Re: [PATCH 2/2] blk-mq: ensure a q_usage_counter reference is held when splitting bios

Jens Axboe
2024-01-12T16:10:46Z

On 1/12/24 7:25 AM, Christoph Hellwig wrote:
> On Fri, Jan 12, 2024 at 07:22:18AM -0700, Jens Axboe wrote:
>> Yep it is pretty cheap, but it's not free. Here's a test where we just
>> grab a ref and drop it, which should arguably be cheaper than doing a
>> ref at the top and dropping it at the bottom due to temporal locality:
>>
>> 5.01% +0.86% [kernel.vmlinux] [k] blk_mq_submit_bio
>
> Ok. Do you want to send out your version formally?

Sure, can do. I'll pick your first patch here as that one makes
sense separately.

--
Jens Axboe