Re: uring regression - lost write request

[Jens Axboe <axboe@kernel.dk>]

On 11/9/21 4:24 PM, Jens Axboe wrote:
> On 11/9/21 3:58 PM, Daniel Black wrote:
>>> On Sat, Oct 30, 2021 at 6:30 PM Salvatore Bonaccorso <carnil@debian.org> wrote:
>>>> Were you able to pinpoint the issue?
>>
>> While I have been unable to reproduce this on a single cpu, Marko can
>> repeat a stall on a dual Broadwell chipset on kernels:
>>
>> * 5.15.1 - https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.1
>> * 5.14.16 - https://packages.debian.org/sid/linux-image-5.14.0-4-amd64
>>
>> Detailed observations:
>> https://jira.mariadb.org/browse/MDEV-26674
>>
>> The previous script has been adapted to use MariaDB-10.6 package and
>> sysbench to demonstrate a workload, I've changed Marko's script to
>> work with the distro packages and use innodb_use_native_aio=1.
>>
>> MariaDB packages:
>>
>> https://mariadb.org/download/?t=repo-config
>> (needs a distro that has liburing userspace libraries as standard support)
>>
>> Script:
>>
>> https://jira.mariadb.org/secure/attachment/60358/Mariabench-MDEV-26674-io_uring-1
>>
>> The state is achieved either when the sysbench prepare stalls, or the
>> tps printed at 5 second intervals falls to 0.
> 
> Thanks, this is most useful! I'll take a look at this.

Would it be possible to turn this into a full reproducer script?
Something that someone that knows nothing about mysqld/mariadb can just
run and have it reproduce. If I install the 10.6 packages from above,
then it doesn't seem to use io_uring or be linked against liburing.

The script also seems to assume that various things are setup
appropriately, like SRCTREE, MDIR, etc.

-- 
Jens Axboe