On 15/07/2020 11:41, Miklos Szeredi wrote: > On Wed, Jul 15, 2020 at 10:33 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: >> >> On 14/07/2020 14:55, Miklos Szeredi wrote: >>> On Tue, Jul 14, 2020 at 1:36 PM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: >>>> >>>> On 14/07/2020 11:07, Miklos Szeredi wrote: >>>>> On Tue, Jul 14, 2020 at 8:51 AM Pavel Machek <pavel@xxxxxxx> wrote: >>>>>> >>>>>> Hi! >>>>>> >>>>>>>> At first, I thought that the proposed system call is capable of >>>>>>>> reading *multiple* small files using a single system call - which >>>>>>>> would help increase HDD/SSD queue utilization and increase IOPS (I/O >>>>>>>> operations per second) - but that isn't the case and the proposed >>>>>>>> system call can read just a single file. >>>>>>> >>>>>>> If you want to do this for multple files, use io_ring, that's what it >>>>>>> was designed for. I think Jens was going to be adding support for the >>>>>>> open/read/close pattern to it as well, after some other more pressing >>>>>>> features/fixes were finished. >>>>>> >>>>>> What about... just using io_uring for single file, too? I'm pretty >>>>>> sure it can be wrapped in a library that is simple to use, avoiding >>>>>> need for new syscall. >>>>> >>>>> Just wondering: is there a plan to add strace support to io_uring? >>>>> And I don't just mean the syscalls associated with io_uring, but >>>>> tracing the ring itself. >>>> >>>> What kind of support do you mean? io_uring is asynchronous in nature >>>> with all intrinsic tracing/debugging/etc. problems of such APIs. >>>> And there are a lot of handy trace points, are those not enough? >>>> >>>> Though, this can be an interesting project to rethink how async >>>> APIs are worked with. >>> >>> Yeah, it's an interesting problem. The uring has the same events, as >>> far as I understand, that are recorded in a multithreaded strace >>> output (syscall entry, syscall exit); nothing more is needed> >>> I do think this needs to be integrated into strace(1), otherwise the >>> usefulness of that tool (which I think is *very* high) would go down >>> drastically as io_uring usage goes up. >> >> Not touching the topic of usefulness of strace + io_uring, but I'd rather >> have a tool that solves a problem, than a problem that created and honed >> for a tool. > > Sorry, I'm not getting the metaphor. Can you please elaborate? Sure, I mean _if_ there are tools that conceptually suit better, I'd prefer to work with them, then trying to shove a new and possibly alien infrastructure into strace. But my knowledge of strace is very limited, so can't tell whether that's the case. E.g. can it utilise static trace points? -- Pavel Begunkov
