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 A4F8D188907; Mon, 17 Mar 2025 16:17:49 +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=1742228269; cv=none; b=ppmD6I+6IJF2EEGIrTC0zLsb7onL+hnft5MbCx0cT6+q75elmLYbfkJgb3SFZ3smCDNYylG6Htkiuev5pkUsyZ4ed3JzgvL2bdA5uG6Ya3l18DELjy76x9ItMZBgA7Ou/iy/5X9ptB6mtlYLDuzafdnTz/tnsb4sSa3DvvT4kWU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742228269; c=relaxed/simple; bh=G42GrbRlFLadgeAorXitKrnMtX3TCyZknmA2IK3Bfk0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GTYMC5D2riKawAkKLIWEF+pbOYLdXsaQlFDCkAsS3OjbzOQnuFzfxMoxF5UbB2zscWTb3NwZs8jGEtKdFJK+YAUJoR/2Th+9JYcZ5OOCHW3DvnBs9WSz7TruekYuRdwUCUaa0bO2Xvv2gT99Sd/crwH9kBJrDchl0kn0TBvi1iA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D4XUfczs; 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="D4XUfczs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9201C4CEE3; Mon, 17 Mar 2025 16:17:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742228269; bh=G42GrbRlFLadgeAorXitKrnMtX3TCyZknmA2IK3Bfk0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D4XUfczseN+rrOTPQuSZejroQ55t7/R8yhHyg2TG2Tupr5raFLs5Wzetyo88H+cyn Dq3z3oW7xQB7+OZoqOyuPhfwt6PZ9OC4OT77sk9KsRuhlnGVgWScxSaxsbtSYzf4F+ VXUlCcMu7o5qRPXsqX8PFkhi4gdX0gKPDkkDM+wohSpn3zAxpbaBmQ9b3gvoBEjAwh EEovcEMfbONYlKjgZy1hlYLEXmAJlbB+thdvhVnpctjxxgLvMzIR1FO10XSUR8ccLE ZWwpYFC8jLivmP8F6WyPft+wBbqhOEE+gIB39MhcTbjzS3THdb25FrAiTKCAnWBA/5 TaQa5kdB86ieg== Date: Mon, 17 Mar 2025 13:17:46 -0300 From: Arnaldo Carvalho de Melo To: Namhyung Kim 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=us-ascii Content-Disposition: inline In-Reply-To: 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'll try to reproduce/test this all... - Arnaldo