Re: [PATCH RFC v4 1/3] block: add BIO_COMPLETE_IN_TASK for task-context completion

[Tal Zussman <tz2294@columbia.edu>]

On 4/8/26 7:36 PM, Jens Axboe wrote:
> On Apr 8, 2026, at 4:51 PM, Tal Zussman <tz2294@columbia.edu> wrote:
>>> On 4/8/26 3:51 PM, Jens Axboe wrote:
>>>> On 4/8/26 12: 48 PM, Tal Zussman wrote: > On 3/25/26 4: 14 PM, Jens Axboe wrote:
>>>> 
>>>> Thanks! I'm going to give Dave's llist suggestion a shot on top of
>>>> this as it seems like it'll simplify this nicely. Looks like that'll
>>>> involve turning bio::bi_next into a union with a struct llist_node.
>>> 
>>> Since these lists can get long, I'd keep an eye on llist reversal
>>> overhead there...
>>> 
>> 
>> Going to send v5 shortly -- tested with and without the llist reversal and
>> it didn't seem to make much of a difference. This was on a single-disk VM
>> though, so any stress testing you could do would be very helpful.
>> 
> 
> With all due respect, a single test like that isn’t going to be that useful. I’d be wary of making that change willy nilly and just thinking “it’s fine, worked fine on the one case I tested”.

Understood -- unfortunately that's what I have access to at the moment. I
can requisition a machine with 2, maybe 3 disks, and test more thoroughly on
that before sending the next version, but that'll take a few days. You had
previously offered to test on your big box, so was hoping that was still on
the table :)
(Although Christoph seems to have proposed moving away from llist again)

> —
> Jens Axboe
>