Re: [PATCH v2] scsi: target: Save a few cycles in transport_lookup_[cmd|tmr]_lun()

[Christophe JAILLET]

Le 16/08/2022 à 08:06, Chaitanya Kulkarni a écrit :
> On 8/15/22 13:52, Christophe JAILLET wrote:
> > Use percpu_ref_tryget_live_rcu() instead of percpu_ref_tryget_live() to
> > save a few cycles when it is known that the rcu lock is already
> > taken/released.
> >
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> do you have a quantitative data that shows actual savings of cycles?
>
> -ck

Some numbers were given for io_uring by the one who introduced 
percpu_ref_tryget_live_rcu().

See [1].

I don't have specific numbers for the patch against scsi.

CJ


[1]: 
https://lore.kernel.org/linux-kernel/cover.1634822969.git.asml.silence@xxxxxxxxx/