From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [PATCH] virtio-net: fix a race on 32bit arches
Date: Wed, 6 Jun 2012 23:19:43 +0300 [thread overview]
Message-ID: <20120606201942.GA23405@redhat.com> (raw)
In-Reply-To: <1339013171.26966.60.camel@edumazet-glaptop>
On Wed, Jun 06, 2012 at 10:06:11PM +0200, Eric Dumazet wrote:
> On Wed, 2012-06-06 at 21:43 +0300, Michael S. Tsirkin wrote:
>
> > 1. We are trying to look at counters for purposes of tuning the device.
> > E.g. if ethtool reports packets and bytes, we'd like to calculate
> > average packet size by bytes/packets.
> >
> > If both counters are read atomically the metric becomes more exact.
> > Not a must but nice to have.
> >
>
> metrics are exact right now.
Yes, but they are not synchronised between themselves.
E.g. you can in theory have a report where #of packets > #of bytes.
I know there's no guarantee they are synchronised
on an arbitrary device but if they are, without
slowing fast path, it's nice.
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>,
netdev@vger.kernel.org, rusty@rustcorp.com.au,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [PATCH] virtio-net: fix a race on 32bit arches
Date: Wed, 6 Jun 2012 23:19:43 +0300 [thread overview]
Message-ID: <20120606201942.GA23405@redhat.com> (raw)
In-Reply-To: <1339013171.26966.60.camel@edumazet-glaptop>
On Wed, Jun 06, 2012 at 10:06:11PM +0200, Eric Dumazet wrote:
> On Wed, 2012-06-06 at 21:43 +0300, Michael S. Tsirkin wrote:
>
> > 1. We are trying to look at counters for purposes of tuning the device.
> > E.g. if ethtool reports packets and bytes, we'd like to calculate
> > average packet size by bytes/packets.
> >
> > If both counters are read atomically the metric becomes more exact.
> > Not a must but nice to have.
> >
>
> metrics are exact right now.
Yes, but they are not synchronised between themselves.
E.g. you can in theory have a report where #of packets > #of bytes.
I know there's no guarantee they are synchronised
on an arbitrary device but if they are, without
slowing fast path, it's nice.
next prev parent reply other threads:[~2012-06-06 20:19 UTC|newest]
Thread overview: 64+ 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 8:35 ` Eric Dumazet
2012-06-06 8:45 ` Eric Dumazet
2012-06-06 8:45 ` Eric Dumazet
2012-06-06 9:37 ` Jason Wang
2012-06-06 9:37 ` Jason Wang
2012-06-06 11:13 ` Michael S. Tsirkin
2012-06-06 11:13 ` Michael S. Tsirkin
2012-06-06 13:10 ` Eric Dumazet
2012-06-06 13:10 ` Eric Dumazet
2012-06-06 14:49 ` Michael S. Tsirkin
2012-06-06 14:49 ` Michael S. Tsirkin
2012-06-06 15:14 ` Stephen Hemminger
2012-06-06 15:14 ` Stephen Hemminger
2012-06-06 18:51 ` Michael S. Tsirkin
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 19:58 ` Michael S. Tsirkin
2012-06-06 20:08 ` Eric Dumazet
2012-06-06 20:08 ` Eric Dumazet
2012-06-06 20:16 ` Michael S. Tsirkin
2012-06-06 20:16 ` Michael S. Tsirkin
2012-06-06 20:24 ` Eric Dumazet
2012-06-06 20:24 ` Eric Dumazet
2012-06-06 20:38 ` Eric Dumazet
2012-06-06 20:38 ` Eric Dumazet
2012-06-06 20:35 ` Ben Hutchings
2012-06-06 20:35 ` Ben Hutchings
2012-06-06 20:43 ` Michael S. Tsirkin
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 20:25 ` Eric Dumazet
2012-06-06 20:19 ` Ben Hutchings
2012-06-06 19:54 ` Eric Dumazet
2012-06-06 15:19 ` Eric Dumazet
2012-06-06 15:19 ` Eric Dumazet
2012-06-06 16:17 ` Michael S. Tsirkin
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 18:43 ` Michael S. Tsirkin
2012-06-06 20:06 ` Eric Dumazet
2012-06-06 20:06 ` Eric Dumazet
2012-06-06 20:19 ` Michael S. Tsirkin [this message]
2012-06-06 20:19 ` Michael S. Tsirkin
2012-06-06 17:13 ` Eric Dumazet
2012-06-06 16:57 ` Michael S. Tsirkin
2012-06-06 16:57 ` Michael S. Tsirkin
2012-06-06 20:00 ` Eric Dumazet
2012-06-06 20:00 ` Eric Dumazet
2012-06-10 6:36 ` Rusty Russell
2012-06-10 6:36 ` Rusty Russell
2012-06-10 7:03 ` Michael S. Tsirkin
2012-06-10 7:03 ` Michael S. Tsirkin
2012-06-10 10:21 ` Eric Dumazet
2012-06-10 10:21 ` Eric Dumazet
2012-06-10 10:22 ` Michael S. Tsirkin
2012-06-10 10:22 ` Michael S. Tsirkin
2012-06-10 10:25 ` Michael S. Tsirkin
2012-06-10 10:25 ` Michael S. Tsirkin
2012-06-11 3:23 ` David Miller
2012-06-11 3:23 ` David Miller
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