[PATCH i-g-t] lib/intel_compute: use post-sync write to detect command level preemption
Zbigniew Kempczyński
zbigniew.kempczynski at intel.com
Wed Jul 2 07:32:43 UTC 2025
At command level when long job compute walker is finished we might
be immediately switched to short job. This defers signalling of long
job user-fence giving false impression this job is still ongoing.
Add post-sync write to compute walker to allow detect this situation
and fail if command level preemption occurred instead TG preemption.
Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Francois Dugast <francois.dugast at intel.com>
---
lib/intel_compute.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/lib/intel_compute.c b/lib/intel_compute.c
index 9f5fc1bc59..829d3a35f9 100644
--- a/lib/intel_compute.c
+++ b/lib/intel_compute.c
@@ -14,6 +14,7 @@
#include "gen8_media.h"
#include "gen9_media.h"
#include "intel_compute.h"
+#include "intel_mocs.h"
#include "lib/igt_syncobj.h"
#include "lib/intel_reg.h"
#include "xe/xe_ioctl.h"
@@ -52,6 +53,7 @@
#define OFFSET_STATE_SIP 0xFFFF0000
#define USER_FENCE_VALUE 0xdeadbeefdeadbeefull
+#define POST_SYNC_VALUE 0xabcdabcdcdefcdefull
#define MAGIC_LOOP_STOP 0x12341234
#define THREADS_PER_GROUP 32
@@ -60,6 +62,9 @@
#define ENQUEUED_LOCAL_SIZE_X 1024
#define ENQUEUED_LOCAL_SIZE_Y 1
#define ENQUEUED_LOCAL_SIZE_Z 1
+#define DP_SS_CACHE_FLUSH (1 << 12)
+#define DP_PIPELINE_FLUSH (1 << 2)
+#define WRITE_IMM_DATA (1 << 0)
/*
* TGP - ThreadGroup Preemption
@@ -1532,7 +1537,8 @@ static void xelpg_compute_exec_compute(uint32_t *addr_bo_buffer_batch,
addr_bo_buffer_batch[b++] = MI_BATCH_BUFFER_END;
}
-static void xe2lpg_compute_exec_compute(uint32_t *addr_bo_buffer_batch,
+static void xe2lpg_compute_exec_compute(int fd,
+ uint32_t *addr_bo_buffer_batch,
uint64_t addr_general_state_base,
uint64_t addr_surface_state_base,
uint64_t addr_dynamic_state_base,
@@ -1544,6 +1550,7 @@ static void xe2lpg_compute_exec_compute(uint32_t *addr_bo_buffer_batch,
bool threadgroup_preemption,
uint32_t work_size)
{
+ uint8_t uc_mocs = intel_get_uc_mocs_index(fd);
int b = 0;
igt_debug("general state base: %"PRIx64"\n", addr_general_state_base);
@@ -1603,7 +1610,7 @@ static void xe2lpg_compute_exec_compute(uint32_t *addr_bo_buffer_batch,
addr_bo_buffer_batch[b++] = addr_surface_state_base >> 32;
addr_bo_buffer_batch[b++] = 0x001ff000;
- if (sip_start_pointer) {
+ if (sip_start_pointer && !threadgroup_preemption) {
addr_bo_buffer_batch[b++] = XE2_STATE_SIP | 0x1;
addr_bo_buffer_batch[b++] = sip_start_pointer;
addr_bo_buffer_batch[b++] = 0x00000000;
@@ -1651,11 +1658,12 @@ static void xe2lpg_compute_exec_compute(uint32_t *addr_bo_buffer_batch,
addr_bo_buffer_batch[b++] = 0x0c000000 | THREADS_PER_GROUP;
addr_bo_buffer_batch[b++] = 0x00000000;
addr_bo_buffer_batch[b++] = 0x00000000;
- addr_bo_buffer_batch[b++] = 0x00001047;
+ addr_bo_buffer_batch[b++] = DP_SS_CACHE_FLUSH | uc_mocs << 4 |
+ DP_PIPELINE_FLUSH | WRITE_IMM_DATA;
addr_bo_buffer_batch[b++] = ADDR_BATCH;
addr_bo_buffer_batch[b++] = ADDR_BATCH >> 32;
- addr_bo_buffer_batch[b++] = 0x00000000;
