From: sashiko-bot@kernel.org
To: "Mykyta Yatsenko" <mykyta.yatsenko5@gmail.com>
Cc: linux-perf-users@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 2/3] perf bpf_counter: Track valid BPF counter snapshots
Date: Tue, 08 Sep 2026 14:39:07 +0000 [thread overview]
Message-ID: <20260908143907.B139B1F00A3D@smtp.kernel.org> (raw)
In-Reply-To: <20260908-bpftool_cyles_per_run-v3-2-60e86f325c35@meta.com>
> From: Mykyta Yatsenko <yatsenko@meta.com>
>
> The perf profiler uses a zero counter value to reject an invalid entry
> snapshot. However, zero is valid when the PMU has not scheduled the event.
>
> To reproduce the issue, fill the PMU with other events and profile a
> long-running BPF program for iTLB misses. In this test, the entry read
> returned 0.
>
> Use an armed flag to track successful entry reads. Reset the flag before
> each new read. The fexit path clears the flag when it consumes the
> snapshot.
>
> Fixes: fa853c4b839e ("perf stat: Enable counting events for BPF programs")
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260908-bpftool_cyles_per_run-v3-0-60e86f325c35@meta.com?part=2
next prev parent reply other threads:[~2026-09-08 14:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-08 14:27 [PATCH bpf-next v3 0/3] bpftool: Improve perf counter reporting Mykyta Yatsenko
2026-09-08 14:27 ` [PATCH bpf-next v3 1/3] bpftool: Track perf counter snapshot state Mykyta Yatsenko
2026-09-08 14:35 ` sashiko-bot
2026-09-08 22:08 ` Quentin Monnet
2026-09-08 23:56 ` Andrii Nakryiko
2026-09-09 9:19 ` Mykyta Yatsenko
2026-09-11 23:57 ` Andrii Nakryiko
2026-09-08 14:27 ` [PATCH bpf-next v3 2/3] perf bpf_counter: Track valid BPF counter snapshots Mykyta Yatsenko
2026-09-08 14:39 ` sashiko-bot [this message]
2026-09-08 14:27 ` [PATCH bpf-next v3 3/3] bpftool: Scale counters and report cycles per run Mykyta Yatsenko
2026-09-08 14:42 ` sashiko-bot
2026-09-08 16:21 ` bot+bpf-ci
2026-09-08 17:37 ` Mykyta Yatsenko
2026-09-08 22:08 ` Quentin Monnet
2026-09-09 0:02 ` Andrii Nakryiko
2026-09-09 9:49 ` Mykyta Yatsenko
2026-09-12 0:01 ` Andrii Nakryiko
2026-09-08 18:01 ` [PATCH bpf-next v3 0/3] bpftool: Improve perf counter reporting Ihor Solodrai
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