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Tue, 18 Aug 2026 09:04:57 +0000 (GMT) Received: from li-4c4c4544-0039-5810-8039-c8c04f434234.ibm.com (unknown [9.111.9.19]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 18 Aug 2026 09:04:57 +0000 (GMT) Message-ID: Subject: Re: [PATCH v3 0/7] sched: Flatten the pick From: Szabina Korbai To: K Prateek Nayak , Peter Zijlstra , mingo@kernel.org Cc: longman@redhat.com, chenridong@huaweicloud.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, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, jstultz@google.com, qyousef@layalina.io, euan@linux.ibm.com, huschle@linux.ibm.com Date: Tue, 18 Aug 2026 10:04:57 +0100 In-Reply-To: References: <20260605105513.354837583@infradead.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE4MDA2NiBTYWx0ZWRfX5sspVmhCuK3Y zHSI38v8n2cnZjvfT6DOQhxPLgB3A/A/sclF+mPy9nXrXlY19LlbeMNgfJ4qT5lCGTUoHcb04o8 uYT8omkwavfdwMKo+ynOvKJm+FsMFHtQn2ADrKyD0UxQxnkfG/nPDNdhIJpJOAcpvQ4Uq/p61gw NvfdO0h+HDBktWC8kKvwMSTuzSJgJhNbjodLkPmoWZs7HPyXt7DAZ1AICdF+mcjt6y7KQl5CaLL b8AbFiLAZNfvkf4d9LBHpWx65X0d9hfNUnOHU9IURSVdLClzWUSAx8Eq5xqA7gJWFKHz5zfMdr7 5e+e1aIzlJahvpHGlh0s8MKVPBaWOLAgBz0xr1FE3ARwCLqdALJeLk7zy1VECdI2P0o6j1uGLa6 rXapIpuIro2GOF0/6Xp7ZXQYdbs7gm1LjZtK9lHtQYRV8YnBL1NxBkQu6d3ccy5OvAlfmBD8Ch2 GXnvToKsxw8Pw683KGg== X-Proofpoint-ORIG-GUID: HgC3zz5kuieepGgpfXIhXn_YazUdOdsv X-Proofpoint-Spam-Info: AW1haW4tMjYwODE4MDA2NiBTYWx0ZWRfX3by2WI2SKw+N Vk4wMBnzEtOzmC770ds0cWQX8c7+aPDA4sQw7BSSmQtq2QSyd/dFdOBO65kQISNw7QX+3eCWaoB aqgJrrj9VTAWm+w4dGlQasJuOq9fN3s= X-Authority-Analysis: v=2.4 cv=DJe/JSNb c=1 sm=1 tr=0 ts=6a842040 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=iUiB7RZVDRUJM2x9xO4A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: 5Fi71tcEzR7BK4mU0cbSznpZYYJp6k4y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-17_04,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 spamscore=0 clxscore=1015 bulkscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608180066 On Mon, 2026-08-17 at 22:05 +0530, K Prateek Nayak wrote: > Hello Szabina, >=20 > On 8/17/2026 9:35 PM, Szabina Korbai wrote: > > Hello Peter, > >=20 > > We ran the same benchmarks (schbench, sysbench, hackbench) as > > Shubhang > > has on s390 on an LPAR running fedora 43 with 32 vCPUs. > >=20 > > We ran the benchmarks for each of the cgroup modes, and for the > > baseline, we chose the commit prior to the patches (f666241e6bd5 - > > sched/fair: Unify cfs_rq throttling via account_cfs_rq_runtime() ). > >=20 > > We have also tried running stress-ng in parallel with the > > benchmarks > > (set to generate 50% or 90% utilization for each vCPU). > >=20 > > Compared to simply running the benchmarks on their own, this has > > revealed some performance trade-offs that the move to a single > > runqueue > > can introduce. >=20 > Are you using tip:sched/core at commit 68e3748781 ("sched/fair: Fix > flat > hierarchy") for the flat_cg numbers or did you checkout at > 85570f10a4c6 > ("sched/eevdf: Move to a single runqueue")? >=20 > There are a couple fixes for vruntime update and Vincent's > optimizations > for preemption bits which might make a difference to the overall > results. Hi Prateek, thank you, that's a good call. I did checkout at "Move to a single runqueue". Let me try it with the fix included, see how the results are affected. Regards, --=20 Szabina Korbai Linux on Z development Software Labs Campus Unlimited Company 25 North Wall Quay, Dublin 1, D01 H104, Ireland szkorbai@linux.ibm.com IBM