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Tue, 8 Jul 2025 17:29:09 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5F5AA20043; Tue, 8 Jul 2025 17:29:09 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1617A20040; Tue, 8 Jul 2025 17:29:07 +0000 (GMT) Received: from [9.124.215.76] (unknown [9.124.215.76]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 8 Jul 2025 17:29:06 +0000 (GMT) Message-ID: <931f8673-a2b0-4b4e-8ae8-269b5a5c235d@linux.ibm.com> Date: Tue, 8 Jul 2025 22:59:06 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/12] sched: Address schbench regression To: Chris Mason , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com References: <20250702114924.091581796@infradead.org> <132949bc-f901-40e6-a34c-d1d67d03d8b6@linux.ibm.com> <21eb2e07-7ac9-42ef-a8f7-15a01a3c1629@meta.com> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: <21eb2e07-7ac9-42ef-a8f7-15a01a3c1629@meta.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzA4MDE0NiBTYWx0ZWRfXzzU9F2g7gLFJ COMHRJ6Ov+mJGFxG5DtnsIVJ1wUOTkHlJWzM0L8apynAJTq9pciO/YAoLPQkpuwo/ywTUVDDWWF tJ6Jj1ITxR2ietJap65aQXYRl1eEXJnzfjzQj0YRsOm7qXPyXaK4KHfGpDyynTQZNTHpnfeKckv zdyXWymXO3WbABXKpg1F8jqSU+EkMLQpUecjNS9Qr6TjdOAJXXZ5cDbOwL9XZHX5L+M/zVBcpjy 6XnR8R27fklahf/dOnQN3Mnlaig75hnaGGXi/tJLwAUiAeEbz+n3SisTzj/+pNkY0QjYy4FbwI9 3F3mmNKSA2LxeUSaVLchkDR+LNeYYZWZ9VZBa956PoLJ1HRiWTL1qbqCgeEYakBBVzzMFfCzZ48 qEfgs71RNnx2mSNo/qz8GgfLu0OplchQpvbaLcbI+18cOMkvMVYUo8QCI/0YHPGYI0rfgodz X-Authority-Analysis: v=2.4 cv=XYeJzJ55 c=1 sm=1 tr=0 ts=686d5569 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=Wb1JkmetP80A:10 a=VwQbUJbxAAAA:8 a=JfrnYn6hAAAA:8 a=FOH2dFAWAAAA:8 a=6cMEACPwkbmYPFGOAeUA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=1CNFftbPRP8L7MoqJWF3:22 X-Proofpoint-ORIG-GUID: gFOfqVCVdzaz6O7iC1l_z_mW2qrcjM_8 X-Proofpoint-GUID: nqbJKTt2w2pZwbrYou5eQEA5mz70HTjI X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-07-08_04,2025-07-07_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 suspectscore=0 mlxscore=0 impostorscore=0 phishscore=0 bulkscore=0 clxscore=1015 spamscore=0 mlxlogscore=460 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2507080146 On 7/8/25 20:39, Chris Mason wrote: > On 7/7/25 5:05 AM, Shrikanth Hegde wrote: >> >> >> On 7/2/25 17:19, Peter Zijlstra wrote: >>> Hi! >>> >>> Previous version: >>> >>>    https://lkml.kernel.org/r/20250520094538.086709102@infradead.org >>> >>> Changes: >>>   - keep dl_server_stop(), just remove the 'normal' usage of it (juril) >>>   - have the sched_delayed wake list IPIs do select_task_rq() (vingu) >>>   - fixed lockdep splat (dietmar) >>>   - added a few preperatory patches >>> >>> >>> Patches apply on top of tip/master (which includes the disabling of >>> private futex) >>> and clm's newidle balance patch (which I'm awaiting vingu's ack on). >>> >>> Performance is similar to the last version; as tested on my SPR on >>> v6.15 base: >>> >> >> >> Hi Peter, >> Gave this a spin on a machine with 5 cores (SMT8) PowerPC system. >> >> I see significant regression in schbench. let me know if i have to test >> different >> number of threads based on the system size. >> Will go through the series and will try a bisect meanwhile. > > Not questioning the git bisect results you had later in this thread, but > double checking that you had the newidle balance patch in place that > Peter mentioned? > > https://lore.kernel.org/lkml/20250626144017.1510594-2-clm@fb.com/ > > The newidle balance frequency changes the cost of everything else, so I > wanted to make sure we were measuring the same things. > Hi Chris. It was base + series only. and base was 8784fb5fa2e0("Merge irq/drivers into tip/master"). So it didn't have your changes. I tested again with your changes and i still see a major regression. ./schbench -L -m 4 -M auto -t 64 -n 0 -t 60 -i 60 Wakeup Latencies percentiles (usec) runtime 30 (s) (18848611 total samples) 50.0th: 115 (5721408 samples) 90.0th: 238 (7500535 samples) * 99.0th: 316 (1670597 samples) 99.9th: 360 (162283 samples) min=1, max=1487 RPS percentiles (requests) runtime 30 (s) (31 total samples) 20.0th: 623616 (7 samples) * 50.0th: 629760 (15 samples) 90.0th: 631808 (7 samples) min=617820, max=635475 average rps: 628514.30 git log --oneline 7aaf5ef0841b (HEAD) sched: Add ttwu_queue support for delayed tasks f77b53b6766a sched: Change ttwu_runnable() vs sched_delayed 986ced69ba7b sched: Use lock guard in sched_ttwu_pending() 2c0eb5c88134 sched: Clean up ttwu comments e1374ac7f74a sched: Re-arrange __ttwu_queue_wakelist() 7e673db9e90f psi: Split psi_ttwu_dequeue() e2225f1c24a9 sched: Introduce ttwu_do_migrate() 80765734f127 sched: Add ttwu_queue controls 745406820d30 sched: Use lock guard in ttwu_runnable() d320cebe6e28 sched: Optimize ttwu() / select_task_rq() 329fc7eaad76 sched/deadline: Less agressive dl_server handling 708281193493 sched/psi: Optimize psi_group_change() cpu_clock() usage c28590ad7b91 sched/fair: bump sd->max_newidle_lb_cost when newidle balance fails 8784fb5fa2e0 (origin/master, origin/HEAD) Merge irq/drivers into tip/master