From: Paolo Bonzini <pbonzini@redhat.com>
To: Vincenzo Maffione <v.maffione@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
Markus Armbruster <armbru@redhat.com>,
Giuseppe Lettieri <g.lettieri@iet.unipi.it>,
Luigi Rizzo <rizzo@iet.unipi.it>
Subject: Re: [Qemu-devel] [PATCH v2 0/3] virtio: proposal to optimize accesses to VQs
Date: Wed, 16 Dec 2015 10:34:06 +0100 [thread overview]
Message-ID: <5671300E.5060109@redhat.com> (raw)
In-Reply-To: <CA+_eA9hp4dr14aM0TaPCrNks-K8ik-Ma+bn74N-1XAipR69wbQ@mail.gmail.com>
On 16/12/2015 10:28, Vincenzo Maffione wrote:
> Assuming my TX experiments with disconnected backend (and I disable
> CPU dynamic scaling of performance, etc.):
> 1) after patch 1 and 2, virtio bottleneck jumps from ~1Mpps to 1.910 Mpps.
> 2) after patch 1,2 and 3, virtio bottleneck jumps to 2.039 Mpps.
>
> So I see an improvement for patch 3, and I guess it's because we avoid
> an additional memory translation and related overhead. I believe that
> avoiding the memory translation is more beneficial than avoiding the
> variable-sized memcpy.
> I'm not surprised of that, because taking a brief look at what happens
> under the hood when you call an access_memory() function - it looks
> like a lot of operations.
Great, thanks for confirming!
Paolo
next prev parent reply other threads:[~2015-12-16 9:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-15 22:33 [Qemu-devel] [PATCH v2 0/3] virtio: proposal to optimize accesses to VQs Vincenzo Maffione
2015-12-15 22:33 ` [Qemu-devel] [PATCH v2 1/3] virtio: cache used_idx in a VirtQueue field Vincenzo Maffione
2015-12-15 22:33 ` [Qemu-devel] [PATCH v2 2/3] virtio: read avail_idx from VQ only when necessary Vincenzo Maffione
2015-12-15 22:33 ` [Qemu-devel] [PATCH v2 3/3] virtio: combine write of an entry into used ring Vincenzo Maffione
2015-12-16 8:38 ` [Qemu-devel] [PATCH v2 0/3] virtio: proposal to optimize accesses to VQs Paolo Bonzini
2015-12-16 9:28 ` Vincenzo Maffione
2015-12-16 9:34 ` Paolo Bonzini [this message]
2015-12-16 10:39 ` Vincenzo Maffione
2015-12-16 11:02 ` Michael S. Tsirkin
2015-12-16 11:23 ` Vincenzo Maffione
2015-12-16 11:37 ` Paolo Bonzini
2015-12-16 14:25 ` Vincenzo Maffione
2015-12-16 15:46 ` Paolo Bonzini
2015-12-30 16:45 ` Vincenzo Maffione
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