Re: [PATCH v3 5/5] block/block-copy: use aio-task-pool API

[Vladimir Sementsov-Ogievskiy]

29.04.2020 14:55, Max Reitz wrote:
> On 29.04.20 08:10, Vladimir Sementsov-Ogievskiy wrote:
> > Run block_copy iterations in parallel in aio tasks.
> >
> > Changes:
> >    - BlockCopyTask becomes aio task structure. Add zeroes field to pass
> >      it to block_copy_do_copy
> >    - add call state - it's a state of one call of block_copy(), shared
> >      between parallel tasks. For now used only to keep information about
> >      first error: is it read or not.
> >    - convert block_copy_dirty_clusters to aio-task loop.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > ---
> >   block/block-copy.c | 104 +++++++++++++++++++++++++++++++++++++++------
> >   1 file changed, 91 insertions(+), 13 deletions(-)
> >
> > diff --git a/block/block-copy.c b/block/block-copy.c
> > index 5cf032c4d8..f5ef91f292 100644
> > --- a/block/block-copy.c
> > +++ b/block/block-copy.c
>
> [...]
>
> > @@ -261,6 +278,30 @@ void block_copy_set_progress_meter(BlockCopyState *s, 
> > ProgressMeter *pm)
> >       s->progress = pm;
> >   }
> >   
> > +/* Takes ownership on @task */
>
> Still *of

Ohhh, very sorry for it, I really forget to update the patch :(

> > +static coroutine_fn int block_copy_task_run(AioTaskPool *pool,
> > +                                            BlockCopyTask *task)
> > +{
> > +    if (!pool) {
> > +        int ret = task->task.func(&task->task);
> > +
> > +        g_free(task);
> > +        return ret;
> > +    }
> > +
> > +    aio_task_pool_wait_slot(pool);
> > +    if (aio_task_pool_status(pool) < 0) {
> > +        co_put_to_shres(task->s->mem, task->bytes);
> > +        block_copy_task_end(task, -EAGAIN);
>
> It looks like you may have missed my nit picks on v2 regarding this
> patch, so I’m going to ask again whether -ECANCELED might be better here
> (even though it still doesn’t really matter).

Hmm yes, sounds better in the context. And I don't see any specific usage of 
it, and don't remember why I've chosen EAGAIN :) Let's use ECANCELED.

> > +        g_free(task);
> > +        return aio_task_pool_status(pool);
>
> And whether it may be better to return a constant like -ECANCELED here,
> because how a previous task failed shouldn’t really concern this task
> (or its error code).

Looks correct, will change.

> > +    }
> > +
> > +    aio_task_pool_start_task(pool, &task->task);
> > +
> > +    return 0;
> > +}
> > +
> >   /*
> >    * block_copy_do_copy
> >    *
>
> [...]
>
> > @@ -525,25 +590,38 @@ static int coroutine_fn 
> > block_copy_dirty_clusters(BlockCopyState *s,
>
> [...]
>
> > +out:
> > +    if (aio) {
> > +        aio_task_pool_wait_all(aio);
> > +        if (ret == 0) {
> > +            ret = aio_task_pool_status(aio);
> > +        }
> > +        g_free(aio);
>
> I’d still prefer aio_task_pool_free().

a thousand apologies :(


--
Best regards,
Vladimir