From 303b446f2e8f9cdebc822f1f72af385374d17d37 Mon Sep 17 00:00:00 2001 From: Matthew Brost Date: Wed, 14 Jan 2026 16:45:46 -0800 Subject: [PATCH] drm/xe: Do not preempt fence signaling CS instructions [ Upstream commit cdc8a1e11f4d5b480ec750e28010c357185b95a6 ] If a batch buffer is complete, it makes little sense to preempt the fence signaling instructions in the ring, as the largest portion of the work (the batch buffer) is already done and fence signaling consists of only a few instructions. If these instructions are preempted, the GuC would need to perform a context switch just to signal the fence, which is costly and delays fence signaling. Avoid this scenario by disabling preemption immediately after the BB start instruction and re-enabling it after executing the fence signaling instructions. Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Cc: Daniele Ceraolo Spurio Cc: Carlos Santa Signed-off-by: Matthew Brost Reviewed-by: Daniele Ceraolo Spurio Link: https://patch.msgid.link/20260115004546.58060-1-matthew.brost@intel.com (cherry picked from commit 2bcbf2dcde0c839a73af664a3c77d4e77d58a3eb) Signed-off-by: Rodrigo Vivi Signed-off-by: Sasha Levin --- drivers/gpu/drm/xe/xe_ring_ops.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/xe/xe_ring_ops.c b/drivers/gpu/drm/xe/xe_ring_ops.c index d71837773d6c..e0082b55e216 100644 --- a/drivers/gpu/drm/xe/xe_ring_ops.c +++ b/drivers/gpu/drm/xe/xe_ring_ops.c @@ -265,6 +265,9 @@ static void __emit_job_gen12_simple(struct xe_sched_job *job, struct xe_lrc *lrc i = emit_bb_start(batch_addr, ppgtt_flag, dw, i); + /* Don't preempt fence signaling */ + dw[i++] = MI_ARB_ON_OFF | MI_ARB_DISABLE; + if (job->user_fence.used) { i = emit_flush_dw(dw, i); i = emit_store_imm_ppgtt_posted(job->user_fence.addr, @@ -328,6 +331,9 @@ static void __emit_job_gen12_video(struct xe_sched_job *job, struct xe_lrc *lrc, i = emit_bb_start(batch_addr, ppgtt_flag, dw, i); + /* Don't preempt fence signaling */ + dw[i++] = MI_ARB_ON_OFF | MI_ARB_DISABLE; + if (job->user_fence.used) { i = emit_flush_dw(dw, i); i = emit_store_imm_ppgtt_posted(job->user_fence.addr, @@ -377,6 +383,9 @@ static void __emit_job_gen12_render_compute(struct xe_sched_job *job, i = emit_bb_start(batch_addr, ppgtt_flag, dw, i); + /* Don't preempt fence signaling */ + dw[i++] = MI_ARB_ON_OFF | MI_ARB_DISABLE; + i = emit_render_cache_flush(job, dw, i); if (job->user_fence.used)