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From: Ming Lei <tom.leiming@gmail.com>
To: Keith Busch <keith.busch@gmail.com>
Cc: Ming Lei <ming.lei@redhat.com>, Long Li <longli@microsoft.com>,
	Jens Axboe <axboe@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
	chenxiang <chenxiang66@hisilicon.com>,
	Peter Zijlstra <peterz@infradead.org>,
	John Garry <john.garry@huawei.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-nvme <linux-nvme@lists.infradead.org>,
	Keith Busch <keith.busch@intel.com>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Christoph Hellwig <hch@lst.de>,
	"longli@linuxonhyperv.com" <longli@linuxonhyperv.com>
Subject: Re: [PATCH 0/3] fix interrupt swamp in NVMe
Date: Thu, 22 Aug 2019 10:23:16 +0800	[thread overview]
Message-ID: <CACVXFVOwH+fA5tYUG+Bacf-zzbH+=itA+edCVgvaZ4nNHAt6zA@mail.gmail.com> (raw)
In-Reply-To: <CAOSXXT7LVjBqVW14y-pZyUCat3PBPd_nVd_uDahBdhyW+eHmcg@mail.gmail.com>

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On Thu, Aug 22, 2019 at 10:00 AM Keith Busch <keith.busch@gmail.com> wrote:
>
> On Wed, Aug 21, 2019 at 7:34 PM Ming Lei <ming.lei@redhat.com> wrote:
> > On Wed, Aug 21, 2019 at 04:27:00PM +0000, Long Li wrote:
> > > Here is the command to benchmark it:
> > >
> > > fio --bs=4k --ioengine=libaio --iodepth=128 --filename=/dev/nvme0n1:/dev/nvme1n1:/dev/nvme2n1:/dev/nvme3n1:/dev/nvme4n1:/dev/nvme5n1:/dev/nvme6n1:/dev/nvme7n1:/dev/nvme8n1:/dev/nvme9n1 --direct=1 --runtime=120 --numjobs=80 --rw=randread --name=test --group_reporting --gtod_reduce=1
> > >
> >
> > I can reproduce the issue on one machine(96 cores) with 4 NVMes(32 queues), so
> > each queue is served on 3 CPUs.
> >
> > IOPS drops > 20% when 'use_threaded_interrupts' is enabled. From fio log, CPU
> > context switch is increased a lot.
>
> Interestingly use_threaded_interrupts shows a marginal improvement on
> my machine with the same fio profile. It was only 5 NVMes, but they've
> one queue per-cpu on 112 cores.

Not investigate it yet.

BTW, my fio test is only done on the single hw queue via 'taskset -c
$cpu_list_of_the_queue',
without applying the threaded interrupt affinity patch. NVMe is Optane.

The same issue can be reproduced after I force to use 1:1 mapping via passing
'possible_cpus=32' kernel cmd line.

Maybe related with kernel options, so attache the one I used, and
basically it is
a subset of RHEL8 kernel.

Thanks,
Ming Lei

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  reply	other threads:[~2019-08-22  2:23 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20  6:14 [PATCH 0/3] fix interrupt swamp in NVMe longli
2019-08-20  6:14 ` [PATCH 1/3] sched: define a function to report the number of context switches on a CPU longli
2019-08-20  9:38   ` Peter Zijlstra
2019-08-21  8:20     ` Long Li
2019-08-21 10:34       ` Peter Zijlstra
2019-08-20  9:39   ` Peter Zijlstra
2019-08-20  6:14 ` [PATCH 2/3] sched: export idle_cpu() longli
2019-08-20  6:14 ` [PATCH 3/3] nvme: complete request in work queue on CPU with flooded interrupts longli
2019-08-20  9:52   ` Peter Zijlstra
2019-08-21  8:37     ` Long Li
2019-08-21 10:35       ` Peter Zijlstra
2019-08-20 17:33   ` Sagi Grimberg
2019-08-21  8:39     ` Long Li
2019-08-21 17:36       ` Long Li
2019-08-21 21:54         ` Sagi Grimberg
2019-08-24  0:13           ` Long Li
2019-08-23  3:21     ` Ming Lei
2019-08-24  0:27       ` Long Li
2019-08-24 12:55         ` Ming Lei
2019-08-20  8:25 ` [PATCH 0/3] fix interrupt swamp in NVMe Ming Lei
2019-08-20  8:59   ` John Garry
2019-08-20 15:05     ` Keith Busch
2019-08-21  7:47     ` Long Li
2019-08-21  9:44       ` Ming Lei
2019-08-21 10:03         ` John Garry
2019-08-21 16:27         ` Long Li
2019-08-22  1:33           ` Ming Lei
2019-08-22  2:00             ` Keith Busch
2019-08-22  2:23               ` Ming Lei [this message]
2019-08-22  9:48               ` Thomas Gleixner

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