vulkan: Add vk_clock_gettime and vk_time_max_deviation

These two new function are based on {anv,radv}_clock_gettime
and some other common code between radv and anv.

These new functions allow these drivers to share code and
more drivers can use it in the future.

v2: Drop the anv/radv changes in this commit (Yiwei Zhang)
v3: Add #ifndef _WIN32

Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com> (v1)
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com> (v1)
Signed-off-by: Igor Torrente <igor.torrente@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18281>

src/vulkan/runtime/vk_device.c

@@ -527,6 +527,27 @@ vk_common_DeviceWaitIdle(VkDevice _device)
    return VK_SUCCESS;
 }
 
+#ifndef _WIN32
+
+uint64_t
+vk_clock_gettime(clockid_t clock_id)
+{
+   struct timespec current;
+   int ret;
+
+   ret = clock_gettime(clock_id, &current);
+#ifdef CLOCK_MONOTONIC_RAW
+   if (ret < 0 && clock_id == CLOCK_MONOTONIC_RAW)
+      ret = clock_gettime(CLOCK_MONOTONIC, &current);
+#endif
+   if (ret < 0)
+      return 0;
+
+   return (uint64_t)current.tv_sec * 1000000000ULL + current.tv_nsec;
+}
+
+#endif //!_WIN32
+
 #define CORE_FEATURE(feature) features->feature = core->feature
 
 bool

src/vulkan/runtime/vk_device.h

@@ -350,6 +350,56 @@ vk_device_check_status(struct vk_device *device)
    return result;
 }
 
+#ifndef _WIN32
+
+uint64_t
+vk_clock_gettime(clockid_t clock_id);
+
+static inline uint64_t
+vk_time_max_deviation(uint64_t begin, uint64_t end, uint64_t max_clock_period)
+{
+    /*
+     * The maximum deviation is the sum of the interval over which we
+     * perform the sampling and the maximum period of any sampled
+     * clock. That's because the maximum skew between any two sampled
+     * clock edges is when the sampled clock with the largest period is
+     * sampled at the end of that period but right at the beginning of the
+     * sampling interval and some other clock is sampled right at the
+     * beginning of its sampling period and right at the end of the
+     * sampling interval. Let's assume the GPU has the longest clock
+     * period and that the application is sampling GPU and monotonic:
+     *
+     *                               s                 e
+     *			 w x y z 0 1 2 3 4 5 6 7 8 9 a b c d e f
+     *	Raw              -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
+     *
+     *                               g
+     *		  0         1         2         3
+     *	GPU       -----_____-----_____-----_____-----_____
+     *
+     *                                                m
+     *					    x y z 0 1 2 3 4 5 6 7 8 9 a b c
+     *	Monotonic                           -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
+     *
+     *	Interval                     <----------------->
+     *	Deviation           <-------------------------->
+     *
+     *		s  = read(raw)       2
+     *		g  = read(GPU)       1
+     *		m  = read(monotonic) 2
+     *		e  = read(raw)       b
+     *
+     * We round the sample interval up by one tick to cover sampling error
+     * in the interval clock
+     */
+
+   uint64_t sample_interval = end - begin + 1;
+
+   return sample_interval + max_clock_period;
+}
+
+#endif //!_WIN32
+
 PFN_vkVoidFunction
 vk_device_get_proc_addr(const struct vk_device *device,
                         const char *name);