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From: Stefan Metzmacher <metze@samba.org>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Cc: david@fromorbit.com, jmoyer@redhat.com
Subject: Re: [PATCHSET v2 0/2] io_uring: handle short reads internally
Date: Mon, 17 Aug 2020 11:25:56 +0200	[thread overview]
Message-ID: <4c79f6b2-552c-f404-8298-33beaceb9768@samba.org> (raw)
In-Reply-To: <20200814195449.533153-1-axboe@kernel.dk>


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Hi Jens,

> Since we've had a few cases of applications not dealing with this
> appopriately, I believe the safest course of action is to ensure that
> we don't return short reads when we really don't have to.
>
> The first patch is just a prep patch that retains iov_iter state over
> retries, while the second one actually enables just doing retries if
> we get a short read back.
> 
> This passes all my testing, both liburing regression tests but also
> tests that explicitly trigger internal short reads and hence retry
> based on current state. No short reads are passed back to the
> application.

Thanks! I was going to ask about exactly that :-)

It wasn't clear why returning short reads were justified by resulting
in better performance... As it means the application needs to do
a lot more work and syscalls.

Will this be backported?

metze


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  parent reply	other threads:[~2020-08-17  9:26 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-14 19:54 [PATCHSET v2 0/2] io_uring: handle short reads internally Jens Axboe
2020-08-14 19:54 ` [PATCH 1/2] io_uring: retain iov_iter state over io_read/io_write calls Jens Axboe
2020-08-14 19:54 ` [PATCH 2/2] io_uring: internally retry short reads Jens Axboe
2020-08-17  9:25 ` Stefan Metzmacher [this message]
2020-08-18  3:29   ` [PATCHSET v2 0/2] io_uring: handle short reads internally Jens Axboe
2020-08-18  4:12     ` Jens Axboe
2020-08-18  4:30       ` Jens Axboe
2020-08-18  7:40         ` Stefan Metzmacher
2020-08-18 14:44           ` Jens Axboe
2020-08-18 14:49             ` Anoop C S
2020-08-18 14:53               ` Jens Axboe
2020-08-18 15:23                 ` Jens Axboe
     [not found]                   ` <ad6cd95adb2e7622860fd9a80c19e48230ae2747.camel@cryptolab.net>
2020-08-19  8:31                     ` Stefan Metzmacher
2020-08-19 12:48                       ` Jens Axboe

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