netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Alexander Duyck <alexander.h.duyck@intel.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Kieran Mansley <kmansley@solarflare.com>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Ben Hutchings <bhutchings@solarflare.com>,
	netdev@vger.kernel.org
Subject: Re: TCPBacklogDrops during aggressive bursts of traffic
Date: Wed, 23 May 2012 10:10:36 -0700	[thread overview]
Message-ID: <4FBD1A0C.4070606@intel.com> (raw)
In-Reply-To: <1337791189.3361.3029.camel@edumazet-glaptop>

On 05/23/2012 09:39 AM, Eric Dumazet wrote:
> On Wed, 2012-05-23 at 18:12 +0200, Eric Dumazet wrote:
>
>> With current driver, a MTU=1500 frame uses :
>>
>> sk_buff (256 bytes)
>> skb->head : 1024 bytes  (or more exaclty now : 512 + 384)
> By the way, NET_SKB_PAD adds 64 bytes so its 64 + 512 + 384 = 960
Actually pahole seems to be indicating to me the size of skb_shared_info
is 320, unless something has changed in the last few days.

When I get a chance I will try to remember to reduce the ixgbe header
size to 256 which should also help.  The only reason it is set to 512
was to deal with the fact that the old alloc_skb code wasn't aligning
the shared info with the end of whatever size was allocated and so the
512 was an approximation to make better use of the 1K slab allocation
back when we still were using hardware packet split.  That should help
to improve the page utilization for the headers since that would
increase the uses of a page from 4 to 6 for the skb head frag, and it
would drop truesize by another 256 bytes.

Thanks,

Alex

  reply	other threads:[~2012-05-23 17:10 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-15 14:38 TCPBacklogDrops during aggressive bursts of traffic Kieran Mansley
2012-05-15 14:56 ` Eric Dumazet
2012-05-15 15:00   ` Eric Dumazet
2012-05-15 16:29   ` Kieran Mansley
2012-05-15 16:34     ` Eric Dumazet
2012-05-15 16:47       ` Ben Hutchings
2012-05-15 17:01         ` Eric Dumazet
2012-05-15 17:23           ` Eric Dumazet
2012-05-17 16:31           ` Kieran Mansley
2012-05-17 16:37             ` Eric Dumazet
2012-05-18 15:45               ` Kieran Mansley
2012-05-18 15:49                 ` Eric Dumazet
2012-05-18 15:53                   ` Kieran Mansley
2012-05-18 18:40                 ` Eric Dumazet
2012-05-22  8:20               ` Kieran Mansley
2012-05-22  9:25                 ` Eric Dumazet
2012-05-22  9:30                   ` Eric Dumazet
2012-05-22 15:09                     ` Kieran Mansley
2012-05-22 16:12                       ` Eric Dumazet
2012-05-22 16:32                         ` Kieran Mansley
2012-05-22 16:45                           ` Eric Dumazet
2012-05-22 20:54                             ` Eric Dumazet
2012-05-23  9:44                               ` Eric Dumazet
2012-05-23 12:09                                 ` Eric Dumazet
2012-05-23 16:04                                   ` Alexander Duyck
2012-05-23 16:12                                     ` Eric Dumazet
2012-05-23 16:39                                       ` Eric Dumazet
2012-05-23 17:10                                         ` Alexander Duyck [this message]
2012-05-23 21:19                                           ` Alexander Duyck
2012-05-23 21:37                                             ` Eric Dumazet
2012-05-23 22:03                                               ` Alexander Duyck
2012-05-23 16:58                                       ` Alexander Duyck
2012-05-23 17:24                                         ` Eric Dumazet
2012-05-23 17:57                                           ` Alexander Duyck
2012-05-23 17:34                                 ` David Miller
2012-05-23 17:46                                   ` Eric Dumazet
2012-05-23 17:57                                     ` David Miller

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4FBD1A0C.4070606@intel.com \
    --to=alexander.h.duyck@intel.com \
    --cc=bhutchings@solarflare.com \
    --cc=eric.dumazet@gmail.com \
    --cc=jeffrey.t.kirsher@intel.com \
    --cc=kmansley@solarflare.com \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).