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Tue, 28 Jul 2026 14:53:30 +0000 (GMT) From: Alok Rathore To: wangyang.guo@intel.com Cc: akpm@linux-foundation.org, axboe@fb.com, dan.liang@intel.com, hch@lst.de, kbusch@kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, ming.lei@redhat.com, rrendec@redhat.com, sagi@grimberg.me, tglx@linutronix.de, tianyou.li@intel.com, tim.c.chen@linux.intel.com, virtualization@lists.linux-foundation.org, asml.silence@gmail.com, cpgs@samsung.com, gost.dev@samsung.com, alokrathore20@gmail.com, nitheshshetty@gmail.com, Alok Rathore Subject: Re: [PATCH v2] lib/group_cpus: make group CPU cluster aware Date: Tue, 28 Jul 2026 20:23:03 +0530 Message-Id: <561480862.11785314102640.JavaMail.epsvc@epcpadp1new> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260113022958.3379650-1-wangyang.guo@intel.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CMS-MailID: 20260728145333epcas5p427c6b6d72bff02de3f29e6a6a2108958 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P X-CPGSPASS: Y X-Hop-Count: 3 X-CMS-RootMailID: 20260728145333epcas5p427c6b6d72bff02de3f29e6a6a2108958 References: <20260113022958.3379650-1-wangyang.guo@intel.com> For higher number of jobs(>=64), we are seeing ~8% regression with this patch. Tool: fio with io_uring engine [1] +------------+------------+-------------------+ | numjobs | before | after patch | +------------+------------+-------------------+ | 1 | 89 | 88.8 (-0.22%) | | 2 | 169 | 168 (-0.59%) | | 4 | 338 | 337 (-0.30%) | | 8 | 533 | 533 (0.00%) | | 16 | 538 | 541 (+0.56%) | | 32 | 685 | 716 (+4.53%) | | 64 | 933 | 859 (-7.93%) | | 128 | 941 | 867 (-7.86%) | +------------+------------+-------------------+ * Metric: IOPS (K) (Block device, QD = 1, bs = 4K, Random Read) As shown in the table above, while performance is comparable at low job counts, there is a drop starting from 64 jobs after this patch. HW info: Intel(R) Core(TM) Ultra 7 265K CPU=20 IRQ-CPU are 1:1 mapped. [1] fio -filename=/dev/nvme0n1 -direct=1 -size=4g -rw=randread \ -numjobs=$(numjobs) -bs=4096 -ioengine=io_uring -iodepth=1 \ -name=uring_test --registerfiles=1 --ramp_time=5 \ --group_reporting --thread