On Thu, Mar 10, 2022 at 11:54 AM Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > On Sat, 5 Mar 2022 at 17:04, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > > > Show optional collected per-sb io stats in /proc/<pid>/mountstats > > for filesystems that do not implement their own show_stats() method > > and have generic per-sb stats enabled. > > I still think it's wrong to extend the /proc/*/mount* family of > interfaces. The big issue is that the kernel has to generate this > info for *all* mounts, even though the user may be just looking for > information on a specific mount. Your workaround is to enable the > info generation for only a subset of fs types, but this doesn't solve > the fundamental issue. > > So let's please implement a per-mount interface. Yes, it's a much > bigger project, but one which needs to be done at one point, and which > would be generally useful. There was tons of discussion around this > when dhowells tried to create one, and there was a suggestion by Linus > which I think all parties found acceptable: > > - return basic info in a binary format (similar to e.g. statx) > - after the fix binary structure allow misc info to be added using an > ascii format > > And since generating the info may be expensive in some cases, the > interface would need to allow selective queries (which statx does for > binary fields, but for ascii ones this is a new challenge). > > I think allowing the user to query the list of supported fields should > also be possible (again, statx supports this). > > So there are a number of requirements for this interface, and I'm not > quite sure what the best solution is. I can try to put something > together if there are no objections... No objections on my part. Feel free to use the iostat info as a case study for how common vfs info could be exported using this interface. Thanks, Amir.
