Message-ID: <4D8F2455.2080205@redhat.com>
Date: Sun, 27 Mar 2011 13:49:41 +0200
From: Avi Kivity <avi@redhat.com>
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To: Jens Axboe <jaxboe@fusionio.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Chris Mason <chris.mason@oracle.com>
Subject: Re: [GIT PULL] Core block IO bits for 2.6.39
References: <4D8B4A89.80608@fusionio.com>
In-Reply-To: <4D8B4A89.80608@fusionio.com>
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On 03/24/2011 03:43 PM, Jens Axboe wrote:
> Hi Linus,
>
> This is the main pull request for the block IO layer and friends for
> 2.6.39.
>
> There are two major things in this tree:
>
> - The removal of the per-device plugging state for disks. On fast
>    devices, it ended up hammering the queue lock quite hard. The new
>    scheme puts the plugging state on the stack and allows an IO submitter
>    to finish his batch of IO before pushing it to the queue. Once that
>    push starts, we'll insert/merge with the existing queue.
>
>    A pointer to this plugging context is stored in the task structure. If
>    a task ends up blocking before it has submitted it's IO (usual cause
>    would be memory allocation of some sort), the plugged list is
>    auto-submitted before the task goes to sleep.

This is the fourth "do something if preempted" hook (the other three are 
kvm, cmwq, and perf).  Why not use sched notifiers for this?

-- 
error compiling committee.c: too many arguments to function

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