On 11/15/2017 6:01 PM, Chris Wilson wrote:
Quoting Sagar Arun Kamble (2017-11-15 12:13:54)
From: Sourab Gupta <sourab.gupta@xxxxxxxxx>
Currently, we have the ability to only forward the GPU timestamps in the
samples (which are generated via OA reports). This limits the ability to
correlate these samples with the system events.
An ability is therefore needed to report timestamps in different clock
domains, such as CLOCK_MONOTONIC, in the perf samples to be of more
practical use to the userspace. This ability becomes important
when we want to correlate/plot GPU events/samples with other system events
on the same timeline (e.g. vblank events, or timestamps when work was
submitted to kernel, etc.)
The patch here proposes a mechanism to achieve this. The correlation
between gpu time and system time is established using the timestamp clock
associated with the command stream, abstracted as timecounter/cyclecounter
to retrieve gpu/system time correlated values.
v2: Added i915_driver_init_late() function to capture the new late init
phase for perf (Chris)
v3: Removed cross-timestamp changes.
Signed-off-by: Sourab Gupta <sourab.gupta@xxxxxxxxx>
Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@xxxxxxxxx>
Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sourab Gupta <sourab.gupta@xxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_perf.c | 27 +++++++++++++++++++++++++++
include/uapi/drm/i915_drm.h | 7 +++++++
2 files changed, 34 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 3b721d7..94ee924 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -336,6 +336,7 @@
#define SAMPLE_OA_REPORT BIT(0)
#define SAMPLE_GPU_TS BIT(1)
+#define SAMPLE_SYSTEM_TS BIT(2)
/**
* struct perf_open_properties - for validated properties given to open a stream
@@ -622,6 +623,7 @@ static int append_oa_sample(struct i915_perf_stream *stream,
struct drm_i915_perf_record_header header;
u32 sample_flags = stream->sample_flags;
u64 gpu_ts = 0;
+ u64 system_ts = 0;
header.type = DRM_I915_PERF_RECORD_SAMPLE;
header.pad = 0;
@@ -647,6 +649,23 @@ static int append_oa_sample(struct i915_perf_stream *stream,
if (copy_to_user(buf, &gpu_ts, I915_PERF_TS_SAMPLE_SIZE))
return -EFAULT;
+ buf += I915_PERF_TS_SAMPLE_SIZE;
+ }
+
+ if (sample_flags & SAMPLE_SYSTEM_TS) {
+ gpu_ts = get_gpu_ts_from_oa_report(stream, report);
Scope your variables. Stops us from being confused as to where else
gpu_ts or sys_ts may be reused. For instance I first thought you were
using SAMPLE_GPU_TS to initialise gpu_ts
Yes
+ /*
+ * XXX: timecounter_cyc2time considers time backwards if delta
+ * timestamp is more than half the max ns time covered by
+ * counter. It will be ~35min for 36 bit counter. If this much
+ * sampling duration is needed we will have to update tc->nsec
+ * by explicitly reading the timecounter (timecounter_read)
+ * before this duration.
+ */
+ system_ts = timecounter_cyc2time(&stream->tc, gpu_ts);
+
+ if (copy_to_user(buf, &system_ts, I915_PERF_TS_SAMPLE_SIZE))
+ return -EFAULT;
Advance buf.
Had kept advance logic only if there is new field to be added as this
advance is missing for
SAMPLE_OA_REPORT currently in drm-tip. Will fix.
Thanks for the review :)
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