[PATCH v2 6/6] drm/xe/client: Print runtime to fdinfo
Tvrtko Ursulin
tursulin at ursulin.net
Fri Apr 26 10:47:37 UTC 2024
On 24/04/2024 00:56, Lucas De Marchi wrote:
> Print the accumulated runtime for client when printing fdinfo.
> Each time a query is done it first does 2 things:
>
> 1) loop through all the exec queues for the current client and
> accumulate the runtime, per engine class. CTX_TIMESTAMP is used for
> that, being read from the context image.
>
> 2) Read a "GPU timestamp" that can be used for considering "how much GPU
> time has passed" and that has the same unit/refclock as the one
> recording the runtime. RING_TIMESTAMP is used for that via MMIO.
>
> Since for all current platforms RING_TIMESTAMP follows the same
> refclock, just read it once, using any first engine.
>
> This is exported to userspace as 2 numbers in fdinfo:
>
> drm-cycles-<class>: <RUNTIME>
> drm-total-cycles-<class>: <TIMESTAMP>
>
> Userspace is expected to collect at least 2 samples, which allows to
> know the client engine busyness as per:
>
> RUNTIME1 - RUNTIME0
> busyness = ---------------------
> T1 - T0
>
> Another thing to point out is that it's expected that userspace will
> read any 2 samples every few seconds. Given the update frequency of the
> counters involved and that CTX_TIMESTAMP is 32-bits, the counter for
> each exec_queue can wrap around (assuming 100% utilization) after ~200s.
> The wraparound is not perceived by userspace since it's just accumulated
> for all the exec_queues in a 64-bit counter), but the measurement will
> not be accurate if the samples are too far apart.
>
> This could be mitigated by adding a workqueue to accumulate the counters
> every so often, but it's additional complexity for something that is
> done already by userspace every few seconds in tools like gputop (from
> igt), htop, nvtop, etc with none of them really defaulting to 1 sample
> per minute or more.
>
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> ---
> Documentation/gpu/drm-usage-stats.rst | 16 ++-
> Documentation/gpu/xe/index.rst | 1 +
> Documentation/gpu/xe/xe-drm-usage-stats.rst | 10 ++
> drivers/gpu/drm/xe/xe_drm_client.c | 138 +++++++++++++++++++-
> 4 files changed, 162 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/gpu/xe/xe-drm-usage-stats.rst
>
> diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
> index 6dc299343b48..421766289b78 100644
> --- a/Documentation/gpu/drm-usage-stats.rst
> +++ b/Documentation/gpu/drm-usage-stats.rst
> @@ -112,6 +112,17 @@ larger value within a reasonable period. Upon observing a value lower than what
> was previously read, userspace is expected to stay with that larger previous
> value until a monotonic update is seen.
>
> +- drm-total-cycles-<keystr>: <uint>
> +
> +Engine identifier string must be the same as the one specified in the
> +drm-cycles-<keystr> tag and shall contain the total number cycles for the given
> +engine.
> +
> +This is a timestamp in GPU unspecified unit that matches the update rate
> +of drm-cycles-<keystr>. For drivers that implement this interface, the engine
> +utilization can be calculated entirely on the GPU clock domain, without
> +considering the CPU sleep time between 2 samples.
Two opens.
1)
Do we need to explicity document that drm-total-cycles and drm-maxfreq
are mutually exclusive?
2)
Should drm-total-cycles for now be documents as driver specific?
I have added some more poeple in the cc who were involved with driver
fdinfo implementations if they will have an opinion.
I would say potentially yes, and promote it to common if more than one
driver would use it.
For instance I see panfrost has the driver specific drm-curfreq
(although isn't documenting it fully in panfrost.rst). And I have to say
it is somewhat questionable to expose the current frequency per fdinfo
per engine but not my call.
> +
> - drm-maxfreq-<keystr>: <uint> [Hz|MHz|KHz]
>
> Engine identifier string must be the same as the one specified in the
> @@ -168,5 +179,6 @@ be documented above and where possible, aligned with other drivers.
