From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793819454; b=SYkvfHY2h7s7IybXbuFTt8Tr2pDPe2yn3GCRt2VSImUjBUbDL6otgFQouN2MoxDwr0DJ eoo9bkjh7s+yUpyDgeRpQUISNfYsPhKfstygwMwS8DzoSlfrdV38WpJIYhYzY9wAwa1Oc IHAit7xq5uq5KQaV9FPixduX0sipQaxu6Q9zHlXAWJPTWSnph7bSploZza8MMntv+BF3l goELdy8aThrKgnPoMFeNk4pa/GuAqNZmBYM5x+pjhQPiCFMHlzjz1Tq+fAjV7c2IE2DOO s7EhQZIhTifu4JW3JHKlGzgJxSSuCprqya8QE4HzXrugLra0T0xXIqdKYeFFU+9wkVQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793819454; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=quXPJLGKIchgKPiIO3f8isxxl665gX28P2sTOConoZk=; b=mWFJ+XIfhRZ2skSz74oF+tsHdDcpKwkj3D7iWjLC9I4U7UsRgRumbIeqb6wJmszxFKM3 tHgfNsKTfCVuguFuhnLGxUB5FAYRcQiP8GK3qzCZG/YC61H9/N7aYlpQdIRzOAOB9/Rk1 jtWYs0V2ysF04YVjjZvJGQGykd021mWlWHIFHunwtlsNFYb+5l8IQi3S7wcmqd8lS6yY3 jBXNy0EmQlAeBpOAqtkC3SDGAghWiwR0iXCf0Q0PQQcsrllkfJNzobwXzg7h7Rj5CxVrc nNLojNUkhEDYljK71mhgMX9i9d18+x0PgVSAKgjpPZo4nmO5a8nXTr5NHbjE5jcfvMw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ZoBKGu4l; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7355C606A329 for ; Wed, 4 Nov 2026 19:10:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ZoBKGu4l Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B4981F0093A; Wed, 4 Nov 2026 19:10:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793819454; bh=quXPJLGKIchgKPiIO3f8isxxl665gX28P2sTOConoZk=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=ZoBKGu4lsUqRszr8kHtlaJ5kBTB64LklPrV8pe0sOZ+xmT1Ga/tdWX/OY1fkzbVNf KjH2OkJ4OoEtAy05CUq1TSKsDCY5MpCgAAxjJNAUP6SeI6hGtdiCVbE8FhDsHdPHRD 4XuRpmCVudqkH81KWV4qIepNGStx9JNHwheQud0kGmeQxEqhlrvGhuQ/Ze1PnmsLRJ dbk22CRgmLaLAVIztY39J2EuckUy0S9tJEvECosVdqDItYtmFs9s6BjQBj8oRABGcv IzoId235kRsKs44dA1S0FyVGLJr58mi1AesyHEFPClQPLJKJUYmhB2HCS+znlLHO0Q u8Irado1qnIAQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v6 12/13] alpha/perf: sample only retired instructions for precise events Reply-To: sashiko-reviews@lists.linux.dev To: "Matt Turner" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261104-alpha-profileme-v6-12-63362e9290a3@gmail.com> References: <20261104-alpha-profileme-v6-0-63362e9290a3@gmail.com> <20261104-alpha-profileme-v6-12-63362e9290a3@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Nov 2026 19:10:53 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > ProfileMe samples include instructions killed on a wrong path, which > show up as hot spots in perf report although they did no work. On an > EV7 loop with a randomly mispredicted branch, 19% of the samples were > killed before being mapped and another 48% later. >=20 > PEBS and AMD IBS op samples are of retired instructions only, so make > precise_ip imply the retired filter, unless filters are given. The > profileme bit still selects every sample. With cycles:p, both kinds of > killed sample went to 0%. >=20 > DTB miss samples, whose instruction is aborted, are then dropped too: > cycles:p reports DTB hits only, and the misses need cpu/cycles,trapped/p. >=20 > The kept samples carry the full period, as do those AMD IBS keeps when > its swfilt discards others. So in frequency mode the sample rate, and > the event count perf report estimates from the periods, fall by the > share of killed instructions: to about a third on that loop. >=20 > Suggested-by: Ian Rogers > Assisted-by: Claude:claude-opus-5-5 > Signed-off-by: Matt Turner Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261104-alpha-prof= ileme-v6-0-63362e9290a3@gmail.com?part=3D12