, the patch will
schedule a work queue that switches the event counter and re-writes
the different sets of values into it. The switching mechanism needs to
be implemented for each architecture to support multiplexing. This
patch only implements AMD CPU support, but multiplexing can be easily
extended for other models and architectures.

There are follow-on patches that rework parts of this patch.

Signed-off-by: Jason Yeh <jason.yeh@amd.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
This commit is contained in:
Jason Yeh
2009-07-08 13:49:38 +02:00
committed by Robert Richter
parent 6e63ea4b0b
commit 4d4036e0e7
12 changed files with 415 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

162
arch/x86/oprofile/nmi_int.c
View File

@@ -1,11 +1,14 @@
/**
* @file nmi_int.c
*
* @remark Copyright 2002-2008 OProfile authors
* @remark Copyright 2002-2009 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon <levon@movementarian.org>
* @author Robert Richter <robert.richter@amd.com>
* @author Barry Kasindorf <barry.kasindorf@amd.com>
* @author Jason Yeh <jason.yeh@amd.com>
* @author Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
*/
#include <linux/init.h>
@@ -24,6 +27,12 @@
#include "op_counter.h"
#include "op_x86_model.h"
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
DEFINE_PER_CPU(int, switch_index);
#endif
static struct op_x86_model_spec const *model;
static DEFINE_PER_CPU(struct op_msrs, cpu_msrs);
static DEFINE_PER_CPU(unsigned long, saved_lvtpc);
@@ -31,6 +40,13 @@ static DEFINE_PER_CPU(unsigned long, saved_lvtpc);
/* 0 == registered but off, 1 == registered and on */
static int nmi_enabled = 0;
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
extern atomic_t multiplex_counter;
#endif
struct op_counter_config counter_config[OP_MAX_COUNTER];
/* common functions */
u64 op_x86_get_ctrl(struct op_x86_model_spec const *model,
@@ -95,6 +111,11 @@ static void free_msrs(void)
per_cpu(cpu_msrs, i).counters = NULL;
kfree(per_cpu(cpu_msrs, i).controls);
per_cpu(cpu_msrs, i).controls = NULL;
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
kfree(per_cpu(cpu_msrs, i).multiplex);
per_cpu(cpu_msrs, i).multiplex = NULL;
#endif
}
}
@@ -103,6 +124,9 @@ static int allocate_msrs(void)
int success = 1;
size_t controls_size = sizeof(struct op_msr) * model->num_controls;
size_t counters_size = sizeof(struct op_msr) * model->num_counters;
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
size_t multiplex_size = sizeof(struct op_msr) * model->num_virt_counters;
#endif
int i;
for_each_possible_cpu(i) {
@@ -118,6 +142,14 @@ static int allocate_msrs(void)
success = 0;
break;
}
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
per_cpu(cpu_msrs, i).multiplex =
kmalloc(multiplex_size, GFP_KERNEL);
if (!per_cpu(cpu_msrs, i).multiplex) {
success = 0;
break;
}
#endif
}
if (!success)
@@ -126,6 +158,25 @@ static int allocate_msrs(void)
return success;
}
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
static void nmi_setup_cpu_mux(struct op_msrs const * const msrs)
{
int i;
struct op_msr *multiplex = msrs->multiplex;
for (i = 0; i < model->num_virt_counters; ++i) {
if (counter_config[i].enabled) {
multiplex[i].saved = -(u64)counter_config[i].count;
} else {
multiplex[i].addr = 0;
multiplex[i].saved = 0;
}
}
}
#endif
static void nmi_cpu_setup(void *dummy)
{
int cpu = smp_processor_id();
@@ -133,6 +184,9 @@ static void nmi_cpu_setup(void *dummy)
nmi_cpu_save_registers(msrs);
spin_lock(&oprofilefs_lock);
model->setup_ctrs(model, msrs);
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
nmi_setup_cpu_mux(msrs);
#endif
spin_unlock(&oprofilefs_lock);
per_cpu(saved_lvtpc, cpu) = apic_read(APIC_LVTPC);
apic_write(APIC_LVTPC, APIC_DM_NMI);
@@ -173,14 +227,52 @@ static int nmi_setup(void)
memcpy(per_cpu(cpu_msrs, cpu).controls,
per_cpu(cpu_msrs, 0).controls,
sizeof(struct op_msr) * model->num_controls);
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
memcpy(per_cpu(cpu_msrs, cpu).multiplex,
