Messages in this thread | | | Date | Wed, 5 Jan 2011 03:28:02 -0800 | From | Tejun Heo <> | Subject | Re: [PATCH 21/32] fs/aio: aio_wq isn't used in memory reclaim path |
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Hello,
On Tue, Jan 04, 2011 at 10:56:20AM -0500, Jeff Moyer wrote: > > aio_wq isn't used during memory reclaim. Convert to alloc_workqueue() > > without WQ_MEM_RECLAIM. It's possible to use system_wq but given that > > the number of work items is determined from userland and the work item > > may block, enforcing strict concurrency limit would be a good idea. > > I would think that just given that it may block would be enough to keep > it off of the system workqueue.
Oh, workqueue now can handle parallel execution. Blocking on system workqueue is no longer a problem. One of the main reasons for this whole series.
> > @@ -85,7 +85,7 @@ static int __init aio_setup(void) > > kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); > > kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); > > > > - aio_wq = create_workqueue("aio"); > > + aio_wq = alloc_workqueue("aio", 0, 1); /* used to limit concurrency */ > > OK, the only difference here is the removal of the WQ_MEM_RECLAIM flag, > as you noted.
Yeap. Do you agree that the concurrency limit is necessary? If not, we can just put everything onto system_wq.
> > @@ -569,7 +569,7 @@ static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) > > spin_lock(&fput_lock); > > list_add(&req->ki_list, &fput_head); > > spin_unlock(&fput_lock); > > - queue_work(aio_wq, &fput_work); > > + schedule_work(&fput_work); > > I'm not sure where this change fits into the patch description. Why did > you do this?
Yeah, that's me being forgetful. Now that aio_wq is solely used to throttle the max concurrency of aio work items, I thought it would be better to push fput_work to system workqueue so that it doesn't interact with aio work items. I'll update the patch description.
Thanks.
-- tejun
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