linux-kernel - Re: [Patch v3 3/7] perf/x86: Check if cpuc->events[*] pointer exists before accessing it

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Message-ID: <aKVgyV4XWfJGR6uK@tassilo>
Date: Tue, 19 Aug 2025 22:44:41 -0700
From: Andi Kleen <ak@...ux.intel.com>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>,
	kernel test robot <oliver.sang@...el.com>
Subject: Re: [Patch v3 3/7] perf/x86: Check if cpuc->events[*] pointer exists
 before accessing it

> Andi, I didn't fully get the exact meaning about the "log" here. When
> throttle is triggered, perf_event_throttle() has already called
> perf_log_throttle() to log the throttle event although only for the group
> leader. Is it enough?

Throttle normally doesn't involve data loss, just less samples. But this
is data loss, so it's an overflow.

-Andi