> Driver specific implementations
> -------------------------------
>
> -:ref:`i915-usage-stats`
> -:ref:`panfrost-usage-stats`
> +* :ref:`i915-usage-stats`
> +* :ref:`panfrost-usage-stats`
> +* :ref:`xe-usage-stats`
> diff --git a/Documentation/gpu/xe/index.rst b/Documentation/gpu/xe/index.rst
> index c224ecaee81e..3f07aa3b5432 100644
> --- a/Documentation/gpu/xe/index.rst
> +++ b/Documentation/gpu/xe/index.rst
> @@ -23,3 +23,4 @@ DG2, etc is provided to prototype the driver.
> xe_firmware
> xe_tile
> xe_debugging
> + xe-drm-usage-stats.rst
> diff --git a/Documentation/gpu/xe/xe-drm-usage-stats.rst b/Documentation/gpu/xe/xe-drm-usage-stats.rst
> new file mode 100644
> index 000000000000..ccb48733cbe3
> --- /dev/null
> +++ b/Documentation/gpu/xe/xe-drm-usage-stats.rst
> @@ -0,0 +1,10 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +
> +.. _xe-usage-stats:
> +
> +=======================================
> +Xe DRM client usage stats implemenation
> +=======================================
> +
> +.. kernel-doc:: drivers/gpu/drm/xe/xe_drm_client.c
> + :doc: DRM Client usage stats
> diff --git a/drivers/gpu/drm/xe/xe_drm_client.c b/drivers/gpu/drm/xe/xe_drm_client.c
> index 08f0b7c95901..0227383910fa 100644
> --- a/drivers/gpu/drm/xe/xe_drm_client.c
> +++ b/drivers/gpu/drm/xe/xe_drm_client.c
> @@ -2,6 +2,7 @@
> /*
> * Copyright © 2023 Intel Corporation
> */
> +#include "xe_drm_client.h"
>
> #include <drm/drm_print.h>
> #include <drm/xe_drm.h>
> @@ -12,9 +13,66 @@
> #include "xe_bo.h"
> #include "xe_bo_types.h"
> #include "xe_device_types.h"
> -#include "xe_drm_client.h"
> +#include "xe_exec_queue.h"
> +#include "xe_gt.h"
> +#include "xe_hw_engine.h"
> +#include "xe_pm.h"
> #include "xe_trace.h"
>
> +/**
> + * DOC: DRM Client usage stats
> + *
> + * The drm/xe driver implements the DRM client usage stats specification as
> + * documented in :ref:`drm-client-usage-stats`.
> + *
> + * Example of the output showing the implemented key value pairs and entirety of
> + * the currently possible format options:
> + *
> + * ::
> + *
> + * pos: 0
> + * flags: 0100002
> + * mnt_id: 26
> + * ino: 685
> + * drm-driver: xe
> + * drm-client-id: 3
> + * drm-pdev: 0000:03:00.0
> + * drm-total-system: 0
> + * drm-shared-system: 0
> + * drm-active-system: 0
> + * drm-resident-system: 0
> + * drm-purgeable-system: 0
> + * drm-total-gtt: 192 KiB
> + * drm-shared-gtt: 0
> + * drm-active-gtt: 0
> + * drm-resident-gtt: 192 KiB
> + * drm-total-vram0: 23992 KiB
> + * drm-shared-vram0: 16 MiB
> + * drm-active-vram0: 0
> + * drm-resident-vram0: 23992 KiB
> + * drm-total-stolen: 0
> + * drm-shared-stolen: 0
> + * drm-active-stolen: 0
> + * drm-resident-stolen: 0
> + * drm-cycles-rcs: 28257900
> + * drm-total-cycles-rcs: 7655183225
> + * drm-cycles-bcs: 0
> + * drm-total-cycles-bcs: 7655183225
> + * drm-cycles-vcs: 0
> + * drm-total-cycles-vcs: 7655183225
> + * drm-engine-capacity-vcs: 2
> + * drm-cycles-vecs: 0
> + * drm-total-cycles-vecs: 7655183225
> + * drm-engine-capacity-vecs: 2
> + * drm-cycles-ccs: 0
> + * drm-total-cycles-ccs: 7655183225
> + * drm-engine-capacity-ccs: 4
> + *
> + * Possible `drm-cycles-` key names are: `rcs`, `ccs`, `bcs`, `vcs`, `vecs` and
> + * "other".
