From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 279F31EABAF for ; Fri, 8 Nov 2024 14:53:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731077620; cv=none; b=vBK1ohgn4jQ+40KToLIoaRvfp4gb1DqiEm6Ce+73CZLNcog/Ppf8+wWeJfcPYeuF+NhxUNEFOXSQnyiN8HC17ImbhcoLo8pmrtDxa+F99sWEZyedf7ab3Ne+AderCLO0swuKS76taUP0j/17MVSWOrPyF/sn0TbyGeH4rK7NKiA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731077620; c=relaxed/simple; bh=fZ5YazTZ03scJmw7IECcxO9xNDB5eI90rCdlN9V/APQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dmxtt4KE5xA/kXtEK9gsdN9aM4KY0AtDExn190bJzTmfeVqNDe9+Xja14Io+nKpiQMwGHpFaudt8frlZQRSjSKvKWH4Z1CV1fmamnuqthlZRE17B7voHUYDTvk5pxqiQL4Hmbp4bFZpuj18JaX3H/YHeaIjlvmDDwZI1/4XBapg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 46990339; Fri, 8 Nov 2024 06:54:08 -0800 (PST) Received: from [192.168.178.25] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 852333F528; Fri, 8 Nov 2024 06:53:35 -0800 (PST) Message-ID: Date: Fri, 8 Nov 2024 15:53:26 +0100 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 17/24] sched/fair: Implement delayed dequeue To: Phil Auld Cc: Peter Zijlstra , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, kprateek.nayak@amd.com, wuyun.abel@bytedance.com, youssefesmat@chromium.org, tglx@linutronix.de, efault@gmx.de References: <20240727102732.960974693@infradead.org> <20240727105030.226163742@infradead.org> <20241101124715.GA689589@pauld.westford.csb> <20241104125009.GA749675@pauld.westford.csb> From: Dietmar Eggemann Content-Language: en-US In-Reply-To: <20241104125009.GA749675@pauld.westford.csb> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 04/11/2024 13:50, Phil Auld wrote: > > Hi Dietmar, > > On Mon, Nov 04, 2024 at 10:28:37AM +0100 Dietmar Eggemann wrote: >> Hi Phil, >> >> On 01/11/2024 13:47, Phil Auld wrote: >>> >>> Hi Peterm [...] >> I'm not seeing this on my i7-13700K running tip sched/core (1a6151017ee5 >> - sched: psi: pass enqueue/dequeue flags to psi callbacks directly >> (2024-10-26 Johannes Weiner)) (6.12.0-rc4 - based) >> >> Using 'taskset 0xaaaaa' avoiding SMT and running only on P-cores. >> >> vanilla features: 990MB/s (mean out of 5 runs, σ: 9.38) >> NO_DELAY_DEQUEUE: 992MB/s (mean out of 5 runs, σ: 10.61) >> >> # sudo lshw -class disk -class storage >> *-nvme >> description: NVMe device >> product: GIGABYTE GP-ASM2NE6500GTTD >> vendor: Phison Electronics Corporation >> physical id: 0 >> bus info: pci@0000:01:00.0 >> logical name: /dev/nvme0 >> version: EGFM13.2 >> ... >> capabilities: nvme pciexpress msix msi pm nvm_express bus_master cap_list >> configuration: driver=nvme latency=0 nqn=nqn.2014.08.org.nvmexpress:19871987SN215108954872 GIGABYTE GP-ASM2NE6500GTTD state=live >> resources: irq:16 memory:70800000-70803fff >> >> # mount | grep ^/dev/nvme0 >> /dev/nvme0n1p2 on / type ext4 (rw,relatime,errors=remount-ro) >> >> Which disk device you're using? > > Most of the reports are on various NVME drives (samsung mostly I think). > > > One thing I should add is that it's all on LVM: > > > vgcreate vg /dev/nvme0n1 -y > lvcreate -n thinMeta -L 3GB vg -y > lvcreate -n thinPool -l 99%FREE vg -y > lvconvert --thinpool /dev/mapper/vg-thinPool --poolmetadata /dev/mapper/vg-thinMeta -Zn -y > lvcreate -n testLV -V 1300G --thinpool thinPool vg > wipefs -a /dev/mapper/vg-testLV > mkfs.ext4 /dev/mapper/vg-testLV -E lazy_itable_init=0,lazy_journal_init=0 -F > mount /dev/mapper/vg-testLV /testfs > > > With VDO or thinpool (as above) it shows on both ext4 and xfs. With fs on > drive directly it's a little more variable. Some it shows on xfs, some it show > on ext4 and not vice-versa, seems to depend on the drive or hw raid. But when > it shows it's 100% reproducible on that setup. > > It's always the randwrite numbers. The rest look fine. > > Also, as yet I'm not personally doing this testing, just looking into it and > passing on the information I have. One reason I don't see the difference between DELAY_DEQUEUE and NO_DELAY_DEQUEUE could be because of the affinity of the related nvme interrupts: $ cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7 CPU8 ... 132: 0 0 1523653 0 0 0 0 0 0 ... IR-PCI-MSIX-0000:01:00.0 1-edge nvme0q1 133: 0 0 0 0 0 1338451 0 0 0 ... IR-PCI-MSIX-0000:01:00.0 2-edge nvme0q2 134: 0 0 0 0 0 0 0 0 2252297 ... IR-PCI-MSIX-0000:01:00.0 3-edge nvme0q3 $ cat /proc/irq/132/smp_affinity_list 0-2 cat /proc/irq/133/smp_affinity_list 3-5 cat /proc/irq/134/smp_affinity_list 6-8 So the 8 fio tasks from: # fio --cpus_allowed 1,2,3,4,5,6,7,8 --rw randwrite --bs 4k --runtime 8s --iodepth 32 --direct 1 --ioengine libaio --numjobs 8 --size 30g --name default --time_based --group_reporting --cpus_allowed_policy shared --directory /testfs don't have to fight with per-CPU kworkers on each CPU. e.g. 'nvme0q3 interrupt -> queue on workqueue dio/nvme0n1p2 -> run iomap_dio_complete_work() in kworker/8:x' In case I trace the 'task_on_rq_queued(p) && p->se.sched_delayed && rq->nr_running > 1) condition in ttwu_runnable() condition i only see the per-CPU kworker in there, so p->nr_cpus_allowed == 1. So the patch shouldn't make a difference for this scenario? But maybe your VDO or thinpool setup creates waker/wakee pairs with wakee->nr_cpus_allowed > 1? Does your machine has single CPU smp_affinity masks for these nvme interrupts? [...]