From: William Dauchy <william@gandi.net>
Subject: Re: [PATCH v3 1/3][xen-netback] add a pseudo pps rate
 limit
Date: Tue, 9 Jul 2013 16:01:17 +0200
Message-ID: <20130709140117.GN20956@gandi.net>
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To: Sander Eikelenboom <linux@eikelenboom.it>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Campbell <Ian.Campbell@citrix.com>, William Dauchy <william@gandi.net>, Ahmed Amamou <ahmed@gandi.net>, xen-devel <xen-devel@lists.xen.org>, Kamel Haddadou <kamel@gandi.net>
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On Jul09 15:48, Sander Eikelenboom wrote:
> Just wondering, why should this be done in the drivers ?
> Couldn't this also be achieved with netfilter and the recent/limit module=
s ?
> The limit module can already handle bursts.

We indeed forgot to talk about it since we already got the question from
Wei.
The first thing is that your comment is also true for bandwidth which is
already present. Moreover PPS is linked to bandwidth.
By using netfilter, PPS shaping is done on backend level, once packet
has left the VM; which means after using an additional memory transaction
to copy packet from frontend. IMHO, at scale, shaping in this way should
save some memory transactions comparing to netfilter.
--=20
William

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