On 15/07/2020 11:49, Pavel Begunkov wrote: > 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? I think, if you're going to push this idea, we should start a new thread CC'ing strace devs. -- Pavel Begunkov
