From: Matt Wilson <msw@amazon.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
xen-devel <xen-devel@lists.xen.org>
Subject: Re: [Hackathon minutes] PV block improvements
Date: Mon, 24 Jun 2013 23:09:19 -0700 [thread overview]
Message-ID: <20130625060917.GA5287@u109add4315675089e695.ant.amazon.com> (raw)
In-Reply-To: <51C54E18.6020303@citrix.com>
On Sat, Jun 22, 2013 at 09:11:20AM +0200, Roger Pau Monné wrote:
> On 21/06/13 20:07, Matt Wilson wrote:
> > On Fri, Jun 21, 2013 at 07:10:59PM +0200, Roger Pau Monné wrote:
[...]
> >> 2. Switch to grant copy in blkback, and get rid of persistent grants (I
> >> have not benchmarked this solution, but I'm quite sure it will involve a
> >> performance regression, specially when scaling to a high number of domains).
> >
> > Why do you think so?
>
> First because grant_copy is done by the hypervisor, while when using
> persistent grants the copy is done by the guest. Also, grant_copy takes
> the grant lock, so when scaling to a large number of domains there's
> going to be contention around this lock. Persistent grants don't need
> any shared lock, and thus scale better.
It'd benefit xen-netback to make the locking in the copy path more
fine grained. That would help multi-vif domUs today, and multi-queue
vifs later on.
Thoughts?
--msw
next prev parent reply other threads:[~2013-06-25 6:09 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-24 15:06 [Hackathon minutes] PV block improvements Roger Pau Monné
2013-06-21 17:10 ` Roger Pau Monné
2013-06-21 18:07 ` Matt Wilson
2013-06-22 7:11 ` Roger Pau Monné
2013-06-25 6:09 ` Matt Wilson [this message]
2013-06-25 13:01 ` Wei Liu
2013-06-25 15:39 ` Matt Wilson
2013-06-25 15:53 ` Ian Campbell
2013-06-25 18:04 ` Stefano Stabellini
2013-06-26 9:37 ` George Dunlap
2013-06-26 11:37 ` Ian Campbell
2013-06-27 13:58 ` George Dunlap
2013-06-27 14:21 ` Ian Campbell
2013-06-27 15:20 ` Roger Pau Monné
2013-06-25 15:57 ` Ian Campbell
2013-06-25 16:05 ` Jan Beulich
2013-06-25 16:30 ` Roger Pau Monné
2013-06-27 15:12 ` Roger Pau Monné
2013-06-27 15:26 ` Stefano Stabellini
2013-06-21 20:16 ` Konrad Rzeszutek Wilk
2013-06-21 23:17 ` Wei Liu
2013-06-24 11:06 ` Stefano Stabellini
2013-07-02 11:49 ` Roger Pau Monné
2013-06-22 7:17 ` Roger Pau Monné
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