Re: RFC: Nagle latency tuning

!MAILaRCHIVE_VOTE_RePLACE
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To: Chris Snook <csnook@...>
Cc: Andi Kleen <andi@...>, David Miller <davem@...>, <netdev@...>
Date: Monday, September 22, 2008 - 6:47 pm

> Indeed.  Setting tcp_delack_min to 0 completely eliminated the undesired 

What did it do to the packets per second or per unit of work?  Depending 
on the nature of the race between the ACK returning from the remote and 
the application pushing more bytes into the socket, I'd think that 
setting the delayed ack timer to zero could result in more traffic on 
the network (those bare ACKs) than simply setting TCP_NODELAY at the source.

And since with small packets and/or copy avoidance an ACK is 
(handwaving) just as many CPU cycles at either end as a data segment 
that also means a bump in CPU utilization.

rick jones
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Messages in current thread:
RFC: Nagle latency tuning, Christopher Snook, (Mon Sep 8, 5:56 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 8, 6:55 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 1:22 am)
Re: RFC: Nagle latency tuning, Rick Jones, (Mon Sep 8, 6:39 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 1:10 am)
Re: RFC: Nagle latency tuning, Rick Jones, (Tue Sep 9, 12:33 pm)
Re: RFC: Nagle latency tuning, Chuck Lever, (Tue Sep 9, 12:54 pm)
Re: RFC: Nagle latency tuning, Rick Jones, (Tue Sep 9, 1:54 pm)
Re: RFC: Nagle latency tuning, Arnaldo Carvalho de Melo, (Tue Sep 9, 1:21 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Tue Sep 9, 10:36 am)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 2:40 pm)
Re: RFC: Nagle latency tuning, David Miller, (Tue Sep 9, 3:59 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 6:49 am)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 7:09 am)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 4:30 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Mon Sep 22, 6:22 pm)
Re: RFC: Nagle latency tuning, Rick Jones, (Mon Sep 22, 6:47 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Mon Sep 22, 6:57 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 6:26 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Mon Sep 22, 7:00 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 7:13 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 7:24 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 7:21 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 8:14 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 9:40 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 10:23 pm)
Re: RFC: Nagle latency tuning, David Miller, (Mon Sep 22, 10:28 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 10:41 pm)
Re: RFC: Nagle latency tuning, Rick Jones, (Mon Sep 22, 8:33 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Mon Sep 22, 10:12 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 4:25 pm)
Re: RFC: Nagle latency tuning, Andi Kleen, (Tue Sep 9, 3:07 pm)
Re: RFC: Nagle latency tuning, Chris Snook, (Thu Sep 11, 12:08 am)
Re: RFC: Nagle latency tuning, Arnaldo Carvalho de Melo, (Tue Sep 9, 3:21 pm)
Re: RFC: Nagle latency tuning, David Miller, (Tue Sep 9, 1:17 am)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 1:56 am)
Re: RFC: Nagle latency tuning, Evgeniy Polyakov, (Tue Sep 9, 2:22 am)
Re: RFC: Nagle latency tuning, Arnaldo Carvalho de Melo, (Tue Sep 9, 9:00 am)
Re: RFC: Nagle latency tuning, Chris Snook, (Tue Sep 9, 2:28 am)
Re: RFC: Nagle latency tuning, David Miller, (Tue Sep 9, 2:02 am)
Re: RFC: Nagle latency tuning, Mark Brown, (Tue Sep 9, 6:31 am)
Re: RFC: Nagle latency tuning, David Miller, (Tue Sep 9, 8:05 am)
Re: RFC: Nagle latency tuning, Mark Brown, (Tue Sep 9, 8:09 am)
Re: RFC: Nagle latency tuning, David Miller, (Tue Sep 9, 8:19 am)