Re: [RFC PATCH v2 09/19] scsi: core: increase/decrease target_busy without check can_queue

[Wenchao Hao]

On 2023/9/6 7:55, Mike Christie wrote:
> On 9/1/23 4:41 AM, Wenchao Hao wrote:
> > This is preparation for a genernal target based error handle strategy
> > to check if to wake up actual error handler.
> >
> > Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
> > ---
> >   drivers/scsi/scsi_lib.c | 11 ++++-------
> >   1 file changed, 4 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index db0a42fe49c0..4a7fb48aa60f 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -293,8 +293,7 @@ void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd)
> >   
> >   	scsi_dec_host_busy(shost, cmd);
> >   
> > -	if (starget->can_queue > 0)
> > -		atomic_dec(&starget->target_busy);
> > +	atomic_dec(&starget->target_busy);
> >   
>
> Ming had found that removing the atomics improves perf.
> Since most drivers didn't care about the target level counters
> it was moved to the can_queue check so only drivers using the
> feature suffer the perf hit.
>
> Your patch should do the same.
Would update in next version