Re: [PATCH V8 00/33] loop: Issue O_DIRECT aio using bio_vec

[Ming Lei]

On Thu, Jan 1, 2015 at 6:35 AM, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> On Wed, Dec 31, 2014 at 10:52 PM, Dave Kleikamp
> <dave.kleikamp@xxxxxxxxxx> wrote:
>> On 12/31/2014 02:38 PM, Sedat Dilek wrote:
>>>
>>> What has happened to that aio_loop patchset?
>>> Is it in Linux-next?
>>> ( /me started to play with "block: loop: convert to blk-mq (v3)", so I
>>> recalled this other improvement. )
>>
>> It met with some harsh resistance, so I backed off on it. Then Al Viro
>> got busy re-writing the iov_iter infrastructure and I put my patchset on
>> the shelf to look at later. Then Ming Lei submitted more up-to-date
>> patchset: https://lkml.org/lkml/2014/8/6/175
>>
>> It looks like Ming is currently only pushing the first half of that
>> patchset. I don't know what his plans are for the last three patches:
>>
>> aio: add aio_kernel_() interface
>> fd/direct-io: introduce should_dirty for kernel aio
>> block: loop: support to submit I/O via kernel aio based
>>
>
> I tested with block-mq-v3 (for next-20141231) [1] and this looks promising [2].
>
> Maybe Ming can say what the plan is with the missing parts.

I have compared kernel aio based loop-mq(the other 3 aio patches
against loop-mq v2, [1]) with loop-mq v3, looks the data isn't
better than loop-mq v3.

kernel aio based approach requires direct I/O, at least direct write
shouldn't be good as page cache write, IMO.

So I think we need to investigate kernel aio based approach further
wrt. loop improvement.

[1] http://marc.info/?l=linux-kernel&m=140941494422520&w=2

Thanks,
Ming Lei
>
> - Sedat -
>
> [1] http://marc.info/?l=linux-kernel&m=142003226701471&w=2
> [2]http://marc.info/?l=linux-kernel&m=142006516408381&w=2
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