From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v2 15/15] net: invoke qemu_can_send_packet only before
 net queue sending function
Date: Thu, 24 May 2012 14:02:26 +0200
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References: <1337786045-2277-1-git-send-email-zwu.kernel@gmail.com> <1337786045-2277-16-git-send-email-zwu.kernel@gmail.com> <4FBD0995.8030907@redhat.com> <CAEH94Lju+e1z4Fa1BTDM15A+LdfA68o9Yxjj303OcMdUHSp=XQ@mail.gmail.com> <4FBE085E.3060104@redhat.com> <CAEH94Lh-KK8tZ8g4G6P__kdLygZ_KCbE7HagG7TYOVEs+cB-zg@mail.gmail.com>
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To: Zhi Yong Wu <zwu.kernel@gmail.com>
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Il 24/05/2012 13:58, Zhi Yong Wu ha scritto:
>> > But you will copy packets uselessly.  The code before the patch simply
>> > left them on the tap file descriptor.  This is better because it
>> > involves the kernel in flow control.  You are introducing "bufferbloat".
> You are correct, but can_send_packet will be invoked twice for one
> packet delivery.

Doesn't matter, it's cheap.

Paolo