From: Stephen Hemminger <shemminger@vyatta.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Jason Wang <jasowang@redhat.com>,
netdev@vger.kernel.org, rusty@rustcorp.com.au,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] virtio-net: fix a race on 32bit arches
Date: Wed, 6 Jun 2012 08:14:32 -0700 [thread overview]
Message-ID: <20120606081432.6b602065@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <20120606144941.GA17092@redhat.com>
On Wed, 6 Jun 2012 17:49:42 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> Sounds good, but I have a question: this realies on counters
> being atomic on 64 bit.
> Would not it be better to always use a seqlock even on 64 bit?
> This way counters would actually be correct and in sync.
> As it is if we want e.g. average packet size,
> we can not rely e.g. on it being bytes/packets.
This has not been a requirement on real physical devices; therefore
the added overhead is not really justified.
Many network cards use counters in hardware to count packets/bytes
and there is no expectation of atomic access there.
next prev parent reply other threads:[~2012-06-06 15:14 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-06 8:35 [PATCH] virtio-net: fix a race on 32bit arches Eric Dumazet
2012-06-06 8:45 ` Eric Dumazet
2012-06-06 9:37 ` Jason Wang
2012-06-06 11:13 ` Michael S. Tsirkin
2012-06-06 13:10 ` Eric Dumazet
2012-06-06 14:49 ` Michael S. Tsirkin
2012-06-06 15:14 ` Stephen Hemminger [this message]
2012-06-06 18:51 ` Michael S. Tsirkin
2012-06-06 19:54 ` Eric Dumazet
2012-06-06 19:58 ` Michael S. Tsirkin
2012-06-06 20:08 ` Eric Dumazet
2012-06-06 20:16 ` Michael S. Tsirkin
2012-06-06 20:24 ` Eric Dumazet
2012-06-06 20:38 ` Eric Dumazet
2012-06-06 20:35 ` Ben Hutchings
2012-06-06 20:43 ` Michael S. Tsirkin
2012-06-06 20:19 ` Ben Hutchings
2012-06-06 20:25 ` Eric Dumazet
2012-06-06 15:19 ` Eric Dumazet
2012-06-06 16:17 ` Michael S. Tsirkin
2012-06-06 17:13 ` Eric Dumazet
2012-06-06 18:43 ` Michael S. Tsirkin
2012-06-06 20:06 ` Eric Dumazet
2012-06-06 20:19 ` Michael S. Tsirkin
2012-06-06 16:57 ` Michael S. Tsirkin
2012-06-06 20:00 ` Eric Dumazet
2012-06-10 6:36 ` Rusty Russell
2012-06-10 7:03 ` Michael S. Tsirkin
2012-06-10 10:21 ` Eric Dumazet
2012-06-10 10:22 ` Michael S. Tsirkin
2012-06-10 10:25 ` Michael S. Tsirkin
2012-06-11 3:23 ` David Miller
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