[v4,1/3] lib: add igt_dummyload

Commit Message

Abdiel Janulgue Nov. 7, 2016, 7:48 a.m. UTC

A lot of igt testcases need some GPU workload to make sure a race
window is big enough. Unfortunately having a fixed amount of
workload leads to spurious test failures or overtly long runtimes
on some fast/slow platforms. This library contains functionality
to submit GPU workloads that should consume exactly a specific
amount of time.

v2 : Add recursive batch feature from Chris
v3 : Drop auto-tuned stuff. Add bo dependecy to recursive batch
     by adding a dummy reloc to the bo as suggested by Ville.
v4:  Fix dependency reloc as write instead of read (Ville).
     Fix wrong handling of batchbuffer start on ILK causing
     test failure

Cc: Daniel Vetter <[e-mail]>
Cc: Ville Syrjälä <[e-mail]>
Cc: Chris Wilson <[e-mail]>
Signed-off-by: Abdiel Janulgue <[e-mail]>
---
 lib/Makefile.sources |   2 +
 lib/igt.h            |   1 +
 lib/igt_dummyload.c  | 274 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_dummyload.h  |  42 ++++++++
 4 files changed, 319 insertions(+)
 create mode 100644 lib/igt_dummyload.c
 create mode 100644 lib/igt_dummyload.h

Comments

Abdiel Janulgue Nov. 8, 2016, 11:50 a.m. UTC | #1

By the way, series was tested on CI with no regressions.

