Re: [PATCH 2/2] block/mq-deadline: fallback to per-cpu insertion buckets under contention

Jens Axboe
2024-01-18T18:56:12Z

On 1/18/24 11:53 AM, Bart Van Assche wrote:
> On 1/18/24 10:33, Jens Axboe wrote:
>> On 1/18/24 11:31 AM, Bart Van Assche wrote:
>>> On 1/18/24 10:04, Jens Axboe wrote:
>>>> If we attempt to insert a list of requests but someone else is already
>>>> running an insertion, then fallback to queueing it internally and let
>>>> the existing inserter finish the operation.
>>>
>>> Because this patch adds significant complexity: what are the use cases
>>> that benefit from this kind of optimization? Are these perhaps workloads
>>> on systems with many CPU cores and fast storage? If the storage is fast,
>>> why to use mq-deadline instead of "none" as I/O-scheduler?
>>
>> You and others complain that mq-deadline is slow and doesn't scale,
>> these two patches help improve that situation. Not sure why this is even
>> a question?
>
> How much does this patch improve performance?

Do you need me to link the cover letter that you were CC'ed on?

--
Jens Axboe