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From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Cc: "Neal Cardwell" <ncardwell@google.com>,
	"David Miller" <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	"Tom Herbert" <therbert@google.com>,
	"Maciej Żenczykowski" <maze@google.com>,
	"Yuchung Cheng" <ycheng@google.com>
Subject: Re: [PATCH v2 net-next] tcp: avoid expensive pskb_expand_head() calls
Date: Thu, 19 Apr 2012 16:10:52 +0200	[thread overview]
Message-ID: <1334844652.2395.187.camel@edumazet-glaptop> (raw)
In-Reply-To: <1334843527.2395.182.camel@edumazet-glaptop>

On Thu, 2012-04-19 at 15:52 +0200, Eric Dumazet wrote:

> And disabling GRO on receiver definitely demonstrates the problem, even
> with a single flow. (and performance drops from 9410 Mbit to 6050 Mbit)

That insane. 

Performance drops so much because we _drop_ incoming ACKS :

<     TCPSackShifted: 39117
<     TCPSackMerged: 16500
<     TCPSackShiftFallback: 5092
<     TCPBacklogDrop: 27965
---
>     TCPSackShifted: 35122
>     TCPSackMerged: 16368
>     TCPSackShiftFallback: 4889
>     TCPBacklogDrop: 23247

Hmm, maybe we should reduce skb->truesize for small packets before
queueing them in socket backlog...

  reply	other threads:[~2012-04-19 14:10 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-17  9:06 [BUG] ixgbe: something wrong with queue selection ? Eric Dumazet
2012-04-17  9:16 ` Jeff Kirsher
2012-04-17 16:01   ` Alexander Duyck
2012-04-17 16:38     ` John Fastabend
2012-04-17 17:07       ` Ben Hutchings
2012-04-17 16:46     ` Eric Dumazet
2012-04-17 21:38       ` TSO not 10G friendly if peer is close enough Eric Dumazet
2012-04-17 21:47         ` David Miller
2012-04-18  3:00           ` Eric Dumazet
2012-04-18 15:49         ` [PATCH net-next] tcp: avoid expensive pskb_expand_head() calls Eric Dumazet
     [not found]           ` <4F8EF317.10504@hp.com>
2012-04-18 17:16             ` Eric Dumazet
2012-04-18 17:30               ` Rick Jones
2012-04-18 17:40                 ` Eric Dumazet
2012-04-18 18:40           ` Neal Cardwell
2012-04-18 19:18             ` Eric Dumazet
2012-04-18 19:51               ` [PATCH v2 " Eric Dumazet
2012-04-19 11:10                 ` Ilpo Järvinen
2012-04-19 11:30                   ` Eric Dumazet
2012-04-19 11:40                     ` Eric Dumazet
2012-04-19 11:57                       ` Ilpo Järvinen
2012-04-19 12:44                         ` Eric Dumazet
2012-04-20 12:27                           ` Ilpo Järvinen
2012-04-19 13:18                     ` Eric Dumazet
2012-04-19 13:52                       ` Eric Dumazet
2012-04-19 14:10                         ` Eric Dumazet [this message]
2012-04-19 17:20                           ` Rick Jones
2012-04-19 17:25                             ` Eric Dumazet
2012-04-19 17:48                               ` Rick Jones
2012-04-19 18:00                                 ` Eric Dumazet
2012-04-19 18:05                                   ` Rick Jones
2012-04-18 19:41           ` [PATCH " Vijay Subramanian
2012-04-18 19:49             ` Eric Dumazet

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