From: Ben Hutchings <bhutchings@solarflare.com>
To: David Miller <davem@davemloft.net>
Cc: <yevgenyp@mellanox.co.il>, <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next 2/3] mlx4_en: moderate frequency of TX completions
Date: Thu, 23 Feb 2012 21:13:56 +0000 [thread overview]
Message-ID: <1330031636.2511.13.camel@bwh-desktop> (raw)
In-Reply-To: <20120223.144437.32389814881687535.davem@davemloft.net>
On Thu, 2012-02-23 at 14:44 -0500, David Miller wrote:
> From: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
> Date: Thu, 23 Feb 2012 15:34:27 +0200
>
> > No need to ask for completion for every packet being sent.
> > So the method is to ask for a completion every 16 packets,
> > or when the queue is about to be full.
> >
> > Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
>
> You absolutely cannot do this, you must signal completion and free up
> TX queue packets in a finite amount of time.
Really, sfc has been doing this forever.
Ben.
> This means that if you suddenly stop getting new packets to send
> you must still free up all the pending TX SKBs even if no more
> packets are given to the driver.
>
> Does your hardware unconditionally give a TX completion interrupt when
> the TX queue empties completely? If not, then you cannot make the
> change contained in this patch.
> --
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--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
next prev parent reply other threads:[~2012-02-23 21:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 13:34 [PATCH net-next 2/3] mlx4_en: moderate frequency of TX completions Yevgeny Petrilin
2012-02-23 19:44 ` David Miller
2012-02-23 21:13 ` Ben Hutchings [this message]
2012-02-23 21:26 ` Ben Hutchings
2012-02-23 21:47 ` David Miller
2012-02-23 21:46 ` David Miller
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