Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster

On 14/07/2020 11:07, Miklos Szeredi wrote:

On Tue, Jul 14, 2020 at 8:51 AM Pavel Machek [off-list ref] wrote:

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Hi!

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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.

I think that's quite important as io_uring becomes mainstream.

-- 
Pavel Begunkov