On 4/4/23 7:45?AM, Amir Goldstein wrote: > On Tue, Apr 4, 2023 at 12:21?PM Jan Kara <jack@xxxxxxx> wrote: >> >> On Mon 03-04-23 11:23:25, Jens Axboe wrote: >>> On 4/3/23 11:15?AM, Amir Goldstein wrote: >>>>> On 4/3/23 11:00?AM, Amir Goldstein wrote: >>>>> io_uring does do it for non-polled IO, I don't think there's much point >>>>> in adding it to IOPOLL however. Not really seeing any use cases where >>>>> that would make sense. >>>>> >>>> >>>> Users subscribe to fsnotify because they want to be notified of changes/ >>>> access to a file. >>>> Why do you think that polled IO should be exempt? >>> >>> Because it's a drastically different use case. If you're doing high >>> performance polled IO, then you'd never rely on something as slow as >>> fsnotify to tell you of any changes that happened to a device or file. >>> That would be counter productive. >> >> Well, I guess Amir wanted to say that the application using fsnotify is not >> necessarily the one doing high performance polled IO. You could have e.g. >> data mirroring application A tracking files that need mirroring to another >> host using fsnotify and if some application B uses high performance polled >> IO to modify a file, application A could miss the modified file. >> >> That being said if I look at exact details, currently I don't see a very >> realistic usecase that would have problems (people don't depend on >> FS_MODIFY or FS_ACCESS events too much, usually they just use FS_OPEN / >> FS_CLOSE), which is likely why nobody reported these issues yet :). >> > > I guess so. > Our monitoring application also does not rely on FS_MODIFY/FS_ACCESS > as they could be too noisy. > > The thing that I find missing is being able to tell if a file was *actually* > accessed/modified in between open and close. > This information could be provided with FS_CLOSE event Agree, it's not a good fit for a lot of common use cases. -- Jens Axboe
