On Thu, Sep 20, 2018 at 10:43 PM Jason Gunthorpe <jgg@xxxxxxxxxxxx> wrote:
>
> On Thu, Sep 20, 2018 at 01:08:32PM -0400, Devesh Sharma wrote:
> > Remove the lock around the doorbell. It isn't necessary
> > and was a bottleneck for multithreaded clients. Performance of
> > spdk improves by 40% with it removed.
> >
> > Signed-off-by: JD Zheng <jiandong.zheng@xxxxxxxxxxxx>
> > Signed-off-by: Jonathan Richardson <jonathan.richardson@xxxxxxxxxxxx>
> > Signed-off-by: Devesh Sharma <devesh.sharma@xxxxxxxxxxxx>
> > ---
> > providers/bnxt_re/db.c | 2 --
> > providers/bnxt_re/main.c | 1 -
> > providers/bnxt_re/main.h | 1 -
> > providers/bnxt_re/verbs.c | 2 --
> > 4 files changed, 6 deletions(-)
> >
> > diff --git a/providers/bnxt_re/db.c b/providers/bnxt_re/db.c
> > index a79f871..2896ceb 100644
> > --- a/providers/bnxt_re/db.c
> > +++ b/providers/bnxt_re/db.c
> > @@ -44,11 +44,9 @@ static void bnxt_re_ring_db(struct bnxt_re_dpi *dpi,
> > {
> > __le64 *dbval;
> >
> > - pthread_spin_lock(&dpi->db_lock);
> > dbval = (__le64 *)&hdr->indx;
> > udma_to_device_barrier();
> > iowrite64(dpi->dbpage, dbval);
> > - pthread_spin_unlock(&dpi->db_lock);
> > }
>
> Nope, you have to convert this provider to use the mmio accessor
> helpers if you want to do this.
>
> Ie get rid of iowrite64/iowrite32 and use the macros in util/mmio.h
>
> They provide the necessary guarentee for atomicity to allow the lock
> to be removed.
>
> Jason
Okay, this can be done. While removing the lock I was thinking what
will happen on the 32 bit platform. would those new apis handle 32bit
platforms too?
-Regards
Devesh
