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[AMD Official Use Only - Internal Distribution Only]
The local variables need to be initialized to zero, since amdgpu_ctx_fence_time
accumulates and does not initialize
David
From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: Tuesday, May 11, 2021 12:53 AM To: Nieto, David M <David.Nieto@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> Subject: Re: [PATCH 2/2] drm/amdgpu: fix fence calculation Am 10.05.21 um 22:29 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@xxxxxxx> > Change-Id: I5b6e0ce5f489a5f55855d35354a6a3653e9d613b > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 13 ++++++++++++- > drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h | 1 + > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c > index 9036c93b4a0c..89ee464b9424 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c > @@ -698,16 +698,27 @@ ktime_t amdgpu_ctx_mgr_fence_usage(struct amdgpu_ctx_mgr *mgr, uint32_t hwip, > struct amdgpu_ctx_entity *centity; > ktime_t total = 0, max = 0; > > + Unrelated white space change. > if (idx >= AMDGPU_MAX_ENTITY_NUM) > return 0; > idp = &mgr->ctx_handles; > mutex_lock(&mgr->lock); > idr_for_each_entry(idp, ctx, id) { > + ktime_t ttotal = tmax = ktime_set(0, 0); There should be a blank line between decleration and code and please don't initialize local variables if it isn't necessary. Christian. > 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; |
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