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From: Stefan Hajnoczi <stefanha@redhat.com>
To: Mike Christie <michael.christie@oracle.com>
Cc: target-devel@vger.kernel.org, linux-scsi@vger.kernel.org,
	pbonzini@redhat.com, jasowang@redhat.com, mst@redhat.com,
	sgarzare@redhat.com, virtualization@lists.linux-foundation.org
Subject: Re: vhost: multiple worker support
Date: Thu, 3 Jun 2021 11:13:57 +0100	[thread overview]
Message-ID: <YLirZVVeL95jm2/O@stefanha-x1.localdomain> (raw)
In-Reply-To: <20210525180600.6349-1-michael.christie@oracle.com>

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On Tue, May 25, 2021 at 01:05:51PM -0500, Mike Christie wrote:
> Results:
> --------
> When running with the null_blk driver and vhost-scsi I can get 1.2
> million IOPs by just running a simple
> 
> fio --filename=/dev/sda --direct=1 --rw=randrw --bs=4k --ioengine=libaio
> --iodepth=128  --numjobs=8 --time_based --group_reporting --name=iops
> --runtime=60 --eta-newline=1
> 
> The VM has 8 vCPUs and sda has 8 virtqueues and we can do a total of
> 1024 cmds per devices. To get 1.2 million IOPs I did have to tune and
> ran the virsh emulatorpin command so the vhost threads were running
> on different CPUs than the VM. If the vhost threads share CPUs then I
> get around 800K.
> 
> For a more real device that are also CPU hogs like iscsi, I can still
> get 1 million IOPs using 1 dm-multipath device over 8 iscsi paths
> (natively it gets 1.1 million IOPs).

There is no comparison against a baseline, but I guess it would be the
same 8 vCPU guest with single queue vhost-scsi?

> 
> Results/TODO Note:
> 
> - I ported the vdpa sim code to support multiple workers and as-is now
> it made perf much worse. If I increase vdpa_sim_blk's num queues to 4-8
> I get 700K IOPs with the fio command above. However with the multiple
> worker support it drops to 400K. The problem is the vdpa_sim lock
> and the iommu_lock. If I hack (like comment out locks or not worry about
> data corruption or crashes) then I can get around 1.2M - 1.6M IOPs with
> 8 queues and fio command above.
> 
> So these patches could help other drivers, but it will just take more
> work to remove those types of locks. I was hoping the 2 items could be
> done indepentently since it helps vhost-scsi immediately.

Cool, thank you for taking a look. That's useful info for Stefano. vDPA
and vhost can be handled independently though in the long term hopefully
they can share code.

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  parent reply	other threads:[~2021-06-03 10:14 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 18:05 vhost: multiple worker support Mike Christie
2021-05-25 18:05 ` [PATCH 1/9] vhost: move worker thread fields to new struct Mike Christie
2021-06-03 10:16   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 2/9] vhost: move vhost worker creation to kick setup Mike Christie
2021-06-03 10:28   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 3/9] vhost: modify internal functions to take a vhost_worker Mike Christie
2021-06-03 10:45   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 4/9] vhost: allow vhost_polls to use different vhost_workers Mike Christie
2021-06-03 13:51   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 5/9] vhost-scsi: flush IO vqs then send TMF rsp Mike Christie
2021-06-03 13:54   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 6/9] vhost-scsi: make SCSI cmd completion per vq Mike Christie
2021-06-03 13:57   ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 7/9] vhost: allow userspace to create workers Mike Christie
2021-06-03 14:30   ` Stefan Hajnoczi
2021-06-05 23:53     ` michael.christie
2021-06-07 15:19       ` Stefan Hajnoczi
2021-06-09 21:03         ` Mike Christie
2021-06-10  8:06           ` Stefan Hajnoczi
2021-06-18  2:49             ` Mike Christie
2021-06-21 13:41               ` Stefan Hajnoczi
2021-05-25 18:05 ` [PATCH 8/9] vhost: add vhost_dev pointer to vhost_work Mike Christie
2021-06-03 14:31   ` Stefan Hajnoczi
2021-05-25 18:06 ` [PATCH 9/9] vhost: support sharing workers across devs Mike Christie
2021-06-03 14:32   ` Stefan Hajnoczi
2021-06-07  2:18     ` Jason Wang
2021-06-03 10:13 ` Stefan Hajnoczi [this message]
2021-06-03 18:45   ` vhost: multiple worker support Mike Christie
2021-06-03 14:37 ` Stefan Hajnoczi
2021-06-03 22:16   ` Mike Christie
2021-06-05 22:40     ` michael.christie
2021-06-07 15:23       ` Stefan Hajnoczi

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