netdev - Re: OFT - reserving CPU's for networking

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Message-ID: <Pine.LNX.4.62.1005012222320.24624@wlug.westbo.se>
Date:	Sat, 1 May 2010 22:31:05 +0200 (CEST)
From:	Martin Josefsson <gandalf@...fs.se>
To:	David Miller <davem@...emloft.net>
cc:	tglx@...utronix.de, shemminger@...tta.com, eric.dumazet@...il.com,
	ak@...goyle.fritz.box, netdev@...r.kernel.org, andi@...stfloor.org,
	peterz@...radead.org
Subject: Re: OFT - reserving CPU's for networking

On Fri, 30 Apr 2010, David Miller wrote:

> Then we can do cool tricks like having the cpu spin on a mwait() on the
> network device's status descriptor in memory.

Can you have mwait monitor multiple cachelines for stores? If not then it 
might be hard to do that when you have multiple nics and you actually 
need to use the status descriptors, otherwise you could possibly have them 
all written to the same cacheline. 
Or if the nic doesn't support updating a status descriptor in memory.

If you just want to wake up quickly without using interrupts it might be 
possible to abuse MSI to wake up without actually using interrupts, set 
the address to the cacheline that is being monitored.

/Martin
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