From: sashiko-bot@kernel.org
To: "Ian Rogers" <irogers@google.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 3/3] perf hist: Do not delete cumulative caller entries before stat_acc decays
Date: Mon, 26 Oct 2026 09:41:35 +0000 [thread overview]
Message-ID: <sashiko-outbox-184826@kernel.org> (raw)
In-Reply-To: <efe1d231090ef4dc43fe1f002a12c7c65c8ceda2.1792995775.git.irogers@google.com>
> When symbol_conf.cumulate_callchain is enabled (the default in
> 'perf top -g'), callchain parent/caller entries have he->stat.period == 0
> and accumulate their period in he->stat_acc->period.
>
> hists__decay_entry() decays both he->stat.period and he->stat_acc->period,
> but only checks if he->stat.period == 0 as the return condition for
> deleting the entry in hists__decay_entries(). As a result, every callchain
> caller entry with 0 self-period is unconditionally deleted from the
> histogram on the first decay pass, destroying its callchain tree while it
> still has non-zero cumulative period.
>
> Only mark an entry for deletion in hists__decay_entry() when both
> he->stat.period == 0 and (when cumulate_callchain is active)
> he->stat_acc->period == 0.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1792995775.git.irogers@google.com?part=3
next prev parent reply other threads:[~2026-10-26 9:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-26 6:50 [PATCH 0/3] perf: Fix libdw addr2line fallback, pr_debugN overhead, and cumulative hist decay Ian Rogers
2026-10-26 6:50 ` [PATCH 1/3] perf libdw: Optimize fallback logic for missing DWARF Ian Rogers
2026-10-26 9:31 ` sashiko-bot
2026-10-26 6:50 ` [PATCH 2/3] perf debug: Avoid calling eprintf() in pr_debugN() when verbose < n Ian Rogers
2026-10-26 9:35 ` sashiko-bot
2026-10-26 6:50 ` [PATCH 3/3] perf hist: Do not delete cumulative caller entries before stat_acc decays Ian Rogers
2026-10-26 9:41 ` sashiko-bot [this message]
2026-10-27 20:42 ` [PATCH 0/3] perf: Fix libdw addr2line fallback, pr_debugN overhead, and cumulative hist decay Arnaldo Carvalho de Melo
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