From: Stefano Garzarella <sgarzare@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <fam@euphon.net>,
Eduardo Habkost <ehabkost@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
cohuck@redhat.com, qemu-devel@nongnu.org,
Max Reitz <mreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v2 0/4] virtio-pci: enable blk and scsi multi-queue by default
Date: Mon, 27 Jan 2020 10:59:42 +0100 [thread overview]
Message-ID: <20200127095942.4n4ikvfptirqhn7c@steredhat> (raw)
In-Reply-To: <20200124100159.736209-1-stefanha@redhat.com>
On Fri, Jan 24, 2020 at 10:01:55AM +0000, Stefan Hajnoczi wrote:
> v2:
> * Let the virtio-DEVICE-pci device select num-queues because the optimal
> multi-queue configuration may differ between virtio-pci, virtio-mmio, and
> virtio-ccw [Cornelia]
>
> Enabling multi-queue on virtio-pci storage devices improves performance on SMP
> guests because the completion interrupt is handled on the vCPU that submitted
> the I/O request. This avoids IPIs inside the guest.
>
> Note that performance is unchanged in these cases:
> 1. Uniprocessor guests. They don't have IPIs.
> 2. Application threads might be scheduled on the sole vCPU that handles
> completion interrupts purely by chance. (This is one reason why benchmark
> results can vary noticably between runs.)
> 3. Users may bind the application to the vCPU that handles completion
> interrupts.
>
> Set the number of queues to the number of vCPUs by default. Older machine
> types continue to default to 1 queue for live migration compatibility.
>
> This patch improves IOPS by 1-4% on an Intel Optane SSD with 4 vCPUs, -drive
> aio=native, and fio bs=4k direct=1 rw=randread.
>
> Stefan Hajnoczi (4):
> virtio-scsi: introduce a constant for fixed virtqueues
> virtio-scsi: default num_queues to -smp N
> virtio-blk: default num_queues to -smp N
> vhost-user-blk: default num_queues to -smp N
The series looks good to me:
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Thanks,
Stefano
prev parent reply other threads:[~2020-01-27 10:00 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-24 10:01 [PATCH v2 0/4] virtio-pci: enable blk and scsi multi-queue by default Stefan Hajnoczi
2020-01-24 10:01 ` [PATCH v2 1/4] virtio-scsi: introduce a constant for fixed virtqueues Stefan Hajnoczi
2020-01-27 12:59 ` Cornelia Huck
2020-01-24 10:01 ` [PATCH v2 2/4] virtio-scsi: default num_queues to -smp N Stefan Hajnoczi
2020-01-27 13:10 ` Cornelia Huck
2020-01-29 15:44 ` Stefan Hajnoczi
2020-01-30 0:29 ` Paolo Bonzini
2020-01-30 10:52 ` Stefan Hajnoczi
2020-01-30 11:03 ` Cornelia Huck
2020-02-03 10:25 ` Sergio Lopez
2020-02-03 10:35 ` Michael S. Tsirkin
2020-02-03 10:51 ` Cornelia Huck
2020-02-03 10:57 ` Daniel P. Berrangé
2020-02-03 11:39 ` Sergio Lopez
2020-02-03 12:53 ` Michael S. Tsirkin
2020-02-11 16:20 ` Stefan Hajnoczi
2020-02-11 16:31 ` Michael S. Tsirkin
2020-02-12 11:18 ` Stefan Hajnoczi
2020-02-21 10:55 ` Stefan Hajnoczi
2020-01-24 10:01 ` [PATCH v2 3/4] virtio-blk: " Stefan Hajnoczi
2020-01-27 13:14 ` Cornelia Huck
2020-01-24 10:01 ` [PATCH v2 4/4] vhost-user-blk: " Stefan Hajnoczi
2020-01-27 13:17 ` Cornelia Huck
2020-01-27 9:59 ` Stefano Garzarella [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200127095942.4n4ikvfptirqhn7c@steredhat \
--to=sgarzare@redhat.com \
--cc=cohuck@redhat.com \
--cc=ehabkost@redhat.com \
--cc=fam@euphon.net \
--cc=kwolf@redhat.com \
--cc=mreitz@redhat.com \
--cc=mst@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).