From: Jason Wang <[email protected]>
To: Stefan Hajnoczi <[email protected]>
Cc: Stefan Hajnoczi <[email protected]>,
Yongji Xie <[email protected]>,
"Michael S. Tsirkin" <[email protected]>,
Ming Lei <[email protected]>,
Ziyang Zhang <[email protected]>,
[email protected], [email protected],
linux-kernel <[email protected]>,
"Denis V. Lunev" <[email protected]>,
Xiaoguang Wang <[email protected]>
Subject: Re: ublk-qcow2: ublk-qcow2 is available
Date: Fri, 4 Nov 2022 14:55:55 +0800 [thread overview]
Message-ID: <CACGkMEvBZDxTv-DS7V6HW+GPZio5jiafmNGACa2cyWqCr_GvJg@mail.gmail.com> (raw)
In-Reply-To: <Y2LBa/ePKiSN2phm@fedora>
On Thu, Nov 3, 2022 at 3:13 AM Stefan Hajnoczi <[email protected]> wrote:
>
> On Tue, Nov 01, 2022 at 10:36:29AM +0800, Jason Wang wrote:
> > On Tue, Oct 25, 2022 at 8:02 PM Stefan Hajnoczi <[email protected]> wrote:
> > >
> > > On Tue, 25 Oct 2022 at 04:17, Yongji Xie <[email protected]> wrote:
> > > >
> > > > On Fri, Oct 21, 2022 at 2:30 PM Jason Wang <[email protected]> wrote:
> > > > >
> > > > >
> > > > > 在 2022/10/21 13:33, Yongji Xie 写道:
> > > > > > On Tue, Oct 18, 2022 at 10:54 PM Stefan Hajnoczi <[email protected]> wrote:
> > > > > >> On Tue, 18 Oct 2022 at 09:17, Yongji Xie <[email protected]> wrote:
> > > > > >>> On Tue, Oct 18, 2022 at 2:59 PM Ming Lei <[email protected]> wrote:
> > > > > >>>> On Mon, Oct 17, 2022 at 07:11:59PM +0800, Yongji Xie wrote:
> > > > > >>>>> On Fri, Oct 14, 2022 at 8:57 PM Ming Lei <[email protected]> wrote:
> > > > > >>>>>> On Thu, Oct 13, 2022 at 02:48:04PM +0800, Yongji Xie wrote:
> > > > > >>>>>>> On Wed, Oct 12, 2022 at 10:22 PM Stefan Hajnoczi <[email protected]> wrote:
> > > > > >>>>>>>> On Sat, 8 Oct 2022 at 04:43, Ziyang Zhang <[email protected]> wrote:
> > > > > >>>>>>>>> On 2022/10/5 12:18, Ming Lei wrote:
> > > > > >>>>>>>>>> On Tue, Oct 04, 2022 at 09:53:32AM -0400, Stefan Hajnoczi wrote:
> > > > > >>>>>>>>>>> On Tue, 4 Oct 2022 at 05:44, Ming Lei <[email protected]> wrote:
> > > > > >>>>>>>>>>>> On Mon, Oct 03, 2022 at 03:53:41PM -0400, Stefan Hajnoczi wrote:
> > > > > >>>>>>>>>>>>> On Fri, Sep 30, 2022 at 05:24:11PM +0800, Ming Lei wrote:
> > > There are ways to minimize that cost:
> > > 1. The driver only needs to fetch the device's sq index when it has
> > > run out of sq ring space.
> > > 2. The device can include sq index updates with completions. This is
> > > what NVMe does with the CQE SQ Head Pointer field, but the
> > > disadvantage is that the driver has no way of determining the sq index
> > > until a completion occurs.
> >
> > Probably, but as replied in another thread, based on the numbers
> > measured from the networking test, I think the current virtio layout
> > should be sufficient for block I/O but might not fit for cases like
> > NFV.
>
> I remember that the Linux virtio_net driver doesn't rely on vq spinlocks
> because CPU affinity and the NAPI architecture ensure that everything is
> CPU-local. There is no need to protect the freelist explicitly because
> the functions cannot race.
>
> Maybe virtio_blk can learn from virtio_net...
It only works for RX where add and get could be all done in NAPI. But
this is not the case for TX (and virtio-blk).
Actually, if the free_list is the one thing that needs to be
serialized, there's no need to use lock at all. We can try to switch
to use ptr_ring instead.
Thanks
>
> Stefan
next prev parent reply other threads:[~2022-11-04 6:57 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 9:24 ublk-qcow2: ublk-qcow2 is available Ming Lei
2022-10-03 19:53 ` Stefan Hajnoczi
2022-10-03 23:57 ` Denis V. Lunev
2022-10-05 15:11 ` Stefan Hajnoczi
2022-10-06 10:26 ` Ming Lei
2022-10-06 13:59 ` Stefan Hajnoczi
2022-10-06 15:09 ` Ming Lei
2022-10-06 18:29 ` Stefan Hajnoczi
2022-10-07 11:21 ` Ming Lei
2022-10-04 9:43 ` Ming Lei
2022-10-04 13:53 ` Stefan Hajnoczi
2022-10-05 4:18 ` Ming Lei
2022-10-05 12:21 ` Stefan Hajnoczi
2022-10-05 12:38 ` Denis V. Lunev
2022-10-06 11:24 ` Ming Lei
2022-10-07 10:04 ` Yongji Xie
2022-10-07 10:51 ` Ming Lei
2022-10-07 11:21 ` Yongji Xie
2022-10-07 11:23 ` Ming Lei
2022-10-08 8:43 ` Ziyang Zhang
2022-10-12 14:22 ` Stefan Hajnoczi
2022-10-13 6:48 ` Yongji Xie
2022-10-13 16:02 ` Stefan Hajnoczi
2022-10-14 12:56 ` Ming Lei
2022-10-17 11:11 ` Yongji Xie
2022-10-18 6:59 ` Ming Lei
2022-10-18 13:17 ` Yongji Xie
2022-10-18 14:54 ` Stefan Hajnoczi
2022-10-19 9:09 ` Ming Lei
2022-10-24 16:11 ` Stefan Hajnoczi
2022-10-21 5:33 ` Yongji Xie
2022-10-21 6:30 ` Jason Wang
2022-10-25 8:17 ` Yongji Xie
2022-10-25 12:02 ` Stefan Hajnoczi
2022-10-28 13:33 ` Yongji Xie
2022-11-01 2:36 ` Jason Wang
2022-11-02 19:13 ` Stefan Hajnoczi
2022-11-04 6:55 ` Jason Wang [this message]
2022-10-21 6:28 ` Jason Wang
2022-10-06 10:14 ` Richard W.M. Jones
2022-10-12 14:15 ` Stefan Hajnoczi
2022-10-13 1:50 ` Ming Lei
2022-10-13 16:01 ` Stefan Hajnoczi
2022-10-04 5:43 ` Manuel Bentele
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