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Date: Tue, 13 Aug 2013 13:23:01 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Andi Kleen <andi@...stfloor.org>
Cc: mingo@...nel.org, linux-kernel@...r.kernel.org, acme@...radead.org,
jolsa@...hat.com, eranian@...gle.com,
Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/4] perf, x86: Report TSX transaction abort cost as
weight
On Thu, Aug 08, 2013 at 06:15:44PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> Use the existing weight reporting facility to report the transaction
> abort cost, that is the number of cycles wasted in aborts.
> Haswell reports this in the PEBS record.
>
> This was in fact the original user for weight.
>
> This is a very useful sort key to concentrate on the most
> costly aborts and a good metric for TSX tuning.
>
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
> arch/x86/kernel/cpu/perf_event_intel_ds.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> index 3065c57..8959cc7 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> @@ -838,6 +838,12 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
> x86_pmu.intel_cap.pebs_format >= 1)
> data.addr = pebs->dla;
>
> + if ((event->attr.sample_type & PERF_SAMPLE_WEIGHT) &&
> + !fll &&
> + (x86_pmu.intel_cap.pebs_format >= 2) &&
> + pebs_hsw->tsx_tuning)
> + data.weight = pebs_hsw->tsx_tuning & 0xffffffff;
> +
> if (has_branch_stack(event))
> data.br_stack = &cpuc->lbr_stack;
How about something like the below instead? I didn't copy the !fll test
because I couldn't find why that was. Section 18.10.5.1 (Aug 2012)
doesn't mention anything like that and I figure the reason bits would be
0 when the thing isn't appropriate.
---
arch/x86/kernel/cpu/perf_event_intel_ds.c | 63 +++++++++++++++++++++----------
1 file changed, 44 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 3065c57..52cb1fa 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -178,20 +178,15 @@ struct pebs_record_nhm {
u64 status, dla, dse, lat;
};
-/*
- * Same as pebs_record_nhm, with two additional fields.
- */
struct pebs_record_hsw {
- struct pebs_record_nhm nhm;
- /*
- * Real IP of the event. In the Intel documentation this
- * is called eventingrip.
- */
- u64 real_ip;
- /*
- * TSX tuning information field: abort cycles and abort flags.
- */
- u64 tsx_tuning;
+ u64 flags, ip;
+ u64 ax, bx, cx, dx;
+ u64 si, di, bp, sp;
+ u64 r8, r9, r10, r11;
+ u64 r12, r13, r14, r15;
+ u64 status, dla, dse, lat;
+ u64 real_ip; /* the actual eventing ip */
+ u64 tsx_tuning; /* TSX abort cycles and flags */
};
void init_debug_store_on_cpu(int cpu)
@@ -759,16 +754,41 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
return 0;
}
+union hsw_tsx_tuning {
+ struct {
+ u64 cycles_last_block : 32,
+ hle_abort : 1,
+ rtm_abort : 1,
+ ins_abort : 1,
+ non_ins_abort : 1,
+ retry : 1,
+ mem_data_conflict : 1,
+ capacity : 1;
+ } bits;
+ u64 value;
+};
+
+static inline u64 intel_hsw_weight(struct pebs_record_hsw *pebs)
+{
+ u64 weight = 0;
+
+ if (pebs->tsx_tuning) {
+ union hsw_tsx_tuning tsx = { .value = pebs->tsx_tuning };
+ weight = tsx.bits.cycles_last_block;
+ }
+
+ return weight;
+}
+
static void __intel_pmu_pebs_event(struct perf_event *event,
struct pt_regs *iregs, void *__pebs)
{
/*
- * We cast to pebs_record_nhm to get the load latency data
- * if extra_reg MSR_PEBS_LD_LAT_THRESHOLD used
+ * We cast to the biggest PEBS record and are careful not
+ * to access out-of-bounds members.
*/
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
- struct pebs_record_nhm *pebs = __pebs;
- struct pebs_record_hsw *pebs_hsw = __pebs;
+ struct pebs_record_hsw *pebs = __pebs;
struct perf_sample_data data;
struct pt_regs regs;
u64 sample_type;
@@ -826,8 +846,9 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
regs.bp = pebs->bp;
regs.sp = pebs->sp;
+
if (event->attr.precise_ip > 1 && x86_pmu.intel_cap.pebs_format >= 2) {
- regs.ip = pebs_hsw->real_ip;
+ regs.ip = pebs->real_ip;
regs.flags |= PERF_EFLAGS_EXACT;
} else if (event->attr.precise_ip > 1 && intel_pmu_pebs_fixup_ip(®s))
regs.flags |= PERF_EFLAGS_EXACT;
@@ -835,9 +856,13 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
regs.flags &= ~PERF_EFLAGS_EXACT;
if ((event->attr.sample_type & PERF_SAMPLE_ADDR) &&
- x86_pmu.intel_cap.pebs_format >= 1)
+ x86_pmu.intel_cap.pebs_format >= 1)
data.addr = pebs->dla;
+ if ((event->attr.sample_type & PERF_SAMPLE_WEIGHT) &&
+ x86_pmu.intel_cap.pebs_format >= 2)
+ data.weight = intel_hsw_weight(pebs);
+
if (has_branch_stack(event))
data.br_stack = &cpuc->lbr_stack;
--
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