Date: Tue, 07 Jan 2014 16:20:53 -0500 (EST)
Message-Id: <20140107.162053.1127386147694253061.davem@davemloft.net>
To: bpoirier@suse.de
Cc: edumazet@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        therbert@google.com
Subject: Re: [PATCH v2] net: Do not enable tx-nocache-copy by default
From: David Miller <davem@davemloft.net>
In-Reply-To: <1389107470-18213-1-git-send-email-bpoirier@suse.de>
References: <20140106.200002.1747627391067832069.davem@davemloft.net>
	<1389107470-18213-1-git-send-email-bpoirier@suse.de>
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From: Benjamin Poirier <bpoirier@suse.de>
Date: Tue,  7 Jan 2014 10:11:10 -0500

> There are many cases where this feature does not improve performance or even
> reduces it.
> 
> For example, here are the results from tests that I've run using 3.12.6 on one
> Intel Xeon W3565 and one i7 920 connected by ixgbe adapters. The results are
> from the Xeon, but they're similar on the i7. All numbers report the
> mean?stddev over 10 runs of 10s.
> 
> 1) latency tests similar to what is described in "c6e1a0d net: Allow no-cache
> copy from user on transmit"
> There is no statistically significant difference between tx-nocache-copy
> on/off.
> nic irqs spread out (one queue per cpu)
 ...
> CC: Tom Herbert <therbert@google.com>
> Signed-off-by: Benjamin Poirier <bpoirier@suse.de>

Looks good, applied, thanks.
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