From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ian Rogers <irogers@google.com>,
Kan Liang <kan.liang@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-perf-users@vger.kernel.org, bpf@vger.kernel.org,
Kevin Nomura <nomurak@google.com>, Song Liu <song@kernel.org>
Subject: Re: [PATCH] perf report: Do not process non-JIT BPF ksymbol events
Date: Fri, 07 Mar 2025 10:09:58 -0800 [thread overview]
Message-ID: <174137099810.213280.18383915542896888005.b4-ty@kernel.org> (raw)
In-Reply-To: <20250305232838.128692-1-namhyung@kernel.org>
On Wed, 05 Mar 2025 15:28:38 -0800, Namhyung Kim wrote:
> The length of PERF_RECORD_KSYMBOL for BPF is a size of JITed code so
> it'd be 0 when it's not JITed. The ksymbol is needed to symbolize the
> code when it gets samples in the region but non-JITed code cannot get
> samples. Thus it'd be ok to ignore them.
>
> Actually it caused a performance issue in the perf tools on old ARM
> kernels where it can refuse to JIT some BPF codes. It ended up
> splitting the existing kernel map (kallsyms). And later lookup for a
> kernel symbol would create a new kernel map from kallsyms and then
> split it again and again. :(
>
> [...]
Applied to perf-tools-next, thanks!
Best regards,
Namhyung
prev parent reply other threads:[~2025-03-07 18:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-05 23:28 [PATCH] perf report: Do not process non-JIT BPF ksymbol events Namhyung Kim
2025-03-06 4:09 ` Song Liu
2025-03-06 6:25 ` Adrian Hunter
2025-03-06 6:45 ` Namhyung Kim
2025-03-06 6:48 ` Adrian Hunter
2025-03-06 7:50 ` Namhyung Kim
2025-03-07 18:09 ` Namhyung Kim [this message]
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