- addr_bo_buffer_batch[b++] = 0x00000000;
+ addr_bo_buffer_batch[b++] = (uint32_t) POST_SYNC_VALUE;
+ addr_bo_buffer_batch[b++] = (uint32_t) (POST_SYNC_VALUE >> 32);
addr_bo_buffer_batch[b++] = 0x00000000;
addr_bo_buffer_batch[b++] = 0x00000000;
addr_bo_buffer_batch[b++] = 0x00000000;
@@ -1857,7 +1865,8 @@ static void xe2lpg_compute_exec(int fd, const unsigned char *kernel,
input_data = get_input_data(&execenv, user, bo_dict[4].data);
output_data = get_output_data(&execenv, user, bo_dict[5].data);
- xe2lpg_compute_exec_compute(bo_dict[8].data,
+ xe2lpg_compute_exec_compute(fd,
+ bo_dict[8].data,
ADDR_GENERAL_STATE_BASE,
ADDR_SURFACE_STATE_BASE,
ADDR_DYNAMIC_STATE_BASE,
@@ -2101,6 +2110,7 @@ static void xe2lpg_compute_preempt_exec(int fd, const unsigned char *long_kernel
struct bo_dict_entry bo_dict_short[ARRAY_SIZE(bo_dict_long)];
struct bo_execenv execenv_short, execenv_long;
float *input_short, *output_short, *input_long;
+ uint64_t *post_data;
unsigned int long_kernel_loop_count = 0;
int64_t timeout_one_ns = 1;
bool use_loop_kernel = loop_kernel && !threadgroup_preemption;
@@ -2149,16 +2159,19 @@ static void xe2lpg_compute_preempt_exec(int fd, const unsigned char *long_kernel
input_long = (float *) bo_dict_long[4].data;
input_short = (float *) bo_dict_short[4].data;
output_short = (float *) bo_dict_short[5].data;
+ post_data = (uint64_t *) bo_dict_long[8].data;
bo_randomize(input_short, SIZE_DATA);
- xe2lpg_compute_exec_compute(bo_dict_long[8].data, ADDR_GENERAL_STATE_BASE,
+ xe2lpg_compute_exec_compute(fd,
+ bo_dict_long[8].data, ADDR_GENERAL_STATE_BASE,
ADDR_SURFACE_STATE_BASE, ADDR_DYNAMIC_STATE_BASE,
ADDR_INSTRUCTION_STATE_BASE, XE2_ADDR_STATE_CONTEXT_DATA_BASE,
OFFSET_INDIRECT_DATA_START, OFFSET_KERNEL, OFFSET_STATE_SIP,
threadgroup_preemption, SIZE_DATA);
- xe2lpg_compute_exec_compute(bo_dict_short[8].data, ADDR_GENERAL_STATE_BASE,
+ xe2lpg_compute_exec_compute(fd,
+ bo_dict_short[8].data, ADDR_GENERAL_STATE_BASE,
ADDR_SURFACE_STATE_BASE, ADDR_DYNAMIC_STATE_BASE,
ADDR_INSTRUCTION_STATE_BASE, XE2_ADDR_STATE_CONTEXT_DATA_BASE,
OFFSET_INDIRECT_DATA_START, OFFSET_KERNEL, OFFSET_STATE_SIP,
@@ -2177,6 +2190,12 @@ static void xe2lpg_compute_preempt_exec(int fd, const unsigned char *long_kernel
bo_execenv_exec(&execenv_short, ADDR_BATCH);
bo_check_square(input_short, output_short, SIZE_DATA);
+ /*
+ * Catch command level preemption instead TG preemption. For TG and WMTP
+ * post sync can't be visible at this point yet.
+ */
+ igt_assert_neq_u64(POST_SYNC_VALUE, *post_data);
+
/* Check that the long kernel has not completed yet */
igt_assert_neq(0, __xe_wait_ufence(fd, &execenv_long.bo_sync->sync, USER_FENCE_VALUE,
execenv_long.exec_queue, &timeout_one_ns));
@@ -2187,6 +2206,7 @@ static void xe2lpg_compute_preempt_exec(int fd, const unsigned char *long_kernel
((int *)input_long)[0] = MAGIC_LOOP_STOP;
bo_execenv_sync(&execenv_long);
+ igt_assert_eq_u64(POST_SYNC_VALUE, *post_data);
bo_execenv_unbind(&execenv_short, bo_dict_short, entries);
bo_execenv_unbind(&execenv_long, bo_dict_long, entries);
--
2.43.0
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