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[66.183.142.209]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-225c6bd5db8sm98745ad.257.2025.03.12.14.38.49 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Mar 2025 14:38:50 -0700 (PDT) From: "Doug Smythies" To: "'Artem Bityutskiy'" , "'Rafael J. Wysocki'" Cc: "'LKML'" , "'Daniel Lezcano'" , "'Christian Loehle'" , "'Aboorva Devarajan'" , "'Linux PM'" , "Doug Smythies" References: <1916668.tdWV9SEqCh@rjwysocki.net> <4917ca35e5e0c7035f09c02d5080a69ed3e88c44.camel@linux.intel.com> In-Reply-To: <4917ca35e5e0c7035f09c02d5080a69ed3e88c44.camel@linux.intel.com> Subject: RE: [RFT][PATCH v1 0/5] cpuidle: menu: Avoid discarding useful information when processing recent idle intervals Date: Wed, 12 Mar 2025 14:38:52 -0700 Message-ID: <005801db9397$266ddac0$73499040$@telus.net> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Content-Language: en-ca Thread-Index: AQD+BgZZG1yDo2pCGl+Ay1eM9EzyOwIPMwSptRqYRhA= On 2025.02.07 06:49 Artem Bityutskiy wrote: > Hi, > > thanks for the patches! > > On Thu, 2025-02-06 at 15:21 +0100, Rafael J. Wysocki wrote: >> Hi Everyone, >> >> This work had been triggered by a report that commit 0611a640e60a ("eventpoll: >> prefer kfree_rcu() in __ep_remove()") had caused the critical-jOPS metric of >> the SPECjbb 2015 benchmark [1] to drop by around 50% even though it generally >> reduced kernel overhead. Indeed, it was found during further investigation >> that the total interrupt rate while running the SPECjbb workload had fallen as >> a result of that commit by 55% and the local timer interrupt rate had fallen >> by almost 80%. > > I ran SPECjbb2015 with and it doubles critical-jOPS and basically makes it > "normal" again. Thanks! > > Reported-by: Artem Bityutskiy > Tested-by: Artem Bityutskiy None of the tests I run/ran show anywhere near that magnitude of change, and because it is not a free test, I thought I would try to create one. For my "critical-jobs" test I searched for differences over a wide range of jobs per second and workload per job. I found one significant difference, but the opposite of Artem's SPECjbb results: load seconds total jobs jps min 50th 90th 95th 99th max menu-614 1 60 1174500 19575 160 470 620 650 800 1620 menu-614-p 1 60 1175251 19588 160 530 690 720 860 1600 0.1% 0.0% 12.8% 11.3% 10.8% 7.5% -1.2% menu-614 2 60 1102431 18374 250 600 750 790 930 2600 menu-614-p 2 60 1111070 18518 260 560 690 730 860 1360 0.8% 4.0% -6.7% -8.0% -7.6% -7.5% -47.7% menu-614 3 60 987408 16457 340 920 1040 1090 1210 7100 menu-614-p 3 60 1000063 16668 340 750 850 890 980 2390 1.3% 0.0% -18.5% -18.3% -18.3% -19.0% -66.3% menu-614 4 60 914690 15245 410 1510 1830 1860 1980 3630 menu-614-p 4 60 927129 15452 440 11790 14920 15160 15400 95720 1.4% 7.3% 680.8% 715.3% 715.1% 677.8% 2536.9% menu-614 5 60 885468 14758 540 9680 11400 11800 15460 74040 menu-614-p 5 60 895095 14918 570 25430 30150 30640 31250 137830 1.1% 5.6% 162.7% 164.5% 159.7% 102.1% 86.2% menu-614 6 60 840939 14016 630 45660 52070 57750 84340 189980 menu-614-p 6 60 843512 14059 620 44750 52220 58750 85930 199990 0.3% -1.6% -2.0% 0.3% 1.7% 1.9% 5.3% menu-614 7 60 797438 13291 740 61420 68130 71040 101060 199990 menu-614-p 7 60 796645 13277 670 55630 63790 68140 98920 199990 -0.1% -9.5% -9.4% -6.4% -4.1% -2.1% 0.0% Notes: menu-614 = kernel 6.14-RC1 menu-614-p = kernel 6.14RC1 + this patch set I am still on RC1 because of earlier testing, reported a few weeks ago. load is arbitrary, but 2 does twice as much work as 1 and so on. (for most of this work the load has been between 10 and 1000.) Jps = jobs per second and is queuing task limited for these particular test runs. min, percentiles, and max columns are in units of microseconds of job execution time. For the percent calculations, negative is better. The data is clamped at 199,990 uSeconds, so we don't actually know what 3 of the max's were, not that we really care. It is more the 95th percentile area we care about. I am not suggesting that overall the patch set isn't a net positive. Just that I found conditions where the results are poor. So, what's the point of this email? With respect to the other thread "TEO as default governor ?" [1] That is such a difficult question, as there are often conflicting results. But overall, for my testing they are very similar these days. [1] https://lore.kernel.org/linux-pm/d6de2118-eae1-4abb-818b-b3420732c82a@arm.com/T/#t