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From: Noah Goldstein <goldstein.w.n@gmail.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: "open list:IO_URING" <io-uring@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 8/8] io_uring: rearrange io_read()/write()
Date: Sat, 16 Oct 2021 20:35:11 -0500	[thread overview]
Message-ID: <CAFUsyfKbCbLL-yVPvf-QofauEzU91RuFGmhTUZ+nhe7aNXry0w@mail.gmail.com> (raw)
In-Reply-To: <869d5110-973b-6c70-604d-48d6108c0379@gmail.com>

On Sat, Oct 16, 2021 at 6:26 PM Pavel Begunkov <asml.silence@gmail.com> wrote:
>
> On 10/16/21 23:52, Noah Goldstein wrote:
> > On Thu, Oct 14, 2021 at 10:13 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
> >> -       /* If the file doesn't support async, just async punt */
> >> -       if (force_nonblock && !io_file_supports_nowait(req, WRITE))
> >> -               goto copy_iov;
> >> +               /* file path doesn't support NOWAIT for non-direct_IO */
> >> +               if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT) &&
> >
> > You can drop this 'force_nonblock' no?
>
> Indeed
>
> >
> >> +                   (req->flags & REQ_F_ISREG))
> >> +                       goto copy_iov;
> >>
> >> -       /* file path doesn't support NOWAIT for non-direct_IO */
> >> -       if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT) &&
> >> -           (req->flags & REQ_F_ISREG))
> >> -               goto copy_iov;
> >> +               kiocb->ki_flags |= IOCB_NOWAIT;
> >> +       } else {
> >> +               /* Ensure we clear previously set non-block flag */
> >> +               kiocb->ki_flags &= ~IOCB_NOWAIT;
> >> +       }
> >>
> >>          ret = rw_verify_area(WRITE, req->file, io_kiocb_ppos(kiocb), req->result);
> >>          if (unlikely(ret))
> >
> > ...
> >
> > What swapping order of conditions below:
> > if ((req->ctx->flags & IORING_SETUP_IOPOLL) && ret2 == -EAGAIN)
> >
> > The ret2 check will almost certainly be faster than 2x deref.
>
> Makes sense. Want to send a patch?
Done.
>
> --
> Pavel Begunkov

As an aside regarding the reorganization of io_write/io_read, maybe
it's worth it
to add seperate versions of the function for w/w.o force_nonblock?
Isn't something
that will change during the function and seems to really just be
adding 4-5 branches
(of runtime and code complexity) to each where factoring it would just
be +1 branch.

  reply	other threads:[~2021-10-17  1:35 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14 15:10 [PATCH for-next 0/8] read/write cleanup Pavel Begunkov
2021-10-14 15:10 ` [PATCH 1/8] io_uring: consistent typing for issue_flags Pavel Begunkov
2021-10-14 15:10 ` [PATCH 2/8] io_uring: prioritise read success path over fails Pavel Begunkov
2021-10-14 15:10 ` [PATCH 3/8] io_uring: optimise rw comletion handlers Pavel Begunkov
2021-10-14 15:10 ` [PATCH 4/8] io_uring: encapsulate rw state Pavel Begunkov
2021-10-18  6:06   ` Hao Xu
2021-10-14 15:10 ` [PATCH 5/8] io_uring: optimise read/write iov state storing Pavel Begunkov
2021-10-14 15:10 ` [PATCH 6/8] io_uring: optimise io_import_iovec nonblock passing Pavel Begunkov
2021-10-14 15:10 ` [PATCH 7/8] io_uring: clean up io_import_iovec Pavel Begunkov
2021-10-14 15:10 ` [PATCH 8/8] io_uring: rearrange io_read()/write() Pavel Begunkov
2021-10-16 22:52   ` Noah Goldstein
2021-10-16 23:25     ` Pavel Begunkov
2021-10-17  1:35       ` Noah Goldstein [this message]
2021-10-14 18:17 ` [PATCH for-next 0/8] read/write cleanup Jens Axboe

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