> + */
> +
> +
> /**
> * xe_drm_client_alloc() - Allocate drm client
> * @void: No arg
> @@ -179,6 +237,83 @@ static void show_meminfo(struct drm_printer *p, struct drm_file *file)
> }
> }
>
> +static const u64 class_to_mask[] = {
> + [XE_ENGINE_CLASS_RENDER] = XE_HW_ENGINE_RCS_MASK,
> + [XE_ENGINE_CLASS_VIDEO_DECODE] = XE_HW_ENGINE_VCS_MASK,
> + [XE_ENGINE_CLASS_VIDEO_ENHANCE] = XE_HW_ENGINE_VECS_MASK,
> + [XE_ENGINE_CLASS_COPY] = XE_HW_ENGINE_BCS_MASK,
> + [XE_ENGINE_CLASS_OTHER] = XE_HW_ENGINE_GSCCS_MASK,
> + [XE_ENGINE_CLASS_COMPUTE] = XE_HW_ENGINE_CCS_MASK,
> +};
> +
> +static void show_runtime(struct drm_printer *p, struct drm_file *file)
> +{
> + struct xe_file *xef = file->driver_priv;
> + struct xe_device *xe = xef->xe;
> + struct xe_gt *gt;
> + struct xe_hw_engine *hwe;
> + struct xe_exec_queue *q;
> + unsigned long i, id_hwe, id_gt, capacity[XE_ENGINE_CLASS_MAX] = { };
> + u64 gpu_timestamp, engine_mask = 0;
> + bool gpu_stamp = false;
> +
> + xe_pm_runtime_get(xe);
> +
> + /* Accumulate all the exec queues from this client */
> + mutex_lock(&xef->exec_queue.lock);
> + xa_for_each(&xef->exec_queue.xa, i, q)
> + xe_exec_queue_update_runtime(q);
> + mutex_unlock(&xef->exec_queue.lock);
> +
> +
> + /* Calculate capacity of each engine class */
> + BUILD_BUG_ON(ARRAY_SIZE(class_to_mask) != XE_ENGINE_CLASS_MAX);
> + for_each_gt(gt, xe, id_gt)
> + engine_mask |= gt->info.engine_mask;
> + for (i = 0; i < XE_ENGINE_CLASS_MAX; i++)
> + capacity[i] = hweight64(engine_mask & class_to_mask[i]);
FWIW the above two loops are static so could store capacity in struct
xe_device.
> +
> + /*
> + * Iterate over all engines, printing the accumulated
> + * runtime for this client, per engine class
> + */
> + for_each_gt(gt, xe, id_gt) {
> + xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
> + for_each_hw_engine(hwe, gt, id_hwe) {
> + const char *class_name;
> +
> + if (!capacity[hwe->class])
> + continue;
> +
> + /*
> + * Use any (first) engine to have a timestamp to be used every
> + * time
> + */
> + if (!gpu_stamp) {
> + gpu_timestamp = xe_hw_engine_read_timestamp(hwe);
> + gpu_stamp = true;
> + }
> +
> + class_name = xe_hw_engine_class_to_str(hwe->class);
> +
> + drm_printf(p, "drm-cycles-%s:\t%llu\n",
> + class_name, xef->runtime[hwe->class]);
> + drm_printf(p, "drm-total-cycles-%s:\t%llu\n",
> + class_name, gpu_timestamp);
> +
> + if (capacity[hwe->class] > 1)
> + drm_printf(p, "drm-engine-capacity-%s:\t%lu\n",
> + class_name, capacity[hwe->class]);
> +
> + /* engine class already handled, skip next iterations */
> + capacity[hwe->class] = 0;
> + }
> + xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
> + }
More FWIW and AFAICT, could just walk the "list" of classes instead of
the nested loop with skipping already visited classes. Assuming in xe
there is an easy way to get a known present engine for the gpu_timestamp
it would be flatter and less code.
Regards,
Tvrtko
> +
> + xe_pm_runtime_get(xe);
> +}
> +
> /**
> * xe_drm_client_fdinfo() - Callback for fdinfo interface
> * @p: The drm_printer ptr
> @@ -192,5 +327,6 @@ static void show_meminfo(struct drm_printer *p, struct drm_file *file)
> void xe_drm_client_fdinfo(struct drm_printer *p, struct drm_file *file)
> {
> show_meminfo(p, file);
> + show_runtime(p, file);
> }
> #endif
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