Re: [PATCH 15/20] io-controller: map async requests to appropriatecgroup

From: Gui Jianfeng
Date: Sun Jun 21 2009 - 21:47:54 EST

Vivek Goyal wrote:
> o So far we were assuming that a bio/rq belongs to the task who is submitting
> it. It did not hold good in case of async writes. This patch makes use of
> blkio_cgroup pataches to attribute the aysnc writes to right group instead
> of task submitting the bio.
> o For sync requests, we continue to assume that io belongs to the task
> submitting it. Only in case of async requests, we make use of io tracking
> patches to track the owner cgroup.
> o So far cfq always caches the async queue pointer. With async requests now
> not necessarily being tied to submitting task io context, caching the
> pointer will not help for async queues. This patch introduces a new config
> option CONFIG_TRACK_ASYNC_CONTEXT. If this option is not set, cfq retains
> old behavior where async queue pointer is cached in task context. If it
> is not set, async queue pointer is not cached and we take help of bio

Here "If it is not set" should be "If it is set".

Gui Jianfeng

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