From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00CBA1C8637; Mon, 17 Mar 2025 16:46:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742230003; cv=none; b=H4hwQHRkR+GPuYv3LG4VwueQqEi3KqGqWO7XQbpAFvy0bMQAnyZdex6+O/OtEW3wqE8dNMvHarMB4TxBrcy6GNrzMOt6yLdBpo8ttPel9mlZa0uEEESmL3xpDu18VLM0oHHYZ0ptl7V4YikP9i+gMfabtuG6xbO3hnC3n72FKxM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742230003; c=relaxed/simple; bh=+gpgx1f/Gxc036wNUlCVYAX4Xs//acADzBzuOoLrCmI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XrDWI1JAV+ViKKW+MYnxulhxaSuRP7OXL+veLTcK3Ed0LROq848D0Q4cokj0zYvrx9+LD1LQx/hn/6YX+fslc4p3g8kLtelWzyH1zkdAKHa4iwX6hpttfc3N8+3xzGCxH91lO0C4POvapBmTwOZ2jCkbR63lo7uLAS3jIGAZr1k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lSyJzNu1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lSyJzNu1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB9D1C4CEE3; Mon, 17 Mar 2025 16:46:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742230002; bh=+gpgx1f/Gxc036wNUlCVYAX4Xs//acADzBzuOoLrCmI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lSyJzNu1XI24vzUJST7LRc1wPpIUK8XSunvC5pBTzK2p5A0BCsBPOlhHmLIugLhc1 hYUD6cYUW4tCNSVi0feAcVrxk3oPVFcvf435Zmn0WabvlwIQKNdQzpULX1re49daXH CIYEP8106uxqZHyfkuGEh19aH+6wBph+fomwnc7eR+Dz5Hek0pqkCAua1CjrZ6j9Bu ezxDtFDcVWzhrk3SPzqFE/Fjy/XWo19PzHMHoYnNtDCMw/JhrBWHOV2Tw3Ldmohkw/ xMb57F7AEUzAZAsDfqa5oMRslK4Kt3EnBaUOx+LMtbgDOhqxrllkRQwAARN76f2KJk n0t3MYcYMjhRw== Date: Mon, 17 Mar 2025 09:46:40 -0700 From: Namhyung Kim To: Arnaldo Carvalho de Melo Cc: Chun-Tse Shao , linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, terrelln@fb.com, leo.yan@arm.com, james.clark@linaro.org, christophe.leroy@csgroup.eu, ben.gainey@arm.com, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v2 1/2] perf record: Add 8-byte aligned event type PERF_RECORD_COMPRESSED2 Message-ID: References: <20250303183646.327510-1-ctshao@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Mar 17, 2025 at 01:17:46PM -0300, Arnaldo Carvalho de Melo wrote: > On Mon, Mar 17, 2025 at 12:52:09PM -0300, Arnaldo Carvalho de Melo wrote: > > On Fri, Mar 14, 2025 at 06:27:05PM -0700, Namhyung Kim wrote: > > > On Mon, Mar 03, 2025 at 10:32:40AM -0800, Chun-Tse Shao wrote: > > > > The original PERF_RECORD_COMPRESS is not 8-byte aligned, which can cause > > > > asan runtime error: > > > > > # Build with asan > > > > $ make -C tools/perf O=/tmp/perf DEBUG=1 EXTRA_CFLAGS="-O0 -g -fno-omit-frame-pointer -fsanitize=undefined" > > > > # Test success with many asan runtime errors: > > > > $ /tmp/perf/perf test "Zstd perf.data compression/decompression" -vv > > > > 83: Zstd perf.data compression/decompression: > > > > ... > > > > util/session.c:1959:13: runtime error: member access within misaligned address 0x7f69e3f99653 for type 'union perf_event', which requires 13 byte alignment > > > > 0x7f69e3f99653: note: pointer points here > > > > d0 3a 50 69 44 00 00 00 00 00 08 00 bb 07 00 00 00 00 00 00 44 00 00 00 00 00 00 00 ff 07 00 00 > > > > ^ > > > > util/session.c:2163:22: runtime error: member access within misaligned address 0x7f69e3f99653 for type 'union perf_event', which requires 8 byte alignment > > > > 0x7f69e3f99653: note: pointer points here > > > > d0 3a 50 69 44 00 00 00 00 00 08 00 bb 07 00 00 00 00 00 00 44 00 00 00 00 00 00 00 ff 07 00 00 > > > > ^ > > > > ... > > > > > Since there is no way to align compressed data in zstd compression, this > > > > patch add a new event type `PERF_RECORD_COMPRESSED2`, which adds a field > > > > `data_size` to specify the actual compressed data size. The > > > > `header.size` contains the total record size, including the padding at > > > > the end to make it 8-byte aligned. > > > > > Tested with `Zstd perf.data compression/decompression` > > > > Looks good to me. > > > > Arnaldo, are you ok with adding a new record type for this? > > > Checking the discussion and the patch. > > My first impression yesterday when I saw this on the smartphone was: how > will an old perf binary handle the new PERF_RECORD_COMPRESSED2? Will it > ignore it while emitting a warning, since it can be skipped and then > what we will get a partial view? > > Having some session output showing how an older perf binary handles > PERF_RECORD_COMPRESS2 would be informative. I think it'll show the below warning: []: failed to process type: 83 Thanks, Namhyung