Re: [PATCH 1/2] scsi_host: add support for request batching

Ming Lei
2019-07-05T01:01:15Z

On Mon, Jun 3, 2019 at 4:16 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 31/05/19 05:27, Ming Lei wrote:
> > It should be fine to implement scsi_commit_rqs() as:
> >
> > if (shost->hostt->commit_rqs)
> > shost->hostt->commit_rqs(shost, hctx->queue_num);
> >
> > then scsi_mq_ops_no_commit can be saved.
> >
> > Because .commit_rqs() is only called when BLK_STS_*_RESOURCE is
> > returned from scsi_queue_rq(), at that time shost->hostt->commit_rqs should
> > have been hit from cache given .queuecommand is called via
> > host->hostt->queuecommand.
>
> This is not about d-cache, it's about preserving the heuristics that
> blk-mq applies depending on whether commit_rqs is there or not.

Fair enough, at least difference would be made by the check in
blk_mq_make_request() if scsi_commit_rqs is provided unconditionally,
so looks fine:

Reviewed-by: Ming Lei <ming.lei@redhat.com>

Thanks,
Ming Lei