From: Ben Hutchings <bhutchings@solarflare.com>
To: Anton Blanchard <anton@samba.org>
Cc: leitao@linux.vnet.ibm.com, michael@ellerman.id.au,
jesse@kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 07/15] ehea: Allocate large enough skbs to avoid partial cacheline DMA writes
Date: Thu, 12 May 2011 03:52:48 +0100 [thread overview]
Message-ID: <1305168768.4065.382.camel@localhost> (raw)
In-Reply-To: <20110512005623.100278010@samba.org>
On Thu, 2011-05-12 at 10:52 +1000, Anton Blanchard wrote:
> plain text document attachment (ehea_8.patch)
> The ehea adapter has a mode where it will avoid partial cacheline DMA
> writes on receive by always padding packets to fall on a cacheline
> boundary.
>
> Unfortunately we currently aren't allocating enough space for a full
> ethernet MTU packet to be rounded up, so this optimisation doesn't hit.
>
> It's unfortunate that the next largest packet size exposed by the
> hypervisor interface is 2kB, meaning our skb allocation comes out of a
> 4kB SLAB. However the performance increase due to this optimisation is
> quite large and my TCP stream numbers increase from 900MB to 1000MB/sec.
You can allocate page buffers and then split them into exactly 2K
segments. If you switch from inet_lro to GRO then GRO will handle the
eventual skb allocation for you (even for non-mergeable packets).
Ben.
--
Ben Hutchings, Senior Software 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:[~2011-05-12 2:52 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-12 0:52 [PATCH 00/15] ehea updates v2 Anton Blanchard
2011-05-12 0:52 ` [PATCH 01/15] ehea: Remove NETIF_F_LLTX Anton Blanchard
2011-05-12 0:52 ` [PATCH 02/15] ehea: Update multiqueue support Anton Blanchard
2011-05-12 2:31 ` Joe Perches
2011-05-12 2:57 ` Ben Hutchings
2011-05-12 0:52 ` [PATCH 03/15] ehea: Remove force_irq logic in napi poll routine Anton Blanchard
2011-05-12 2:31 ` Joe Perches
2011-05-12 3:06 ` David Miller
2011-05-12 2:47 ` Ben Hutchings
2011-05-24 3:32 ` Benjamin Herrenschmidt
2011-05-12 0:52 ` [PATCH 04/15] ehea: Remove num_tx_qps module option Anton Blanchard
2011-05-12 0:52 ` [PATCH 05/15] ehea: Dont check NETIF_F_TSO in TX path Anton Blanchard
2011-05-12 0:52 ` [PATCH 06/15] ehea: Add vlan_features Anton Blanchard
2011-05-12 0:52 ` [PATCH 07/15] ehea: Allocate large enough skbs to avoid partial cacheline DMA writes Anton Blanchard
2011-05-12 2:52 ` Ben Hutchings [this message]
2011-05-12 0:52 ` [PATCH 08/15] ehea: Simplify ehea_xmit2 and ehea_xmit3 Anton Blanchard
2011-05-12 0:52 ` [PATCH 09/15] ehea: Merge swqe2 TSO and non TSO paths Anton Blanchard
2011-05-12 0:52 ` [PATCH 10/15] ehea: Simplify type 3 transmit routine Anton Blanchard
2011-05-12 0:52 ` [PATCH 11/15] ehea: Remove some unused definitions Anton Blanchard
2011-05-12 0:52 ` [PATCH 12/15] ehea: Add 64bit statistics Anton Blanchard
2011-05-12 0:52 ` [PATCH 13/15] ehea: Remove LRO support Anton Blanchard
2011-05-12 0:52 ` [PATCH 14/15] ehea: Add GRO support Anton Blanchard
2011-05-12 6:03 ` Michał Mirosław
2011-05-12 0:52 ` [PATCH 15/15] ehea: Remove unused tcp_end field in send WQ Anton Blanchard
2011-05-12 2:31 ` Joe Perches
2011-05-12 3:06 ` David Miller
2011-05-12 3:12 ` Joe Perches
2011-05-31 1:16 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2011-10-14 15:30 EHEA updates Thadeu Lima de Souza Cascardo
2011-10-14 15:31 ` [PATCH 07/15] ehea: Allocate large enough skbs to avoid partial cacheline DMA writes Thadeu Lima de Souza Cascardo
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