Messages in this thread | | | Date | Wed, 3 Mar 2004 01:54:48 -0800 | From | Andrew Morton <> | Subject | Re: per-cpu blk_plug_list |
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Miquel van Smoorenburg <miquels@cistron.nl> wrote: > > According to Andrew Morton: > > And also having looked at Miquel's (currently slightly defective) > > implementation of the any_congested() API for devicemapper: > > > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.4-rc1/2.6.4-rc1-mm1/broken-out/queue-congestion-dm-implementation.patch > > > > I am thinking that an appropriate way of solving the blk_run_queues() lock > > contention problem is to nuke the global plug list altogther and make the > > unplug function a method in struct backing_device_info. > > > > This is conceptually the appropriate place to put it - it is almost always > > the case that when we run blk_run_queues() it is on behalf of an > > address_space, and the few remaining case can be simply deleted - > > mm/mempool.c is the last one I think. > > > > The implementation of backing_dev_info.unplug() would have to run the > > unplug_fn of every queue which contributes to the top-level queue (the > > thing which the address_space is sitting on top of). > > But then you need a pointer to the queue. In that case, > you might as well put the congested_fn pointer in the request_queue > too.
It already is. backing_dev_info is a member of struct request_queue.
> Then you get something like > https://www.redhat.com/archives/linux-lvm/2004-February/msg00203.html > (though I'd replace "rw" with "bdi_bits" like in the current patch).
Sure. This is all nice and simple stuff, except for the locking, which needs serious work.
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