Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [PATCH 21/32] fs/aio: aio_wq isn't used in memory reclaim path | Date | Wed, 05 Jan 2011 10:49:19 -0500 |
| |
Benjamin LaHaise <bcrl@kvack.org> writes:
> On Wed, Jan 05, 2011 at 09:50:57AM -0500, Jeff Moyer wrote: >> > Yeap. Do you agree that the concurrency limit is necessary? If not, >> > we can just put everything onto system_wq. >> >> I'm not sure whether it's strictly necessary (there may very well be a >> need for this in the usb gadgetfs code), but keeping it the same at >> least seems safe. > > Limiting concurrency on aio requests is exactly the opposite of what the > usb gadgetfs requires.
I'll have to dig on what their requirements are. After briefly looking at mailing list archives, it appears they use the aio workqueue to queue work after a completed I/O. I think Zach actually had posted a patch to change them over to using their own workqueue for that. At any rate, it may well be that they don't have a concurrency requirement (in fact, it would be surprising if they did). However, I wasn't going to propose changing the way things were done w/o someone chiming in and saying they needed it.
> It's similarly bad for filesystem aio when there's a mix of small and > large requests in flight.
Well, the aio workqueue isn't actually used by the filesystem aio paths at all (except for the fput_work, and that's being moved to the system workqueue).
Cheers, Jeff
| |