From: Or Gerlitz <ogerlitz@Voltaire.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
Jamie Lokier <jamie@shareable.org>,
Anthony Liguori <anthony@codemonkey.ws>,
qemu-devel@nongnu.org, Jan Kiszka <jan.kiszka@web.de>,
Mark McLoughlin <markmc@redhat.com>, Dor Laor <dlaor@redhat.com>,
netdev@vger.kernel.org
Subject: Re: [Qemu-devel] [PATCH] net: add raw backend - some performance measurements
Date: Tue, 21 Jul 2009 14:05:32 +0300 [thread overview]
Message-ID: <4A65A0FC.6090204@Voltaire.com> (raw)
In-Reply-To: <20090721102733.GB22155@redhat.com>
Michael S. Tsirkin wrote:
> With raw sockets, send will block or fail if the TX queue for device is
> full. With tap+bridge, the buffer in tap has to fill up instead, which
> is not the same. I'm not sure this is the issue here, but could be: the
> benchmark is UDP, isn't it?
Michael,
What/where is this tap buffer? we're talking on VM TX, so looking on tun_get_user I see a call to
skb_copy_datagram_from_iovec() to copy from the user buffer to an skb, then a call to netif_rx_ni() and that's it... As for your question, indeed udp, the VM runs netperf/UDP_STREAM
Or.
next prev parent reply other threads:[~2009-07-21 11:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20090701162115.GA4555@shareable.org>
[not found] ` <4A4CA747.1050509@Voltaire.com>
[not found] ` <20090703023911.GD938@shareable.org>
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[not found] ` <4A647B72.5090404@Voltaire.com>
[not found] ` <20090720155308.GA9327@gondor.apana.org.au>
[not found] ` <4A656824.7070100@Voltaire.com>
2009-07-21 7:25 ` [Qemu-devel] [PATCH] net: add raw backend - some performance measurements Herbert Xu
2009-07-21 10:17 ` Or Gerlitz
2009-07-21 10:27 ` Michael S. Tsirkin
2009-07-21 11:05 ` Or Gerlitz [this message]
2009-07-21 12:01 ` Michael S. Tsirkin
2009-07-21 12:14 ` Herbert Xu
2009-07-21 13:41 ` Or Gerlitz
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