| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CAM9d7cjMHcz_hunqKLtuKCK2BaX7NzXfE1tWCiSTxEEHz8_Jbg@mail.gmail.com>
Date: Wed, 6 Jan 2021 16:38:01 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Leo Yan <leo.yan@...aro.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Andi Kleen <ak@...ux.intel.com>,
Ian Rogers <irogers@...gle.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Joe Mario <jmario@...hat.com>, David Ahern <dsahern@...il.com>,
Don Zickus <dzickus@...hat.com>, Al Grant <Al.Grant@....com>,
James Clark <james.clark@....com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 01/11] perf c2c: Add dimensions for total load hit
Hi,
On Sun, Dec 13, 2020 at 10:39 PM Leo Yan <leo.yan@...aro.org> wrote:
>
> Arm SPE trace data doesn't support HITM, but we still want to explore
> "perf c2c" tool to analyze cache false sharing. If without HITM tag,
> the tool cannot give out accurate result for cache false sharing, a
> candidate solution is to sort the total load operations and connect with
> the threads info, e.g. if multiple threads hit the same cache line for
> many times, this can give out the hint that it's likely to cause cache
> false sharing issue.
>
> Unlike having HITM tag, the proposed solution is not accurate and might
> introduce false positive reporting, but it's a pragmatic approach for
> detecting false sharing if memory event doesn't support HITM.
>
> To sort with the cache line hit, this patch adds dimensions for total
> load hit and the associated percentage calculation.
>
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
> tools/perf/builtin-c2c.c | 112 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 112 insertions(+)
>
> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index c5babeaa3b38..3d5a2dc8b4fd 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
> @@ -615,6 +615,47 @@ tot_hitm_cmp(struct perf_hpp_fmt *fmt __maybe_unused,
> return tot_hitm_left - tot_hitm_right;
> }
>
> +#define TOT_LD_HIT(stats) \
> + ((stats)->ld_fbhit + \
> + (stats)->ld_l1hit + \
> + (stats)->ld_l2hit + \
> + (stats)->ld_llchit + \
> + (stats)->lcl_hitm + \
> + (stats)->rmt_hitm + \
> + (stats)->rmt_hit)
It doesn't need to be a macro, why not use a static inline function?
Thanks,
Namhyung
> +
> +static int tot_ld_hit_entry(struct perf_hpp_fmt *fmt,
> + struct perf_hpp *hpp,
> + struct hist_entry *he)
> +{
> + struct c2c_hist_entry *c2c_he;
> + int width = c2c_width(fmt, hpp, he->hists);
> + unsigned int tot_hit;
> +
> + c2c_he = container_of(he, struct c2c_hist_entry, he);
> + tot_hit = TOT_LD_HIT(&c2c_he->stats);
> +
> + return scnprintf(hpp->buf, hpp->size, "%*u", width, tot_hit);
> +}
> +
> +static int64_t tot_ld_hit_cmp(struct perf_hpp_fmt *fmt __maybe_unused,
> + struct hist_entry *left,
> + struct hist_entry *right)
> +{
> + struct c2c_hist_entry *c2c_left;
> + struct c2c_hist_entry *c2c_right;
> + uint64_t tot_hit_left;
> + uint64_t tot_hit_right;
> +
> + c2c_left = container_of(left, struct c2c_hist_entry, he);
> + c2c_right = container_of(right, struct c2c_hist_entry, he);
> +
> + tot_hit_left = TOT_LD_HIT(&c2c_left->stats);
> + tot_hit_right = TOT_LD_HIT(&c2c_right->stats);
> +
> + return tot_hit_left - tot_hit_right;
