lkml.org 
[lkml]   [2020]   [Jul]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 4/4] io_uring: add support for zone-append
From
Date
On 7/10/20 7:10 AM, Christoph Hellwig wrote:
> On Fri, Jul 10, 2020 at 12:35:43AM +0530, Kanchan Joshi wrote:
>> Append required special treatment (conversion for sector to bytes) for io_uring.
>> And we were planning a user-space wrapper to abstract that.
>>
>> But good part (as it seems now) was: append result went along with cflags at
>> virtually no additional cost. And uring code changes became super clean/minimal
>> with further revisions.
>> While indirect-offset requires doing allocation/mgmt in application,
>> io-uring submission
>> and in completion path (which seems trickier), and those CQE flags
>> still get written
>> user-space and serve no purpose for append-write.
>
> I have to say that storing the results in the CQE generally make
> so much more sense. I wonder if we need a per-fd "large CGE" flag
> that adds two extra u64s to the CQE, and some ops just require this
> version.

I have been pondering the same thing, we could make certain ops consume
two CQEs if it makes sense. It's a bit ugly on the app side with two
different CQEs for a request, though. We can't just treat it as a large
CQE, as they might not be sequential if we happen to wrap. But maybe
it's not too bad.

--
Jens Axboe

\
 
 \ /
  Last update: 2020-07-10 16:10    [W:0.084 / U:0.572 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site