Re: [PATCH v2 0/4] singly linked list for chains

[Jens Axboe <axboe@kernel.dk>]

On 10/30/20 6:46 AM, Pavel Begunkov wrote:
> On 28/10/2020 14:18, Jens Axboe wrote:
>> On 10/27/20 5:25 PM, Pavel Begunkov wrote:
>>> v2: split the meat patch.
>>>
>>> I did not re-benchmark it, but as stated before: 5030 vs 5160 KIOPS by a
>>> naive (consistent) nop benchmark that submits 32 linked nops and then
>>> submits them in a loop. Worth trying with some better hardware.
>>
>> Applied for 5.11 - I'll give it a spin here too and see if I find any
>> improvements. But a smaller io_kiocb is always a win.
> 
> Might be a good time for a generic single list. There are at least 3
> places I remember: bio, io-wq, io_uring

Yes, kind of weird that we don't have one. There's the normal doubly
linked one, and then there's the single head for hash tables. But I
could not find anything good for io-wq, which is why I rolled my own.
Would be nice to turn it into a generic one and reuse it everywhere (and
I bet it would grow more users).

The lockless lists (llist) is singular, but overkill if you already have
locking you're under.

-- 
Jens Axboe