Re: [GIT PULL] Queue free fix (was Re: [PATCH] block: Free queueresources at blk_release_queue())

From: Christoph Hellwig
Date: Wed Sep 28 2011 - 14:17:00 EST


On Wed, Sep 28, 2011 at 02:09:05PM -0400, Vivek Goyal wrote:
> I had thought of implementing a separate lock for throttling. Then I
> noticed few operations like checking for queue flags where I would
> be required to hold queue locks.

Can you do a writeup of these issues? E.g. if the flags are throtteling
specific we can move them to a separate flags field, if not we can
see if we can make them atomic or similar.

Right now on high iops device queue_lock is the major killer for
performance. It's one major reason (*) why a lot of the high iops devices
are all moving to ->make_request, which has other issues.

(*) others are struct request allocation and the pointless merge hash
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