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 CC53E1A23A0; Wed, 12 Nov 2025 01:08:15 +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=1762909698; cv=none; b=j1us9Xt+AjU0nByZqRENNr9g3MCpfMXD4zjmG+xFq3l6TGBPCRltas1dA8aFRR0dPMcsPhtURbEB9nqylCksa4S2uB8DXBtQ4FcQ9frfaKkeZUpARuNzDHb4E3QGMuexFyMq0t6fdleKXKAuRPqKQp8iyl37GtHkyUmKf/MotTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762909698; c=relaxed/simple; bh=8bjLCvsDDMG1Xk+9mxuiLdUVVLRsD6kVlBsmX6XuoiU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AUwpJXr5zvXi48oz4tEILvPVxRgRFXU+q1uguHmsxDUKLZkyr3YevcCDID5GseVtsxlYvW0Zqa1y9wbRAkBmKHcvqT3BO2gXiFXSCGO5kM5bOnyujgtDddAsQLeWsynBsSWa9OgTb49HeyEIy3J3ybyNmuxKT928c9+eghMS768= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZgUDxWR4; 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="ZgUDxWR4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2ECF7C116B1; Wed, 12 Nov 2025 01:08:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762909695; bh=8bjLCvsDDMG1Xk+9mxuiLdUVVLRsD6kVlBsmX6XuoiU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZgUDxWR4Rrs0Se3DGWjVsMcwuWsuZ/E+4tyKcWf7BZ1LYPgEI9uzu2xoLgQUkgzIm 1h/3nL27179pfezeNMb4REj+dcVXW2kcidrvN0fW5C+dSqGhrkFWiLx1XHLbQOtAe8 tKhKiKGu92sysCDMRcQT9Qo8nhFQHr7C1hQF6QqZj1ydbVr7G13xmCV3tyzWJPMUmj yoIKHp4LoEXidxpC+68rstr2w8DxcetS3xS1BfhCOHXWvmTfOKbdw9ivLVqf1+64g8 TYewQm6zP74koTNmZmST+qW7JTYztzKZ7+vdExQ+sYk4PuLq7+y8bXz7qpGTbf9bnZ BIzhPv/zQRujg== Date: Tue, 11 Nov 2025 17:08:11 -0800 From: Namhyung Kim To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Adrian Hunter , James Clark , Xu Yang , Chun-Tse Shao , Thomas Richter , Sumanth Korikkar , Collin Funk , Thomas Falcon , Howard Chu , Dapeng Mi , Levi Yun , Yang Li , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Andi Kleen , Weilin Wang Subject: Re: [PATCH v4 00/18] Message-ID: References: <20251111212206.631711-1-irogers@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 Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Nov 11, 2025 at 03:13:35PM -0800, Ian Rogers wrote: > On Tue, Nov 11, 2025 at 2:42 PM Namhyung Kim wrote: > > > > On Tue, Nov 11, 2025 at 01:21:48PM -0800, Ian Rogers wrote: > > > Prior to this series stat-shadow would produce hard coded metrics if > > > certain events appeared in the evlist. This series produces equivalent > > > json metrics and cleans up the consequences in tests and display > > > output. A before and after of the default display output on a > > > tigerlake is: > > > > > > Before: > > > ``` > > > $ perf stat -a sleep 1 > > > > > > Performance counter stats for 'system wide': > > > > > > 16,041,816,418 cpu-clock # 15.995 CPUs utilized > > > 5,749 context-switches # 358.376 /sec > > > 121 cpu-migrations # 7.543 /sec > > > 1,806 page-faults # 112.581 /sec > > > 825,965,204 instructions # 0.70 insn per cycle > > > 1,180,799,101 cycles # 0.074 GHz > > > 168,945,109 branches # 10.532 M/sec > > > 4,629,567 branch-misses # 2.74% of all branches > > > # 30.2 % tma_backend_bound > > > # 7.8 % tma_bad_speculation > > > # 47.1 % tma_frontend_bound > > > # 14.9 % tma_retiring > > > ``` > > > > > > After: > > > ``` > > > $ perf stat -a sleep 1 > > > > > > Performance counter stats for 'system wide': > > > > > > 2,890 context-switches # 179.9 cs/sec cs_per_second > > > 16,061,923,339 cpu-clock # 16.0 CPUs CPUs_utilized > > > 43 cpu-migrations # 2.7 migrations/sec migrations_per_second > > > 5,645 page-faults # 351.5 faults/sec page_faults_per_second > > > 5,708,413 branch-misses # 1.4 % branch_miss_rate (88.83%) > > > 429,978,120 branches # 26.8 M/sec branch_frequency (88.85%) > > > 1,626,915,897 cpu-cycles # 0.1 GHz cycles_frequency (88.84%) > > > 2,556,805,534 instructions # 1.5 instructions insn_per_cycle (88.86%) > > > TopdownL1 # 20.1 % tma_backend_bound > > > # 40.5 % tma_bad_speculation (88.90%) > > > # 17.2 % tma_frontend_bound (78.05%) > > > # 22.2 % tma_retiring (88.89%) > > > > > > 1.002994394 seconds time elapsed > > > ``` > > > > > > Having the metrics in json brings greater uniformity, allows events to > > > be shared by metrics, and it also allows descriptions like: > > > ``` > > > $ perf list cs_per_second > > > ... > > > cs_per_second > > > [Context switches per CPU second] > > > ``` > > > > > > A thorn in the side of doing this work was that the hard coded metrics > > > were used by perf script with '-F metric'. This functionality didn't > > > work for me (I was testing `perf record -e instructions,cycles` > > > with/without leader sampling and then `perf script -F metric` but saw > > > nothing but empty lines) but anyway I decided to fix it to the best of > > > my ability in this series. So the script side counters were removed > > > and the regular ones associated with the evsel used. The json metrics > > > were all searched looking for ones that have a subset of events > > > matching those in the perf script session, and all metrics are > > > printed. This is kind of weird as the counters are being set by the > > > period of samples, but I carried the behavior forward. I suspect there > > > needs to be follow up work to make this better, but what is in the > > > series is superior to what is currently in the tree. Follow up work > > > could include finding metrics for the machine in the perf.data rather > > > than using the host, allowing multiple metrics even if the metric ids > > > of the events differ, fixing pre-existing `perf stat record/report` > > > issues, etc. > > > > > > There is a lot of stat tests that, for example, assume '-e > > > instructions,cycles' will produce an IPC metric. These things needed > > > tidying as now the metric must be explicitly asked for and when doing > > > this ones using software events were preferred to increase > > > compatibility. As the test updates were numerous they are distinct to > > > the patches updating the functionality causing periods in the series > > > where not all tests are passing. If this is undesirable the test fixes > > > can be squashed into the functionality updates, but this will be kind > > > of messy, especially as at some points in the series both the old > > > metrics and the new metrics will be displayed. > > > > > > v4: K/sec to M/sec on branch frequency (Namhyung), perf script -F > > > metric to-done a system-wide calculation (Namhyung) and don't > > > crash because of the CPU map index couldn't be found. Regenerate > > > commit messages but the cpu-clock was always yielding 0 on my > > > machine leading to a lot of nan metric values. > > > > This is strange. The cpu-clock should not be 0 as long as you ran it. > > Do you think it's related to the scale unit change? I tested v3 and > > didn't see the problem. > > It looked like a kernel issue. The raw counts were 0 before being > scaled. All metrics always work on unscaled values. It is only the > commit messages and the formatting is more important than the numeric > values - which were correct for a cpu-clock of 0. Hmm.. ok. I don't see the problem when I test the series so it may be a problem in your environment. Thanks, Namhyung