From: Cong Wang <amwang@redhat.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: David Miller <davem@davemloft.net>,
rick.jones2@hp.com, netdev@vger.kernel.org,
greearb@candelatech.com, eric.dumazet@gmail.com,
shemminger@vyatta.com, tgraf@redhat.com
Subject: RE: TCP delayed ACK heuristic
Date: Thu, 20 Dec 2012 20:41:10 +0800 [thread overview]
Message-ID: <1356007270.25310.20.camel@cr0> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B70FC@saturn3.aculab.com>
On Thu, 2012-12-20 at 09:57 +0000, David Laight wrote:
> > So, can we at least have a sysctl to control the timeout of the delayed
> > ACK? I mean the minimum 40ms. TCP_QUICKACK can help too, but it requires
> > the receiver to modify the application and has to be set every time when
> > calling recv().
>
> A sysctl in inappropriate - it affects the entire TCP protocol stack.
>
> You want different behaviour for different remote hosts (probably
> different subnets).
> In particular your local subnet is unlikely to have packet loss
> and very likely to have a very low RTT.
>
> AFAICT a lot of the recent 'tuning' has been done for web/ftp
> servers that are very remote from the client. These connections
> are also request-response ones - quite often with large responses.
>
> IMHO This has been to the detriment of local connections.
>
A customer prefers faster response in their low-loss environment, 40ms
is not good. Of course, they are supposed to know their environment when
they tune this.
Or maybe a sysctl equals to TCP_QUICKACK?
next prev parent reply other threads:[~2012-12-20 12:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <270756364.27707018.1355842632348.JavaMail.root@redhat.com>
2012-12-18 15:11 ` TCP delayed ACK heuristic Cong Wang
2012-12-18 16:30 ` Eric Dumazet
2012-12-19 6:54 ` Cong Wang
2012-12-18 16:39 ` David Laight
2012-12-18 17:54 ` Rick Jones
2012-12-19 9:52 ` David Laight
2012-12-19 7:00 ` Cong Wang
2012-12-19 18:39 ` Rick Jones
2012-12-19 20:59 ` David Miller
2012-12-20 3:23 ` Cong Wang
2012-12-20 9:57 ` David Laight
2012-12-20 12:41 ` Cong Wang [this message]
2012-12-19 23:08 ` Eric Dumazet
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