[lkml]   [2011]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Approaches to making io_submit not block
On 2011-08-30 16:19, Daniel Ehrenberg wrote:
> On Tue, Aug 30, 2011 at 2:37 PM, Jens Axboe <> wrote:
>> On 2011-08-30 15:30, Jeff Moyer wrote:
>>> Daniel Ehrenberg <> writes:
>>>> Hi Jens, Jeff,
>>>> I just sent a letter to LKML wondering about changes to io_submit that
>>>> I'm thinking of working on. Based on your past contributions to this
>>>> area, I'd really like to know what you think of this plan--how well it
>>>> matches with the existing design, the potential for inclusion in
>>>> upstream Linux, if you see problems.
>>> Hi, Dan,
>>> Thanks for taking the time to make AIO better! There is a mailing list
>>> for aio discussions:, so please CC that in the
>>> future (I don't read lkml anymore).
>>> Right now I'm a bit inundated, so I can't give this a proper review.
>>> I should be able to free up some time in the next two weeks, though.
>>> In the mean time, you can google for suparna's retry-based aio patches.
>>> Specifically, take a look at how she used prepare_to_wait/finish_wait.
>>> If you haven't done any empirical tests to see where io_submit blocks,
>>> there is a sample systemtap script for that:
>>> Other attempts at non-blocking aio were off the deep end: fibrils and
>>> syslets. Fibrils didn't go anywhere because Ingo didn't like them (for
>>> good reason, they essentially introduced another scheduling layer).
>>> Syslets didn't go anywhere b/c they were insane (returned to the
>>> user-space process with a different PID, among other things!).
>>> If you do go forward in the meantime, you can likely use EIOCBRETRY
>>> instead of EAGAIN.
>>> I hope that helps!
>> FWIW, I updated the buffered AIO retry patches some time after Suparna
>> droped them. By the date stamp in my branch, they are now 23 months
>> old... Anyway, at least it's more recent, you can find them here:
>> --
>> Jens Axboe
> Thanks! Do you know why the patches weren't merged? I can't find much
> discussion about them.

Not quite sure, and after working on them and fixing thing up, I don't
even think they are that complex or intrusive (which I think otherwise
would've been the main objection). Andrew may know/remember.

Jens Axboe

 \ /
  Last update: 2011-08-31 00:35    [W:0.152 / U:8.540 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site