From: James Chapman <jchapman@katalix.com>
To: hadi@cyberus.ca
Cc: netdev@vger.kernel.org, davem@davemloft.net, jeff@garzik.org,
mandeep.baines@gmail.com, ossthema@de.ibm.com,
Stephen Hemminger <shemminger@osdl.org>
Subject: Re: RFC: possible NAPI improvements to reduce interrupt rates for low traffic rates
Date: Mon, 10 Sep 2007 10:20:15 +0100 [thread overview]
Message-ID: <46E50C4F.1070506@katalix.com> (raw)
In-Reply-To: <1189171370.4234.38.camel@localhost>
jamal wrote:
> If the problem i am trying to solve is "reduce cpu use at lower rate",
> then this is not the right answer because your cpu use has gone up.
The problem I'm trying to solve is "reduce the max interrupt rate from
NAPI drivers while minimizing latency". In modern systems, the interrupt
rate can be so high that the CPU spends too much time processing
interrupts, resulting in the system's behavior seen by the user being
degraded.
Having the poll() called when idle will always increase CPU usage. But
the feedback you and others are giving encourages me to find a better
compromise. At the end of the day, it's going to be a trade-off of cpu
and latency. The trade-off will be different for each hardware system
and application environment so parameters need to be tunable.
I'll go away and do some tests. I'll post results here for discussion later.
Thanks for your feedback.
--
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development
next prev parent reply other threads:[~2007-09-10 9:20 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-06 14:16 RFC: possible NAPI improvements to reduce interrupt rates for low traffic rates James Chapman
2007-09-06 14:37 ` Stephen Hemminger
2007-09-06 15:30 ` James Chapman
2007-09-06 15:37 ` Stephen Hemminger
2007-09-06 16:07 ` James Chapman
2007-09-06 23:06 ` jamal
2007-09-07 9:31 ` James Chapman
2007-09-07 13:22 ` jamal
2007-09-10 9:20 ` James Chapman [this message]
2007-09-10 12:27 ` jamal
2007-09-12 7:04 ` Bill Fink
2007-09-12 12:12 ` jamal
2007-09-12 13:50 ` James Chapman
2007-09-12 14:02 ` Stephen Hemminger
2007-09-12 16:26 ` James Chapman
2007-09-12 16:47 ` Mandeep Baines
2007-09-13 6:57 ` David Miller
2007-09-14 13:14 ` jamal
2007-09-07 21:20 ` Jason Lunz
2007-09-10 9:25 ` James Chapman
2007-09-07 3:55 ` Mandeep Singh Baines
2007-09-07 9:38 ` James Chapman
2007-09-08 16:42 ` Mandeep Singh Baines
2007-09-10 9:33 ` James Chapman
2007-09-10 12:12 ` jamal
2007-09-08 16:32 ` Andi Kleen
2007-09-10 9:25 ` James Chapman
2007-09-12 15:12 ` David Miller
2007-09-12 16:39 ` James Chapman
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