[Intel-gfx] [RFC] tests/gem_ring_sync_copy: reduce memory usage

[Chris Wilson]

On Fri, Nov 28, 2014 at 04:34:08PM +0000, Gore, Tim wrote:
> 
> 
> > -----Original Message-----
> > From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> > Sent: Friday, November 28, 2014 4:20 PM
> > To: Lespiau, Damien
> > Cc: Gore, Tim; intel-gfx at lists.freedesktop.org
> > Subject: Re: [Intel-gfx] [RFC] tests/gem_ring_sync_copy: reduce memory
> > usage
> > 
> > On Fri, Nov 28, 2014 at 04:04:14PM +0000, Damien Lespiau wrote:
> > > On Fri, Nov 28, 2014 at 03:47:01PM +0000, Gore, Tim wrote:
> > > > N_buffers_load is still used. I am still submitting 1000 buffers to
> > > > the ring, its just that I use the same buffers over and over (hence the "i %
> > NUM_BUSY_BUFFERS").
> > > > So I only allocate 32 buffers, and each gets copied 1000/32 times,
> > > > so the ring is kept busy for as long as previously.
> > >
> > > Ah oops, yes, indeed. Looks good then, pushed, thanks for the patch.
> > 
> > The ring is kept as busy, but the queue depth is drastically reduced (from
> > N_buffers to 32). Since both numbers are arbitrary, I am not adverse to the
> > change, but I would feel happier if it was demonstrated that the new test is
> > still capable of detecting bugs deliberately introduced into the ring
> > synchronisation code.
> > -Chris
> > 
> 
> Excuse a rather novice question, but which queue depth is reduced?

We track on the object the last read/write request. If you reuse objects
the effective depth in the read/write queue is reduced, and this queue
is implicitly used when synchronising between rings.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre