Re: [PATCH 2/2] drm/amdgpu: add shared fdinfo stats

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Am 09.01.24 um 15:26 schrieb Daniel Vetter:
On Tue, 9 Jan 2024 at 14:25, Tvrtko Ursulin
<tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:

On 09/01/2024 12:54, Daniel Vetter wrote:
On Tue, Jan 09, 2024 at 09:30:15AM +0000, Tvrtko Ursulin wrote:
On 09/01/2024 07:56, Christian König wrote:
Am 07.12.23 um 19:02 schrieb Alex Deucher:
Add shared stats.  Useful for seeing shared memory.

v2: take dma-buf into account as well

Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
---
    drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c |  4 ++++
    drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 +++++++++++
    drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  6 ++++++
    3 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
index 5706b282a0c7..c7df7fa3459f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c
@@ -97,6 +97,10 @@ void amdgpu_show_fdinfo(struct drm_printer *p,
struct drm_file *file)
               stats.requested_visible_vram/1024UL);
        drm_printf(p, "amd-requested-gtt:\t%llu KiB\n",
               stats.requested_gtt/1024UL);
+    drm_printf(p, "drm-shared-vram:\t%llu KiB\n",
stats.vram_shared/1024UL);
+    drm_printf(p, "drm-shared-gtt:\t%llu KiB\n",
stats.gtt_shared/1024UL);
+    drm_printf(p, "drm-shared-cpu:\t%llu KiB\n",
stats.cpu_shared/1024UL);
+
        for (hw_ip = 0; hw_ip < AMDGPU_HW_IP_NUM; ++hw_ip) {
            if (!usage[hw_ip])
                continue;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index d79b4ca1ecfc..1b37d95475b8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -1287,25 +1287,36 @@ void amdgpu_bo_get_memory(struct amdgpu_bo *bo,
                  struct amdgpu_mem_stats *stats)
    {
        uint64_t size = amdgpu_bo_size(bo);
+    struct drm_gem_object *obj;
        unsigned int domain;
+    bool shared;
        /* Abort if the BO doesn't currently have a backing store */
        if (!bo->tbo.resource)
            return;
+    obj = &bo->tbo.base;
+    shared = (obj->handle_count > 1) || obj->dma_buf;
I still think that looking at handle_count is the completely wrong
approach, we should really only look at obj->dma_buf.
Yeah it is all a bit tricky with the handle table walk. I don't think it is
even possible to claim it is shared with obj->dma_buf could be the same
process creating say via udmabuf and importing into drm. It is a wild
scenario yes, but it could be private memory in that case. Not sure where it
would leave us if we said this is just a limitation of a BO based tracking.

Would adding a new category "imported" help?

Hmm or we simply change drm-usage-stats.rst:

"""
- drm-shared-<region>: <uint> [KiB|MiB]

The total size of buffers that are shared with another file (ie. have more
than than a single handle).
"""

Changing ie into eg coule be get our of jail free card to allow the
"(obj->handle_count > 1) || obj->dma_buf;" condition?

Because of the shared with another _file_ wording would cover my wild
udmabuf self-import case. Unless there are more such creative private import
options.
Yeah I think clarifying that we can only track sharing with other fd and
have no idea whether this means sharing with another process or not is
probably simplest. Maybe not exactly what users want, but still the
roughly best-case approximation we can deliver somewhat cheaply.

Also maybe time for a drm_gem_buffer_object_is_shared() helper so we don't
copypaste this all over and then end up in divergent conditions? I'm
guessing that there's going to be a bunch of drivers which needs this
little helper to add drm-shared-* stats to their fdinfo ...
Yeah I agree that works and i915 would need to use the helper too.

I would only suggest to name it so the meaning of shared is obviously
only about the fdinfo memory stats and no one gets a more meaningful
idea about its semantics.

We have drm_show_memory_stats and drm_print_memory_stats exported so
perhaps something like drm_object_is_shared_for_memory_stats,
drm_object_is_memory_stats_shared, drm_memory_stats_object_is_shared?

+ for drm_object_is_shared_for_memory_stats().


And s/ie/eg/ in the above quoted drm-usage-stats.rst.
Ack on making it clear this helper would be for fdinfo memory stats
only. Sounds like a good idea to stop people from finding really
creative uses ...

It's astonishing how defensive the development process has become :)

Cheers,
Christian.

-Sima

Regards,

Tvrtko

Cheers, Sima
Regards,

Tvrtko

Regards,
Christian.

+
        domain = amdgpu_mem_type_to_domain(bo->tbo.resource->mem_type);
        switch (domain) {
        case AMDGPU_GEM_DOMAIN_VRAM:
            stats->vram += size;
            if (amdgpu_bo_in_cpu_visible_vram(bo))
                stats->visible_vram += size;
+        if (shared)
+            stats->vram_shared += size;
            break;
        case AMDGPU_GEM_DOMAIN_GTT:
            stats->gtt += size;
+        if (shared)
+            stats->gtt_shared += size;
            break;
        case AMDGPU_GEM_DOMAIN_CPU:
        default:
            stats->cpu += size;
+        if (shared)
+            stats->cpu_shared += size;
            break;
        }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
index d28e21baef16..0503af75dc26 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
@@ -138,12 +138,18 @@ struct amdgpu_bo_vm {
    struct amdgpu_mem_stats {
        /* current VRAM usage, includes visible VRAM */
        uint64_t vram;
+    /* current shared VRAM usage, includes visible VRAM */
+    uint64_t vram_shared;
        /* current visible VRAM usage */
        uint64_t visible_vram;
        /* current GTT usage */
        uint64_t gtt;
+    /* current shared GTT usage */
+    uint64_t gtt_shared;
        /* current system memory usage */
        uint64_t cpu;
+    /* current shared system memory usage */
+    uint64_t cpu_shared;
        /* sum of evicted buffers, includes visible VRAM */
        uint64_t evicted_vram;
        /* sum of evicted buffers due to CPU access */






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