linux-kernel - Re: kvm aio wishlist

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Date:	Tue, 25 Nov 2008 15:59:49 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Avi Kivity <avi@...hat.com>
Cc:	suparna@...ibm.com, Zach Brown <zach.brown@...cle.com>,
	linux-aio@...ck.org, Jeff Moyer <jmoyer@...hat.com>,
	Anthony Liguori <aliguori@...ibm.com>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: kvm aio wishlist

* Avi Kivity <avi@...hat.com> wrote:

> Perhaps a variant of syslet, that is kernel-only, and does:
>
> - always allocate a new kernel stack at io_submit() time, but not a 
>   new thread

such a N:M threading design is a loss - sooner or later we arrive to a 
point where people actually start using it and then we want to 
load-balance and schedule these entities.

So i'd suggest the kthread based async engine i wrote for syslets. It 
worked well and for kernel-only entities it schedules super-fast - it 
can do up to 20 million events per second on a 16-way box i'm testing 
on. The objections about syslets were not related to the scheduling of 
it but were mostly about the userspace API/ABI: you dont have to use 
that.

	Ingo
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