From: Anton Blanchard <anton@samba•org>
To: Michael Chan <mchan@broadcom•com>
Cc: Matthew Carlson <mcarlson@broadcom•com>,
"davem@davemloft•net" <davem@davemloft•net>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"andy@greyhouse•net" <andy@greyhouse•net>
Subject: Re: [PATCH net-next 09/14] tg3: Improve small packet performance
Date: Thu, 5 Aug 2010 09:08:25 +1000 [thread overview]
Message-ID: <20100804230825.GQ29316@kryten> (raw)
In-Reply-To: <1280962049.7554.25.camel@HP1>
Hi,
> We generally only get an estimate of the available tx ring size when we
> call tg3_tx_avail(), so memory barriers are not generally needed. We
> put a compiler barrier there to make sure that the compiler will fetch
> the tx_prod and tx_cons from memory to give us a better estimate.
>
> In specific cases detailed in the patch description, we do need memory
> barriers when we call netif_tx_stop_queue() and then check for the tx
> ring. We decided to put memory barriers exactly where they're needed
> instead of inside tg3_tx_avail() which is an overkill.
Thanks Matt and Michael. I was pretty sure you were thinking about
ordering issues but wanted to double check.
Anton
prev parent reply other threads:[~2010-08-04 23:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-02 21:26 [PATCH net-next 09/14] tg3: Improve small packet performance Matt Carlson
2010-08-04 22:27 ` Anton Blanchard
2010-08-04 22:46 ` Matt Carlson
2010-08-04 22:47 ` Michael Chan
2010-08-04 23:08 ` Anton Blanchard [this message]
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