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perf, x86: Improve the PEBS ABI 

Rename perf_event_attr::precise to perf_event_attr::precise_ip and
widen it to 2 bits. This new field describes the required precision of
the PERF_SAMPLE_IP field:

  0 - SAMPLE_IP can have arbitrary skid
  1 - SAMPLE_IP must have constant skid
  2 - SAMPLE_IP requested to have 0 skid
  3 - SAMPLE_IP must have 0 skid

And modify the Intel PEBS code accordingly. The PEBS implementation
now supports up to precise_ip == 2, where we perform the IP fixup.

Also s/PERF_RECORD_MISC_EXACT/&_IP/ to clarify its meaning, this bit
should be set for each PERF_SAMPLE_IP field known to match the actual
instruction triggering the event.

This new scheme allows for a PEBS mode that uses the buffer for more
than a single event.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-04-08 23:03:20 +02:00 committed by Ingo Molnar
parent 2b0b5c6fe9
commit ab608344bc
6 changed files with 59 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
arch/x86/kernel/cpu/perf_event.c
View File

@ -488,6 +488,21 @@ static int x86_setup_perfctr(struct perf_event *event)
static int x86_pmu_hw_config(struct perf_event *event)
{
if (event->attr.precise_ip) {
int precise = 0;
/* Support for constant skid */
if (x86_pmu.pebs)
precise++;
/* Support for IP fixup */
if (x86_pmu.lbr_nr)
precise++;
if (event->attr.precise_ip > precise)
return -EOPNOTSUPP;
}
/*
* Generate PMC IRQs:
* (keep 'enabled' bit clear for now)
@ -1780,7 +1795,7 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
}
if (regs->flags & PERF_EFLAGS_EXACT)
misc |= PERF_RECORD_MISC_EXACT;
misc |= PERF_RECORD_MISC_EXACT_IP;
return misc;
}

4
arch/x86/kernel/cpu/perf_event_intel.c
View File

@ -563,7 +563,7 @@ static void intel_pmu_disable_event(struct perf_event *event)
x86_pmu_disable_event(event);
if (unlikely(event->attr.precise))
if (unlikely(event->attr.precise_ip))
intel_pmu_pebs_disable(event);
}
@ -615,7 +615,7 @@ static void intel_pmu_enable_event(struct perf_event *event)
return;
}
if (unlikely(event->attr.precise))
if (unlikely(event->attr.precise_ip))
intel_pmu_pebs_enable(event);
__x86_pmu_enable_event(hwc, ARCH_PERFMON_EVENTSEL_ENABLE);

12
arch/x86/kernel/cpu/perf_event_intel_ds.c
View File

@ -307,7 +307,7 @@ intel_pebs_constraints(struct perf_event *event)
{
struct event_constraint *c;
if (!event->attr.precise)
if (!event->attr.precise_ip)
return NULL;
if (x86_pmu.pebs_constraints) {
@ -330,7 +330,7 @@ static void intel_pmu_pebs_enable(struct perf_event *event)
cpuc->pebs_enabled |= 1ULL << hwc->idx;
WARN_ON_ONCE(cpuc->enabled);
if (x86_pmu.intel_cap.pebs_trap)
if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1)
intel_pmu_lbr_enable(event);
}
@ -345,7 +345,7 @@ static void intel_pmu_pebs_disable(struct perf_event *event)
hwc->config |= ARCH_PERFMON_EVENTSEL_INT;
if (x86_pmu.intel_cap.pebs_trap)
if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1)
intel_pmu_lbr_disable(event);
}
@ -485,7 +485,7 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
regs.bp = pebs->bp;
regs.sp = pebs->sp;
if (intel_pmu_pebs_fixup_ip(regs))
if (event->attr.precise_ip > 1 && intel_pmu_pebs_fixup_ip(&regs))
regs.flags |= PERF_EFLAGS_EXACT;
else
regs.flags &= ~PERF_EFLAGS_EXACT;
@ -518,7 +518,7 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs)
WARN_ON_ONCE(!event);
if (!event->attr.precise)
if (!event->attr.precise_ip)
return;
n = top - at;
@ -570,7 +570,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
WARN_ON_ONCE(!event);
if (!event->attr.precise)
if (!event->attr.precise_ip)
continue;
if (__test_and_set_bit(bit, (unsigned long *)&status))

21
include/linux/perf_event.h
View File

@ -203,9 +203,19 @@ struct perf_event_attr {
enable_on_exec : 1, /* next exec enables */
task : 1, /* trace fork/exit */
watermark : 1, /* wakeup_watermark */
precise : 1, /* OoO invariant counter */
/*
* precise_ip:
*
* 0 - SAMPLE_IP can have arbitrary skid
* 1 - SAMPLE_IP must have constant skid
* 2 - SAMPLE_IP requested to have 0 skid
* 3 - SAMPLE_IP must have 0 skid
*
* See also PERF_RECORD_MISC_EXACT_IP
*/
precise_ip : 2, /* skid constraint */
__reserved_1 : 48;
__reserved_1 : 47;
union {
__u32 wakeup_events; /* wakeup every n events */
@ -296,7 +306,12 @@ struct perf_event_mmap_page {
#define PERF_RECORD_MISC_GUEST_KERNEL (4 << 0)
#define PERF_RECORD_MISC_GUEST_USER (5 << 0)
#define PERF_RECORD_MISC_EXACT (1 << 14)
/*
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
* perf_event_attr::precise_ip.
*/
#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
/*
* Reserve the last bit to indicate some extended misc field
*/

2
tools/perf/builtin-top.c
View File

@ -1021,7 +1021,7 @@ static void event__process_sample(const event_t *self,
return;
}
if (self->header.misc & PERF_RECORD_MISC_EXACT)
if (self->header.misc & PERF_RECORD_MISC_EXACT_IP)
exact_samples++;
if (event__preprocess_sample(self, session, &al, symbol_filter) < 0 ||

25
tools/perf/util/parse-events.c
View File

@ -654,10 +654,6 @@ parse_raw_event(const char **strp, struct perf_event_attr *attr)
return EVT_FAILED;
n = hex2u64(str + 1, &config);
if (n > 0) {
if (str[n+1] == 'p') {
attr->precise = 1;
n++;
}
*strp = str + n + 1;
attr->type = PERF_TYPE_RAW;
attr->config = config;
@ -692,19 +688,29 @@ static enum event_result
parse_event_modifier(const char **strp, struct perf_event_attr *attr)
{
const char *str = *strp;
int eu = 1, ek = 1, eh = 1;
int exclude = 0;
int eu = 0, ek = 0, eh = 0, precise = 0;
if (*str++ != ':')
return 0;
while (*str) {
if (*str == 'u')
if (*str == 'u') {
if (!exclude)
exclude = eu = ek = eh = 1;
eu = 0;
else if (*str == 'k')
} else if (*str == 'k') {
if (!exclude)
exclude = eu = ek = eh = 1;
ek = 0;
else if (*str == 'h')
} else if (*str == 'h') {
if (!exclude)
exclude = eu = ek = eh = 1;
eh = 0;
else
} else if (*str == 'p') {
precise++;
} else
break;
++str;
}
if (str >= *strp + 2) {
@ -712,6 +718,7 @@ parse_event_modifier(const char **strp, struct perf_event_attr *attr)
attr->exclude_user = eu;
attr->exclude_kernel = ek;
attr->exclude_hv = eh;
attr->precise_ip = precise;
return 1;
}
return 0;