per_cpu(cpu_msrs, 0).multiplex,
sizeof(struct op_msr) * model->num_virt_counters);
#endif
}
}
on_each_cpu(nmi_cpu_setup, NULL, 1);
nmi_enabled = 1;
return 0;
}
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
static void nmi_cpu_save_mpx_registers(struct op_msrs *msrs)
{
unsigned int si = __get_cpu_var(switch_index);
struct op_msr *multiplex = msrs->multiplex;
unsigned int i;
for (i = 0; i < model->num_counters; ++i) {
int offset = i + si;
if (multiplex[offset].addr) {
rdmsrl(multiplex[offset].addr,
multiplex[offset].saved);
}
}
}
static void nmi_cpu_restore_mpx_registers(struct op_msrs *msrs)
{
unsigned int si = __get_cpu_var(switch_index);
struct op_msr *multiplex = msrs->multiplex;
unsigned int i;
for (i = 0; i < model->num_counters; ++i) {
int offset = i + si;
if (multiplex[offset].addr) {
wrmsrl(multiplex[offset].addr,
multiplex[offset].saved);
}
}
}
#endif
static void nmi_cpu_restore_registers(struct op_msrs *msrs)
{
struct op_msr *counters = msrs->counters;
@@ -214,6 +306,9 @@ static void nmi_cpu_shutdown(void *dummy)
apic_write(APIC_LVTPC, per_cpu(saved_lvtpc, cpu));
apic_write(APIC_LVTERR, v);
nmi_cpu_restore_registers(msrs);
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
__get_cpu_var(switch_index) = 0;
#endif
}
static void nmi_shutdown(void)
@@ -252,16 +347,15 @@ static void nmi_stop(void)
on_each_cpu(nmi_cpu_stop, NULL, 1);
}
struct op_counter_config counter_config[OP_MAX_COUNTER];
static int nmi_create_files(struct super_block *sb, struct dentry *root)
{
unsigned int i;
for (i = 0; i < model->num_counters; ++i) {
for (i = 0; i < model->num_virt_counters; ++i) {
struct dentry *dir;
char buf[4];
#ifndef CONFIG_OPROFILE_EVENT_MULTIPLEX
/* quick little hack to _not_ expose a counter if it is not
* available for use. This should protect userspace app.
* NOTE: assumes 1:1 mapping here (that counters are organized
@@ -269,6 +363,7 @@ static int nmi_create_files(struct super_block *sb, struct dentry *root)
*/
if (unlikely(!avail_to_resrv_perfctr_nmi_bit(i)))
continue;
#endif /* CONFIG_OPROFILE_EVENT_MULTIPLEX */
snprintf(buf, sizeof(buf), "%d", i);
dir = oprofilefs_mkdir(sb, root, buf);
@@ -283,6 +378,57 @@ static int nmi_create_files(struct super_block *sb, struct dentry *root)
return 0;
}
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
static void nmi_cpu_switch(void *dummy)
{
int cpu = smp_processor_id();
int si = per_cpu(switch_index, cpu);
struct op_msrs *msrs = &per_cpu(cpu_msrs, cpu);
nmi_cpu_stop(NULL);
nmi_cpu_save_mpx_registers(msrs);
/* move to next set */
si += model->num_counters;
if ((si > model->num_virt_counters) || (counter_config[si].count == 0))
per_cpu(switch_index, cpu) = 0;
else
per_cpu(switch_index, cpu) = si;
model->switch_ctrl(model, msrs);
nmi_cpu_restore_mpx_registers(msrs);
nmi_cpu_start(NULL);
}
/*
* Quick check to see if multiplexing is necessary.
* The check should be sufficient since counters are used
* in ordre.
*/
static int nmi_multiplex_on(void)
{
return counter_config[model->num_counters].count ? 0 : -EINVAL;
}
static int nmi_switch_event(void)
{
if (!model->switch_ctrl)
return -ENOSYS; /* not implemented */
if (nmi_multiplex_on() < 0)
return -EINVAL; /* not necessary */
on_each_cpu(nmi_cpu_switch, NULL, 1);
atomic_inc(&multiplex_counter);
return 0;
}
#endif
#ifdef CONFIG_SMP
static int oprofile_cpu_notifier(struct notifier_block *b, unsigned long action,
void *data)
@@ -516,12 +662,18 @@ int __init op_nmi_init(struct oprofile_operations *ops)
register_cpu_notifier(&oprofile_cpu_nb);
#endif
/* default values, can be overwritten by model */
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
__raw_get_cpu_var(switch_index) = 0;
#endif
ops->create_files = nmi_create_files;
ops->setup = nmi_setup;
ops->shutdown = nmi_shutdown;
ops->start = nmi_start;
ops->stop = nmi_stop;
ops->cpu_type = cpu_type;
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
ops->switch_events = nmi_switch_event;
#endif
if (model->init)
ret = model->init(ops);