Re: [PATCH v7 00/15] io-uring/xfs: support async buffered writes

[Stefan Roesch <shr@fb.com>]

On 6/3/22 6:04 AM, Jens Axboe wrote:
> On 6/2/22 8:43 PM, Dave Chinner wrote:
>> On Thu, Jun 02, 2022 at 02:09:00AM -0600, Jens Axboe wrote:
>>> On 6/1/22 3:01 PM, Stefan Roesch wrote:
>>>> This patch series adds support for async buffered writes when using both
>>>> xfs and io-uring. Currently io-uring only supports buffered writes in the
>>>> slow path, by processing them in the io workers. With this patch series it is
>>>> now possible to support buffered writes in the fast path. To be able to use
>>>> the fast path the required pages must be in the page cache, the required locks
>>>> in xfs can be granted immediately and no additional blocks need to be read
>>>> form disk.
>>>
>>> This series looks good to me now, but will need some slight rebasing
>>> since the 5.20 io_uring branch has split up the code a bit. Trivial to
>>> do though, I suspect it'll apply directly if we just change
>>> fs/io_uring.c to io_uring/rw.c instead.
>>>
>>> The bigger question is how to stage this, as it's touching a bit of fs,
>>> mm, and io_uring...
>>
>> What data integrity testing has this had? Has it been run through a
>> few billion fsx operations with w/ io_uring read/write enabled?
> 
> I'll let Stefan expand on this, but just mention what I know - it has
> been fun via fio at least. Each of the performance tests were hour long
> each, and also specific test cases were written to test the boundary
> conditions of what pages of a range where in page cache, etc. Also with
> data verification.
> 

I performed the following tests:
- fio tests with various block sizes and different modes (psysnc, io_uring, libaio)
- fsx tests with one billion ops
- individual test program
  - to test with different block sizes
  - test short writes
  - test holes
  - test without readahead

> Don't know if fsx specifically has been used it.
>