From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dave Taht <dave.taht@gmail.com>
Cc: Keith Winstein <keithw@mit.edu>,
"codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>
Subject: Re: [Codel] sprout
Date: Wed, 10 Jul 2013 16:07:18 -0700 [thread overview]
Message-ID: <1373497638.4600.24.camel@edumazet-glaptop> (raw)
In-Reply-To: <CAA93jw4JPqoTfNOzTRCKu_DJUMJsHzGZVe_GAaCq3hNYyTyOZw@mail.gmail.com>
On Wed, 2013-07-10 at 15:44 -0700, Dave Taht wrote:
> I'd made a suggestion elsewhere that TSQ migrate down in size from 128k to
> lower as the number of active flows increased. Something like
> tcp_limit_output_size = max((2*BQL's limit)/(number of flows),mtu)
>
> but I realize now that tcp has no idea what interface it's going out
> at any given
> time... still I'm on a quest to minimize latency and let offloads still work..
At Google we tried to plug something at the time TX completion happens
(tcp_wfree())
The more time skb are waiting on qdisc, the less tcp_limit_output_size
should be for the TCP flow.
But tcp_limit_output_size had to be per socket tunable instead of
global. Experiments showed no real improvement over existing TCP
behavior.
The tcp_tso_should_defer() was kind of fixed lately [1] anyway, and we
plan to upstream another patch in this function to better preserve ACK
clocking.
[1] :
http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=f4541d60a449afd40448b06496dcd510f505928e
next prev parent reply other threads:[~2013-07-10 23:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-10 19:30 Dave Taht
2013-07-10 20:19 ` Keith Winstein
2013-07-10 20:38 ` Jim Gettys
2013-07-10 20:41 ` Keith Winstein
2013-07-10 20:46 ` Jim Gettys
2013-07-10 21:42 ` Dave Taht
2013-07-10 22:10 ` Kathleen Nichols
2013-07-10 22:44 ` Dave Taht
2013-07-10 23:07 ` Eric Dumazet [this message]
2013-07-11 15:45 ` Kathleen Nichols
2013-07-11 16:22 ` Eric Dumazet
2013-07-11 16:54 ` Kathleen Nichols
2013-07-11 17:17 ` Dave Taht
2013-07-10 20:40 ` Dave Taht
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