From eff8cbf096a735116cf6fad94d795652d9e0ff41 Mon Sep 17 00:00:00 2001 From: Philip Yang Date: Sat, 31 Jul 2021 21:28:24 -0400 Subject: [PATCH] drm/amdkfd: AIP mGPUs best prefetch location for xnack on For xnack on, if range ACCESS or ACCESS_IN_PLACE (AIP) by single GPU, or range is ACCESS_IN_PLACE by mGPUs and all mGPUs connection on XGMI same hive, the best prefetch location is prefetch_loc GPU. Otherwise, the best prefetch location is always CPU because GPU does not have coherent mapping VRAM of other GPUs even with large-BAR PCIe connection. Signed-off-by: Philip Yang Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index 7df69b7..cffed40 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -2675,22 +2675,26 @@ svm_range_add(struct kfd_process *p, uint64_t start, uint64_t size, return 0; } -/* svm_range_best_prefetch_location - decide the best prefetch location +/** + * svm_range_best_prefetch_location - decide the best prefetch location * @prange: svm range structure * * For xnack off: - * If range map to single GPU, the best acutal location is prefetch loc, which + * If range map to single GPU, the best prefetch location is prefetch_loc, which * can be CPU or GPU. * - * If range map to multiple GPUs, only if mGPU connection on xgmi same hive, - * the best actual location could be prefetch_loc GPU. If mGPU connection on - * PCIe, the best actual location is always CPU, because GPU cannot access vram - * of other GPUs, assuming PCIe small bar (large bar support is not upstream). + * If range is ACCESS or ACCESS_IN_PLACE by mGPUs, only if mGPU connection on + * XGMI same hive, the best prefetch location is prefetch_loc GPU, othervise + * the best prefetch location is always CPU, because GPU can not have coherent + * mapping VRAM of other GPUs even with large-BAR PCIe connection. * * For xnack on: - * The best actual location is prefetch location. If mGPU connection on xgmi - * same hive, range map to multiple GPUs. Otherwise, the range only map to - * actual location GPU. Other GPU access vm fault will trigger migration. + * If range is not ACCESS_IN_PLACE by mGPUs, the best prefetch location is + * prefetch_loc, other GPU access will generate vm fault and trigger migration. + * + * If range is ACCESS_IN_PLACE by mGPUs, only if mGPU connection on XGMI same + * hive, the best prefetch location is prefetch_loc GPU, otherwise the best + * prefetch location is always CPU. * * Context: Process context * @@ -2710,11 +2714,6 @@ svm_range_best_prefetch_location(struct svm_range *prange) p = container_of(prange->svms, struct kfd_process, svms); - /* xnack on */ - if (p->xnack_enabled) - goto out; - - /* xnack off */ if (!best_loc || best_loc == KFD_IOCTL_SVM_LOCATION_UNDEFINED) goto out; @@ -2724,8 +2723,12 @@ svm_range_best_prefetch_location(struct svm_range *prange) best_loc = 0; goto out; } - bitmap_or(bitmap, prange->bitmap_access, prange->bitmap_aip, - MAX_GPU_INSTANCE); + + if (p->xnack_enabled) + bitmap_copy(bitmap, prange->bitmap_aip, MAX_GPU_INSTANCE); + else + bitmap_or(bitmap, prange->bitmap_access, prange->bitmap_aip, + MAX_GPU_INSTANCE); for_each_set_bit(gpuidx, bitmap, MAX_GPU_INSTANCE) { pdd = kfd_process_device_from_gpuidx(p, gpuidx); -- 2.7.4