> +}
> +
> #define STAT_FN_ENTRY(__f) \
> static int \
> __f ## _entry(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp, \
> @@ -860,6 +901,58 @@ percent_hitm_cmp(struct perf_hpp_fmt *fmt __maybe_unused,
> return per_left - per_right;
> }
>
> +static double percent_tot_ld_hit(struct c2c_hist_entry *c2c_he)
> +{
> + struct c2c_hists *hists;
> + int tot = 0, st = 0;
> +
> + hists = container_of(c2c_he->he.hists, struct c2c_hists, hists);
> +
> + st = TOT_LD_HIT(&c2c_he->stats);
> + tot = TOT_LD_HIT(&hists->stats);
> +
> + return tot ? (double) st * 100 / tot : 0;
> +}
> +
> +static int
> +percent_tot_ld_hit_entry(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
> + struct hist_entry *he)
> +{
> + struct c2c_hist_entry *c2c_he;
> + int width = c2c_width(fmt, hpp, he->hists);
> + char buf[10];
> + double per;
> +
> + c2c_he = container_of(he, struct c2c_hist_entry, he);
> + per = percent_tot_ld_hit(c2c_he);
> + return scnprintf(hpp->buf, hpp->size, "%*s", width, PERC_STR(buf, per));
> +}
> +
> +static int
> +percent_tot_ld_hit_color(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
> + struct hist_entry *he)
> +{
> + return percent_color(fmt, hpp, he, percent_tot_ld_hit);
> +}
> +
> +static int64_t
> +percent_tot_ld_hit_cmp(struct perf_hpp_fmt *fmt __maybe_unused,
> + struct hist_entry *left, struct hist_entry *right)
> +{
> + struct c2c_hist_entry *c2c_left;
> + struct c2c_hist_entry *c2c_right;
> + double per_left;
> + double per_right;
> +
> + c2c_left = container_of(left, struct c2c_hist_entry, he);
> + c2c_right = container_of(right, struct c2c_hist_entry, he);
> +
> + per_left = percent_tot_ld_hit(c2c_left);
> + per_right = percent_tot_ld_hit(c2c_right);
> +
> + return per_left - per_right;
> +}
> +
> static struct c2c_stats *he_stats(struct hist_entry *he)
> {
> struct c2c_hist_entry *c2c_he;
> @@ -1412,6 +1505,14 @@ static struct c2c_dimension dim_ld_rmthit = {
> .width = 8,
> };
>
> +static struct c2c_dimension dim_tot_ld_hit = {
> + .header = HEADER_BOTH("Load Hit", "Total"),
> + .name = "tot_ld_hit",
> + .cmp = tot_ld_hit_cmp,
> + .entry = tot_ld_hit_entry,
> + .width = 8,
> +};
> +
> static struct c2c_dimension dim_tot_recs = {
> .header = HEADER_BOTH("Total", "records"),
> .name = "tot_recs",
> @@ -1460,6 +1561,15 @@ static struct c2c_dimension dim_percent_lcl_hitm = {
> .width = 7,
> };
>
> +static struct c2c_dimension dim_percent_tot_ld_hit = {
> + .header = HEADER_BOTH("Load Hit", "Pct"),
> + .name = "percent_tot_ld_hit",
> + .cmp = percent_tot_ld_hit_cmp,
> + .entry = percent_tot_ld_hit_entry,
> + .color = percent_tot_ld_hit_color,
> + .width = 8,
> +};
> +
> static struct c2c_dimension dim_percent_stores_l1hit = {
> .header = HEADER_SPAN("-- Store Refs --", "L1 Hit", 1),
> .name = "percent_stores_l1hit",
> @@ -1615,11 +1725,13 @@ static struct c2c_dimension *dimensions[] = {
> &dim_ld_l2hit,
> &dim_ld_llchit,
> &dim_ld_rmthit,
> + &dim_tot_ld_hit,
> &dim_tot_recs,
> &dim_tot_loads,
> &dim_percent_hitm,
> &dim_percent_rmt_hitm,
> &dim_percent_lcl_hitm,
> + &dim_percent_tot_ld_hit,
> &dim_percent_stores_l1hit,
> &dim_percent_stores_l1miss,
> &dim_dram_lcl,
> --
> 2.17.1
>
Powered by blists - more mailing lists