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From: Robert Watson <rwatson@FreeBSD.org>
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To: Sepherosa Ziehau <sepherosa@gmail.com>
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Cc: freebsd-net@freebsd.org, Ivan Voras <ivoras@freebsd.org>
Subject: Re: Advice on a multithreaded netisr patch?
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On Tue, 7 Apr 2009, Sepherosa Ziehau wrote:

>> This issue is almost entirely independent from things like the cache line 
>> miss issue, unless you hit the uncommon case of having to do work in 
>> m_pullup(), in which case life sucks.
>>
>> It would be useful to use DTrace to profile a number of the workfull 
>> m_foo() functions to make sure we're not hitting them in normal workloads, 
>> btw.
>
> I highly suspect m_pullup will take any real effect on RX path, given how 
> most of drivers allocate the mbuf for RX ring (all RX mbufs should be 
> mclusters).

Agreed, but it's good to be sure one is right about these things. :-)

Robert N M Watson
Computer Laboratory
University of Cambridge