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

Bart Van Assche
2024-01-18T18:53:01Z

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?

Thanks,

Bart.