Date: Tue, 25 Nov 2008 15:59:49 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: suparna@in.ibm.com, Zach Brown <zach.brown@oracle.com>,
       linux-aio@kvack.org, Jeff Moyer <jmoyer@redhat.com>,
       Anthony Liguori <aliguori@us.ibm.com>, linux-kernel@vger.kernel.org,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: kvm aio wishlist
Message-ID: <20081125145949.GD14147@elte.hu>
References: <492B0CDD.7080000@redhat.com> <492B2348.9090008@oracle.com> <492B2976.3010209@redhat.com> <492B3912.3030707@oracle.com> <492BC5CB.6000609@redhat.com> <20081125101923.GA28123@in.ibm.com> <492BD807.4000002@redhat.com>
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* Avi Kivity <avi@redhat.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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