Re: [Intel-gfx] [PATCH 13/18] drm/i915/guc: Relax CTB response timeout

From: Matthew Brost <matthew.brost@intel.com>
To: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 13/18] drm/i915/guc: Relax CTB response timeout
Date: Wed, 26 May 2021 10:38:08 -0700	[thread overview]
Message-ID: <20210526173808.GA31459@sdutt-i7> (raw)
In-Reply-To: <cef31e1d-7502-78ae-84bd-60daaca01732@intel.com>

On Wed, May 26, 2021 at 02:25:26PM +0200, Michal Wajdeczko wrote:
> 
> 
> On 26.05.2021 08:42, Matthew Brost wrote:
> > From: Michal Wajdeczko <michal.wajdeczko@intel.com>
> > 
> > In upcoming patch we will allow more CTB requests to be sent in
> > parallel to the GuC for processing, so we shouldn't assume any more
> > that GuC will always reply without 10ms.
> > 
> > Use bigger value from CONFIG_DRM_I915_GUC_CTB_TIMEOUT instead.
> > 
> > v2: Add CONFIG_DRM_I915_GUC_CTB_TIMEOUT config option
> > 
> > Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > Reviewed-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >  drivers/gpu/drm/i915/Kconfig.profile      | 9 +++++++++
> >  drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 5 ++++-
> >  2 files changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile
> > index 39328567c200..68ac707755d2 100644
> > --- a/drivers/gpu/drm/i915/Kconfig.profile
> > +++ b/drivers/gpu/drm/i915/Kconfig.profile
> > @@ -38,6 +38,15 @@ config DRM_I915_USERFAULT_AUTOSUSPEND
> >  	  May be 0 to disable the extra delay and solely use the device level
> >  	  runtime pm autosuspend delay tunable.
> >  
> > +config DRM_I915_GUC_CTB_TIMEOUT
> > +	int "How long to wait for the GuC to make forward progress on CTBs (ms)"
> 
> maybe worth to provide here explicit allowed range:
> 
> 	range 10 60000
> 
> and then we can skip runtime adjustment for minimum 10ms timeout

Didn't know this option, done.

> 
> > +	default 1500 # milliseconds
> > +	help
> > +	  Configures the default timeout waiting for GuC the to make forward
> > +	  progress on CTBs. e.g. Waiting for a response to requeset.
> 
> typo
>

Fixed.

Matt

> > +
> > +	  A minimum value of 10 ms is allowed.
> > +
> >  config DRM_I915_HEARTBEAT_INTERVAL
> >  	int "Interval between heartbeat pulses (ms)"
> >  	default 2500 # milliseconds
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > index 916c2b80c841..5b0dece7a7cd 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > @@ -436,6 +436,7 @@ static int ct_write(struct intel_guc_ct *ct,
> >   */
> >  static int wait_for_ct_request_update(struct ct_request *req, u32 *status)
> >  {
> > +	long timeout;
> >  	int err;
> >  
> >  	/*
> > @@ -443,10 +444,12 @@ static int wait_for_ct_request_update(struct ct_request *req, u32 *status)
> >  	 * up to that length of time, then switch to a slower sleep-wait loop.
> >  	 * No GuC command should ever take longer than 10ms.
> >  	 */
> > +	timeout = max(10, CONFIG_DRM_I915_GUC_CTB_TIMEOUT);
> > +
> >  #define done INTEL_GUC_MSG_IS_RESPONSE(READ_ONCE(req->status))
> >  	err = wait_for_us(done, 10);
> >  	if (err)
> > -		err = wait_for(done, 10);
> > +		err = wait_for(done, timeout);
> >  #undef done
> >  
> >  	if (unlikely(err))
> > 
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