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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Shirley Ma <mashirle@us.ibm.com>
Cc: David Miller <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Avi Kivity <avi@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
	netdev@vger.kernel.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V5 4/6 net-next] vhost: vhost TX zero-copy support
Date: Mon, 16 May 2011 23:45:40 +0300	[thread overview]
Message-ID: <20110516204540.GD18148@redhat.com> (raw)
In-Reply-To: <1305574484.3456.30.camel@localhost.localdomain>

> +/* Since we need to keep the order of used_idx as avail_idx, it's possible that
> + * DMA done not in order in lower device driver for some reason. To prevent
> + * used_idx out of order, upend_idx is used to track avail_idx order, done_idx
> + * is used to track used_idx order. Once lower device DMA done, then upend_idx
> + * can move to done_idx.

Could you clarify this please? virtio explicitly allows out of order
completion of requests. Does it simplify code that we try to keep
used index updates in-order? Because if not, this is not
really a requirement.

-- 
MST

  reply	other threads:[~2011-05-16 20:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-16 19:34 [PATCH V5 4/6 net-next] vhost: vhost TX zero-copy support Shirley Ma
2011-05-16 20:45 ` Michael S. Tsirkin [this message]
2011-05-16 20:56   ` Shirley Ma
2011-05-16 21:24     ` Michael S. Tsirkin
2011-05-16 21:30       ` Shirley Ma
2011-05-17  4:31       ` Shirley Ma
2011-05-17  5:55         ` Michael S. Tsirkin
2011-05-17 15:22           ` Shirley Ma
2011-05-17 15:28             ` Michael S. Tsirkin
2011-05-17 15:34               ` Shirley Ma
2011-05-17 20:46                 ` [TEST PATCH net-next] vhost: accumulate multiple used and sigal in vhost TX test Shirley Ma
2011-05-17 20:52                   ` Michael S. Tsirkin
2011-05-17 20:50                 ` [PATCH V5 4/6 net-next] vhost: vhost TX zero-copy support Shirley Ma
2011-05-17 20:58                   ` Michael S. Tsirkin
2011-05-17 21:01                     ` Shirley Ma
2011-05-17 21:28                   ` Michael S. Tsirkin
2011-05-17 22:21                     ` Shirley Ma
2011-05-18  5:14                     ` Shirley Ma
2011-05-18  6:16                       ` [PATCH V6 " Shirley Ma
2011-05-18  8:43                         ` Michael S. Tsirkin
2011-05-18  8:32                       ` [PATCH V5 " Michael S. Tsirkin
2011-05-18  8:45                       ` Michael S. Tsirkin
2011-05-16 21:27     ` Michael S. Tsirkin

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