On 8/26/21 8:48 PM, Bart Van Assche wrote:

On 8/26/21 5:05 PM, Jens Axboe wrote:

quoted

On 8/26/21 6:03 PM, Bart Van Assche wrote:

quoted

Here is an overview of the tests I ran so far, all on the same test
setup:
* No I/O scheduler:               about 5630 K IOPS.
* Kernel v5.11 + mq-deadline:     about 1100 K IOPS.
* block-for-next + mq-deadline:   about  760 K IOPS.
* block-for-next with improved mq-deadline performance: about 970 K IOPS.

So we're still off by about 12%, I don't think that is good enough.
That's assuming that v5.11 + mq-deadline is the same as for-next with
the mq-deadline change reverted? Because that would be the key number to
compare it with.

With the patch series that is available at
https://github.com/bvanassche/linux/tree/block-for-next the same test reports
1090 K IOPS or only 1% below the v5.11 result. I will post that series on the
linux-block mailing list after I have finished testing that series.

OK sounds good. I do think we should just do the revert at this point,
any real fix is going to end up being bigger than I'd like at this
point. Then we can re-introduce the feature once we're happy with the
results.

-- 
Jens Axboe