From: sashiko-bot@kernel.org
To: "Leo Yan" <leo.yan@arm.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH 1/4] perf synthetic-events: Split oversized thread maps into records
Date: Sun, 15 Nov 2026 13:46:52 +0000 [thread overview]
Message-ID: <sashiko-outbox-215545@kernel.org> (raw)
In-Reply-To: <20261115-perf_fix_large_threads-v1-1-69c9b86b9ae5@arm.com>
> PERF_RECORD_THREAD_MAP has a 16-bit header.size field. With 16 bytes of
> fixed fields and 24 bytes per entry, a record can hold at most 2,729
> threads within the 65,535-byte size limit.
>
> For larger maps, header.size overflows and no longer describes the
> entries counted by nr, so readers reject the record.
>
> Split larger maps into records that fit the size field. Set
> PERF_RECORD_MISC_THREAD_MAP_MORE in header.misc when another record
> follows, and clear it in the final record. Preserve entry order and the
> existing encoding for maps that fit in one record, including empty maps.
>
> Stop synthesis if allocation or the event callback fails.
>
> Signed-off-by: Leo Yan <leo.yan@arm.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261115-perf_fix_large_threads-v1-0-69c9b86b9ae5@arm.com?part=1
next prev parent reply other threads:[~2026-11-15 13:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-15 13:34 [PATCH 0/4] perf: Support thread maps larger than one record Leo Yan
2026-11-15 13:34 ` [PATCH 1/4] perf synthetic-events: Split oversized thread maps into records Leo Yan
2026-11-15 13:46 ` sashiko-bot [this message]
2026-11-15 13:34 ` [PATCH 2/4] perf: Assemble split thread maps in script and stat report Leo Yan
2026-11-15 13:56 ` sashiko-bot
2026-11-15 13:34 ` [PATCH 3/4] perf test: Cover multi-record thread map synthesis Leo Yan
2026-11-15 13:40 ` sashiko-bot
2026-11-15 13:34 ` [PATCH 4/4] perf docs: Describe multi-record thread maps Leo Yan
2026-11-15 13:41 ` sashiko-bot
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