Am 12.05.21 um 21:45 schrieb David M Nieto:
> The proper metric for fence utilization over several
> contexts is an harmonic mean, but such calculation is
> prohibitive in kernel space, so the code approximates it.
>
> Because the approximation diverges when one context has a
> very small ratio compared with the other context, this change
> filter out ratios smaller that 0.01%
>
> Signed-off-by: David M Nieto <david.nieto@amd.com>
> Change-Id: I5b6e0ce5f489a5f55855d35354a6a3653e9d613b

Looks good to me now, but the automated tools complain about "DOS line
endings" plus a couple of other nit picks and won't let me push it :)

Please use the checkpatch.pl script found in the Linux kernel to fix
those errors and resend.

Thanks,
Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 17 +++++++++++++++--
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h |  1 +
>   2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index 9036c93b4a0c..b919615e6644 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -652,12 +652,14 @@ void amdgpu_ctx_mgr_fini(struct amdgpu_ctx_mgr *mgr)
>        mutex_destroy(&mgr->lock);
>   }
>  
> -void amdgpu_ctx_fence_time(struct amdgpu_ctx *ctx, struct amdgpu_ctx_entity *centity,
> +static void amdgpu_ctx_fence_time(struct amdgpu_ctx *ctx, struct amdgpu_ctx_entity *centity,
>                ktime_t *total, ktime_t *max)
>   {
>        ktime_t now, t1;
>        uint32_t i;
>  
> +     *total = *max = 0;
> +
>        now = ktime_get();
>        for (i = 0; i < amdgpu_sched_jobs; i++) {
>                struct dma_fence *fence;
> @@ -703,11 +705,22 @@ ktime_t amdgpu_ctx_mgr_fence_usage(struct amdgpu_ctx_mgr *mgr, uint32_t hwip,
>        idp = &mgr->ctx_handles;
>        mutex_lock(&mgr->lock);
>        idr_for_each_entry(idp, ctx, id) {
> +             ktime_t ttotal, tmax;
> +
>                if (!ctx->entities[hwip][idx])
>                        continue;
>  
>                centity = ctx->entities[hwip][idx];
> -             amdgpu_ctx_fence_time(ctx, centity, &total, &max);
> +             amdgpu_ctx_fence_time(ctx, centity, &ttotal, &tmax);
> +
> +             /* Harmonic mean approximation diverges for very small
> +              * values. If ratio < 0.01% ignore
> +              */
> +             if (AMDGPU_CTX_FENCE_USAGE_MIN_RATIO(tmax, ttotal))
> +                     continue;
> +
> +             total = ktime_add(total, ttotal);
> +             max = ktime_after(tmax, max) ? tmax : max;
>        }
>  
>        mutex_unlock(&mgr->lock);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
> index 10dcf59a5c6b..3541dfb059ec 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h
> @@ -30,6 +30,7 @@ struct drm_file;
>   struct amdgpu_fpriv;
>  
>   #define AMDGPU_MAX_ENTITY_NUM 4
> +#define AMDGPU_CTX_FENCE_USAGE_MIN_RATIO(max, total) (max > 16384ULL*total)
>  
>   struct amdgpu_ctx_entity {
>        uint64_t                sequence;