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Message-Id: <20230324220013.191795-1-robdclark@gmail.com>
Date: Fri, 24 Mar 2023 15:00:13 -0700
From: Rob Clark <robdclark@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
Rob Clark <robdclark@...omium.org>,
Rob Clark <robdclark@...il.com>,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] drm/msm: Avoid rounding down to zero jiffies
From: Rob Clark <robdclark@...omium.org>
If userspace asked for a timeout greater than zero, but less than a
jiffy, they clearly weren't planning on spinning. So it is better
to round up to one.
This fixes an issue with supertuxkart that was (for some reason)
spinning on a gl sync with 1ms timeout. CPU time for a demo lap
drops from:
15.83user 20.98system 0:47.46elapsed 77%CPU
to:
8.84user 2.30system 0:46.67elapsed 23%CPU
Signed-off-by: Rob Clark <robdclark@...omium.org>
---
drivers/gpu/drm/msm/msm_drv.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 9f0c184b02a0..7936aa6cad03 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -548,7 +548,7 @@ static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ);
}
- return clamp(remaining_jiffies, 0LL, (s64)INT_MAX);
+ return clamp(remaining_jiffies, 1LL, (s64)INT_MAX);
}
/* Driver helpers */
--
2.39.2
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