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From: Eric Dumazet <eric.dumazet@gmail.com>
To: monstr@monstr.eu
Cc: David Miller <davem@davemloft.net>,
	netdev@vger.kernel.org, hadi@cyberus.ca, therbert@google.com,
	microblaze-uclinux@itee.uq.edu.au
Subject: Re: [PATCH net-next-2.6] net: Increase NET_SKB_PAD to 64 bytes
Date: Fri, 07 May 2010 11:55:14 +0200	[thread overview]
Message-ID: <1273226114.2261.42.camel@edumazet-laptop> (raw)
In-Reply-To: <4BE3E1D6.30907@monstr.eu>

Le vendredi 07 mai 2010 à 11:48 +0200, Michal Simek a écrit :
> David Miller wrote:
> > From: Michal Simek <monstr@monstr.eu>
> > Date: Fri, 07 May 2010 09:53:48 +0200
> > 
> >> I will add this Microblaze patch to my repo for testing and anyway
> >> should go through my repo.
> > 
> > It's already in the net-next-2.6 tree.
> 
> Anyway.
> 
> I am ok with removing NET_IP_ALIGN because it is already defined in 
> skbuff.h to 2.
> But increasing NET_SKB_PAD to 64 caused that Microblaze extends skb 
> buffers for some bytes.
> I measured it by iperf and netperf and I see regression around 1-2Mbit/s 
> that's why I would like to ask you to revert this patch or keep at least 
> NET_SKB_PAD part.

Interesting.

Increasing NET_SKB_PAD to say 128 or 256 should not have performance
impact, but reserve a bit more ram. (truesize...)

Investigation is needed. Maybe your NIC now allocates high order pages ?

What driver are you using ?



  reply	other threads:[~2010-05-07  9:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-05  5:24 [PATCH net-next-2.6] net: Increase NET_SKB_PAD to 64 bytes Eric Dumazet
2010-05-07  5:02 ` David Miller
2010-05-07  5:15   ` Eric Dumazet
2010-05-07  5:28     ` [microblaze-uclinux] " John Williams
2010-05-07  6:29       ` David Miller
2010-05-07  7:53     ` Michal Simek
2010-05-07  8:32       ` David Miller
2010-05-07  9:02         ` Michal Simek
2010-05-07  9:48         ` Michal Simek
2010-05-07  9:55           ` Eric Dumazet [this message]
2010-05-07 10:09             ` Michal Simek
2010-05-07 10:27               ` Eric Dumazet
2010-05-07  9:56           ` David Miller

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