[Intel-gfx] [PATCH 03/21] drm/i915/gem: Set the watchdog timeout directly in intel_context_set_gem

[Jason Ekstrand]

On Fri, Apr 30, 2021 at 6:18 AM Tvrtko Ursulin
<tvrtko.ursulin at linux.intel.com> wrote:
>
>
> On 29/04/2021 15:54, Jason Ekstrand wrote:
> > On Thu, Apr 29, 2021 at 3:04 AM Tvrtko Ursulin
> > <tvrtko.ursulin at linux.intel.com> wrote:
> >>
> >>
> >> On 28/04/2021 18:24, Jason Ekstrand wrote:
> >>> On Wed, Apr 28, 2021 at 10:55 AM Tvrtko Ursulin
> >>> <tvrtko.ursulin at linux.intel.com> wrote:
> >>>> On 23/04/2021 23:31, Jason Ekstrand wrote:
> >>>>> Instead of handling it like a context param, unconditionally set it when
> >>>>> intel_contexts are created.  This doesn't fix anything but does simplify
> >>>>> the code a bit.
> >>>>>
> >>>>> Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
> >>>>> ---
> >>>>>     drivers/gpu/drm/i915/gem/i915_gem_context.c   | 43 +++----------------
> >>>>>     .../gpu/drm/i915/gem/i915_gem_context_types.h |  4 --
> >>>>>     drivers/gpu/drm/i915/gt/intel_context_param.h |  3 +-
> >>>>>     3 files changed, 6 insertions(+), 44 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> >>>>> index 35bcdeddfbf3f..1091cc04a242a 100644
> >>>>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> >>>>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> >>>>> @@ -233,7 +233,11 @@ static void intel_context_set_gem(struct intel_context *ce,
> >>>>>             intel_engine_has_timeslices(ce->engine))
> >>>>>                 __set_bit(CONTEXT_USE_SEMAPHORES, &ce->flags);
> >>>>>
> >>>>> -     intel_context_set_watchdog_us(ce, ctx->watchdog.timeout_us);
> >>>>> +     if (IS_ACTIVE(CONFIG_DRM_I915_REQUEST_TIMEOUT) &&
> >>>>> +         ctx->i915->params.request_timeout_ms) {
> >>>>> +             unsigned int timeout_ms = ctx->i915->params.request_timeout_ms;
> >>>>> +             intel_context_set_watchdog_us(ce, (u64)timeout_ms * 1000);
> >>>>
> >>>> Blank line between declarations and code please, or just lose the local.
> >>>>
> >>>> Otherwise looks okay. Slight change that same GEM context can now have a
> >>>> mix of different request expirations isn't interesting I think. At least
> >>>> the change goes away by the end of the series.
> >>>
> >>> In order for that to happen, I think you'd have to have a race between
> >>> CREATE_CONTEXT and someone smashing the request_timeout_ms param via
> >>> sysfs.  Or am I missing something?  Given that timeouts are really
> >>> per-engine anyway, I don't think we need to care too much about that.
> >>
> >> We don't care, no.
> >>
> >> For completeness only - by the end of the series it is what you say. But
> >> at _this_ point in the series though it is if modparam changes at any
> >> point between context create and replacing engines. Which is a change
> >> compared to before this patch, since modparam was cached in the GEM
> >> context so far. So one GEM context was a single request_timeout_ms.
> >
> > I've added the following to the commit message:
> >
> > It also means that sync files exported from different engines on a
> > SINGLE_TIMELINE context will have different fence contexts.  This is
> > visible to userspace if it looks at the obj_name field of
> > sync_fence_info.
> >
> > How's that sound?
>
> Wrong thread but sounds good.
>
> I haven't looked into the fence merge logic apart from noticing context
> is used there. So I'd suggest a quick look there on top, just to make
> sure merging logic does not hold any surprises if contexts start to
> differ. Probably just results with more inefficiency somewhere, in theory.

Looked at it yesterday.  It really does just create a fence array with
all the fences. :-)

--Jason