From: David Miller <davem@davemloft.net>
To: andi@firstfloor.org
Cc: jheffner@psc.edu, ilpo.jarvinen@helsinki.fi,
lachlan.andrew@gmail.com, netdev@vger.kernel.org,
quetchen@caltech.edu
Subject: Re: SACK scoreboard
Date: Tue, 08 Jan 2008 22:39:25 -0800 (PST) [thread overview]
Message-ID: <20080108.223925.105105455.davem@davemloft.net> (raw)
In-Reply-To: <p73sl17pwfy.fsf@bingen.suse.de>
From: Andi Kleen <andi@firstfloor.org>
Date: Wed, 09 Jan 2008 03:25:05 +0100
> David Miller <davem@davemloft.net> writes:
> >
> > The big problem is that recovery from even a single packet loss in a
> > window makes us run kfree_skb() for a all the packets in a full
> > window's worth of data when recovery completes.
>
> Why exactly is it a problem to free them all at once? Are you worried
> about kernel preemption latencies?
If the cpu is there spinning freeing up 500,000 SKBs, it isn't
processing RX packets.
It adds severe spikes in CPU utilization that are even moderate
line rates begins to affect RTTs.
Or do you think it's OK to process 500,000 SKBs while locked
in a software interrupt.
Perhaps you have another broken awk script to prove this :-)
next prev parent reply other threads:[~2008-01-09 6:39 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <aa7d2c6d0711261023m3d2dd850o76a8f44aef022f39@mail.gmail.com>
[not found] ` <001001c83063$9adbc9d0$d5897e82@csp.uiuc.edu>
2007-11-28 23:47 ` [PATCH] tcp-illinois: incorrect beta usage Stephen Hemminger
2007-11-29 0:25 ` Lachlan Andrew
2007-11-29 0:43 ` Stephen Hemminger
2007-11-29 5:26 ` Shao Liu
2007-12-03 22:52 ` [RFC] TCP illinois max rtt aging Stephen Hemminger
2007-12-03 23:06 ` Lachlan Andrew
2007-12-03 23:59 ` Shao Liu
2007-12-04 0:32 ` Stephen Hemminger
2007-12-04 1:23 ` Lachlan Andrew
2007-12-04 8:37 ` Ilpo Järvinen
2007-12-07 3:27 ` Lachlan Andrew
2007-12-07 11:05 ` Ilpo Järvinen
2007-12-07 12:41 ` David Miller
2007-12-07 13:05 ` Ilpo Järvinen
2007-12-07 18:27 ` Ilpo Järvinen
2007-12-08 1:32 ` David Miller
2007-12-11 11:59 ` [RFC PATCH net-2.6.25 uncompilable] [TCP]: Avoid breaking GSOed skbs when SACKed one-by-one (Was: Re: [RFC] TCP illinois max rtt aging) Ilpo Järvinen
2007-12-11 12:32 ` [RFC PATCH net-2.6.25 uncompilable] [TCP]: Avoid breaking GSOed skbs when SACKed one-by-one David Miller
2007-12-12 0:14 ` Lachlan Andrew
2007-12-12 15:11 ` David Miller
2007-12-12 23:35 ` Lachlan Andrew
2007-12-12 23:38 ` David Miller
2007-12-13 0:00 ` Stephen Hemminger
2007-12-15 9:51 ` SACK scoreboard (Was: Re: [RFC PATCH net-2.6.25 uncompilable] [TCP]: Avoid breaking GSOed skbs when SACKed one-by-one) Ilpo Järvinen
2008-01-08 7:36 ` SACK scoreboard David Miller
2008-01-08 12:12 ` Ilpo Järvinen
2008-01-09 7:58 ` David Miller
2008-01-08 16:51 ` John Heffner
2008-01-08 22:44 ` David Miller
2008-01-09 1:34 ` Lachlan Andrew
2008-01-09 6:35 ` David Miller
2008-01-09 2:25 ` Andi Kleen
2008-01-09 4:27 ` John Heffner
2008-01-09 6:41 ` David Miller
2008-01-09 14:56 ` John Heffner
2008-01-09 18:14 ` SANGTAE HA
2008-01-09 18:23 ` John Heffner
2008-01-09 12:55 ` Ilpo Järvinen
2008-01-09 6:39 ` David Miller [this message]
2008-01-09 7:03 ` Andi Kleen
2008-01-09 7:16 ` David Miller
2008-01-09 9:47 ` Evgeniy Polyakov
2008-01-09 14:02 ` Andi Kleen
2007-11-29 14:12 ` [PATCH] tcp-illinois: incorrect beta usage Herbert Xu
2008-01-09 6:04 SACK scoreboard linux
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