From: David Miller <davem@davemloft.net>
To: rcj@linux.vnet.ibm.com
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] ibmveth: Increase default copybreak limits to 2k
Date: Thu, 21 Oct 2010 07:45:25 -0700 (PDT) [thread overview]
Message-ID: <20101021.074525.71113963.davem@davemloft.net> (raw)
In-Reply-To: <20101021143753.GA5567@linux.vnet.ibm.com>
From: Robert Jennings <rcj@linux.vnet.ibm.com>
Date: Thu, 21 Oct 2010 09:37:53 -0500
> Increase the copybreak limits for rx and tx from 128 bytes
> to 2048 bytes. These limits were added by commits
> 8d86c61ae41d9068fd5e5cc01a4abd53c4fe3ab5 and
> c08cc3ccebd46dce44d13a8ce81d249e687eeb8a to make use of a
> bounce buffer for packets below 128 bytes. This avoids
> tearing down and creating a TCE entry.
>
> Performance testing shows that this default limit can be
> increased from 128 to 2048 for both rx and tx copybreak.
> This resulted in ~10% throughput increase for for packets
> that fit this limit without affecting performance for larger
> packets.
>
> Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
For a default MTU of 1500 this means the copybreak will
never be used.
This makes absolutely no sense, are you doing these tests
with Jumbo frames?
next prev parent reply other threads:[~2010-10-21 14:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-21 14:37 [PATCH] ibmveth: Increase default copybreak limits to 2k Robert Jennings
2010-10-21 14:45 ` David Miller [this message]
2010-10-21 15:17 ` Robert Jennings
2010-10-24 22:40 ` David Miller
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