Re: [PATCH v3 0/6] add persistent submission state

[Pavel Begunkov]

On 01/02/2020 01:22, Jens Axboe wrote:
> On 1/31/20 3:15 PM, Pavel Begunkov wrote:
>> Apart from unrelated first patch, this persues two goals:
>>
>> 1. start preparing io_uring to move resources handling into
>> opcode specific functions
>>
>> 2. make the first step towards long-standing optimisation ideas
>>
>> Basically, it makes struct io_submit_state embedded into ctx, so
>> easily accessible and persistent, and then plays a bit around that.
> 
> Do you have any perf/latency numbers for this? Just curious if we
> see any improvements on that front, cross submit persistence of
> alloc caches should be a nice sync win, for example, or even
> for peak iops by not having to replenish the pool for each batch.
> 
> I can try and run some here too.
> 

I tested the first version, but my drive is too slow, so it was only nops and
hence no offloading. Honestly, there waren't statistically significant results.
I'll rerun anyway.

I have a plan to reuse it for a tricky optimisation, but thinking twice, I can
just stash it until everything is done. That's not the first thing in TODO and
will take a while.


-- 
Pavel Begunkov

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