Re: [PATCH v6 1/4] block: Make fair tag sharing configurable

[Yu Kuai <yukuai1@huaweicloud.com>]

Hi,

在 2024/01/16 10:59, Bart Van Assche 写道:
> On 1/14/24 22:18, Yu Kuai wrote:
>> Can you take a look at my previous patset if you haven't? And it'll
>> be great to hear from your comments.
>>
>> https://lore.kernel.org/all/20231021154806.4019417-1-yukuai1@huaweicloud.com/ 
>>
> 
> Something is missing from the cover letter of that patch series:
> measurements that show the impact of that patch series on the maximum
> IOPS that can be achieved with the null_blk driver. I'm afraid that the
> performance impact of that patch series will be larger than what is 
> acceptable.

Hi,

This version is just RFC, and is focusing on the method. I ran some
tests on null_blk in my VM and didn't notice performace regression. My
idea is that I already make this patchset complicated, and I'm looking
for some comments for this patchset without spending too much time on
this blindly.

I'll provide null_blk tests result in the next version if anyone thinks
the approch is acceptable:

1) add a new field 'available_tags' and update it in slow path, hence
fast path hctx_may_queue() won't be affected.
2) delay tag sharing untill failed to get driver tag;
3) add a timer per shared tags to balance shared tags;

Thanks,
Kuai


> 
> Thanks,
> 
> Bart.
> 
> .
>