- Abdiel

On 11/07/2016 09:48 AM, Abdiel Janulgue wrote:
> A lot of igt testcases need some GPU workload to make sure a race
> window is big enough. Unfortunately having a fixed amount of
> workload leads to spurious test failures or overtly long runtimes
> on some fast/slow platforms. This library contains functionality
> to submit GPU workloads that should consume exactly a specific
> amount of time.
> 
> v2 : Add recursive batch feature from Chris
> v3 : Drop auto-tuned stuff. Add bo dependecy to recursive batch
>      by adding a dummy reloc to the bo as suggested by Ville.
> v4:  Fix dependency reloc as write instead of read (Ville).
>      Fix wrong handling of batchbuffer start on ILK causing
>      test failure
> 
> Cc: Daniel Vetter <[e-mail]>
> Cc: Ville Syrjälä <[e-mail]>
> Cc: Chris Wilson <[e-mail]>
> Signed-off-by: Abdiel Janulgue <[e-mail]>
> ---
>  lib/Makefile.sources |   2 +
>  lib/igt.h            |   1 +
>  lib/igt_dummyload.c  | 274 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  lib/igt_dummyload.h  |  42 ++++++++
>  4 files changed, 319 insertions(+)
>  create mode 100644 lib/igt_dummyload.c
>  create mode 100644 lib/igt_dummyload.h
> 
> diff --git a/lib/Makefile.sources b/lib/Makefile.sources
> index e8e277b..7fc5ec2 100644
> --- a/lib/Makefile.sources
> +++ b/lib/Makefile.sources
> @@ -75,6 +75,8 @@ lib_source_list =	 	\
>  	igt_draw.h		\
>  	igt_pm.c		\
>  	igt_pm.h		\
> +	igt_dummyload.c		\
> +	igt_dummyload.h		\
>  	uwildmat/uwildmat.h	\
>  	uwildmat/uwildmat.c	\
>  	$(NULL)
> diff --git a/lib/igt.h b/lib/igt.h
> index d751f24..a0028d5 100644
> --- a/lib/igt.h
> +++ b/lib/igt.h
> @@ -32,6 +32,7 @@
>  #include "igt_core.h"
>  #include "igt_debugfs.h"
>  #include "igt_draw.h"
> +#include "igt_dummyload.h"
>  #include "igt_fb.h"
>  #include "igt_gt.h"
>  #include "igt_kms.h"
> diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
> new file mode 100644
> index 0000000..2d05594
> --- /dev/null
> +++ b/lib/igt_dummyload.c
> @@ -0,0 +1,274 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + */
> +
> +#include "igt.h"
> +#include "igt_dummyload.h"
> +#include <time.h>
> +#include <signal.h>
> +#include <sys/syscall.h>
> +
> +/**
> + * SECTION:igt_dummyload
> + * @short_description: Library for submitting GPU workloads
> + * @title: Dummyload
> + * @include: igt.h
> + *
> + * A lot of igt testcases need some GPU workload to make sure a race window is
> + * big enough. Unfortunately having a fixed amount of workload leads to
> + * spurious test failures or overtly long runtimes on some fast/slow platforms.
> + * This library contains functionality to submit GPU workloads that should
> + * consume exactly a specific amount of time.
> + */
> +
> +#define NSEC_PER_SEC 1000000000L
> +
> +#define gettid() syscall(__NR_gettid)
> +#define sigev_notify_thread_id _sigev_un._tid
> +
> +#define LOCAL_I915_EXEC_BSD_SHIFT      (13)
> +#define LOCAL_I915_EXEC_BSD_MASK       (3 << LOCAL_I915_EXEC_BSD_SHIFT)
> +
> +#define ENGINE_MASK  (I915_EXEC_RING_MASK | LOCAL_I915_EXEC_BSD_MASK)
> +
> +static void
> +fill_object(struct drm_i915_gem_exec_object2 *obj, uint32_t gem_handle,
> +	    struct drm_i915_gem_relocation_entry *relocs, uint32_t count)
> +{
> +	memset(obj, 0, sizeof(*obj));
> +	obj->handle = gem_handle;
> +	obj->relocation_count = count;
> +	obj->relocs_ptr = (uintptr_t)relocs;
> +}
> +
> +static void
> +fill_reloc(struct drm_i915_gem_relocation_entry *reloc,
> +	   uint32_t gem_handle, uint32_t offset,
> +	   uint32_t read_domains, uint32_t write_domains)
> +{
> +	reloc->target_handle = gem_handle;
> +	reloc->delta = 0;
> +	reloc->offset = offset * sizeof(uint32_t);
> +	reloc->presumed_offset = 0;
> +	reloc->read_domains = read_domains;
> +	reloc->write_domain = write_domains;
> +}
> +
> +
> +static uint32_t *batch;
> +
> +static uint32_t emit_recursive_batch(int fd, int engine, unsigned dep_handle)
> +{
> +	const int gen = intel_gen(intel_get_drm_devid(fd));
> +	struct drm_i915_gem_exec_object2 obj[2];
> +	struct drm_i915_gem_relocation_entry relocs[2];
> +	struct drm_i915_gem_execbuffer2 execbuf;
> +	unsigned engines[16];
> +	unsigned nengine, handle;
> +	int i = 0, reloc_count = 0, buf_count = 0;
> +
> +	buf_count = 0;
> +	nengine = 0;
> +	if (engine < 0) {
> +		for_each_engine(fd, engine)
> +			if (engine)
> +				engines[nengine++] = engine;
> +	} else {
> +		igt_require(gem_has_ring(fd, engine));
> +		engines[nengine++] = engine;
> +	}
> +	igt_require(nengine);
> +
> +	memset(&execbuf, 0, sizeof(execbuf));
> +	memset(obj, 0, sizeof(obj));
> +	memset(relocs, 0, sizeof(relocs));
> +
> +	execbuf.buffers_ptr = (uintptr_t) obj;
> +	handle = gem_create(fd, 4096);
> +	batch = gem_mmap__gtt(fd, handle, 4096, PROT_WRITE);
> +	gem_set_domain(fd, handle,
> +			I915_GEM_DOMAIN_GTT, I915_GEM_DOMAIN_GTT);
> +
> +	if (dep_handle > 0) {
> +		fill_object(&obj[buf_count], dep_handle, NULL, 0);
> +		buf_count++;
> +
> +		fill_reloc(&relocs[reloc_count], dep_handle, i, 0,
> +			   I915_GEM_DOMAIN_COMMAND);
> +		batch[i++] = 0; /* reloc */
> +		reloc_count++;
> +		batch[i++] = MI_NOOP;
> +	}
> +
> +	if (gen >= 8) {
> +		batch[i++] = MI_BATCH_BUFFER_START | 1 << 8 | 1;
> +		/* recurse */
> +		fill_reloc(&relocs[reloc_count], handle, i,
> +			   I915_GEM_DOMAIN_COMMAND, 0);
> +		batch[i++] = 0;
> +		batch[i++] = 0;
> +	} else if (gen >= 6) {
> +		batch[i++] = MI_BATCH_BUFFER_START | 1 << 8;
> +		/* recurse */
> +		fill_reloc(&relocs[reloc_count], handle, i,
> +			   I915_GEM_DOMAIN_COMMAND, 0);
> +		batch[i++] = 0;
> +	} else {
> +		batch[i++] = MI_BATCH_BUFFER_START | 2 << 6 |
> +			((gen < 4) ? 1 : 0);
> +		/* recurse */
> +		fill_reloc(&relocs[reloc_count], handle, i,
> +			   I915_GEM_DOMAIN_COMMAND, 0);
> +		batch[i++] = 0;
> +		if (gen < 4)
> +			relocs[reloc_count].delta = 1;
> +	}
> +	reloc_count++;
> +
> +	fill_object(&obj[buf_count], handle, relocs, reloc_count);
> +	buf_count++;
> +
> +	for (i = 0; i < nengine; i++) {
> +		execbuf.flags &= ~ENGINE_MASK;
> +		execbuf.flags = engines[i];
> +		execbuf.buffer_count = buf_count;
> +		gem_execbuf(fd, &execbuf);
> +	}
> +
> +	return handle;
> +}
> +
> +static void sigiter(int sig, siginfo_t *info, void *arg)
> +{
> +	*batch = MI_BATCH_BUFFER_END;
> +	__sync_synchronize();
> +}
> +
> +static timer_t setup_batch_exit_timer(int64_t ns)
> +{
> +	timer_t timer;
> +	struct sigevent sev;
> +	struct sigaction act;
> +	struct itimerspec its;
> +
> +	memset(&sev, 0, sizeof(sev));
> +	sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
> +	sev.sigev_notify_thread_id = gettid();
> +	sev.sigev_signo = SIGRTMIN + 1;
> +	igt_assert(timer_create(CLOCK_MONOTONIC, &sev, &timer) == 0);
> +	igt_assert(timer > 0);
> +
> +	memset(&act, 0, sizeof(act));
> +	act.sa_sigaction = sigiter;
> +	act.sa_flags = SA_SIGINFO;
> +	igt_assert(sigaction(SIGRTMIN + 1, &act, NULL) == 0);
> +
> +	memset(&its, 0, sizeof(its));
> +	its.it_value.tv_sec = ns / NSEC_PER_SEC;
> +	its.it_value.tv_nsec = ns % NSEC_PER_SEC;
> +	igt_assert(timer_settime(timer, 0, &its, NULL) == 0);
> +
> +	return timer;
> +}
> +
> +/**
> + * igt_spin_batch:
> + * @fd: open i915 drm file descriptor
> + * @ns: amount of time in nanoseconds the batch executes after terminating.
> + *      If value is less than 0, execute batch forever.
> + * @engine: Ring to execute batch OR'd with execbuf flags. If value is less
> + *          than 0, execute on all available rings.
> + * @dep_handle: handle to a buffer object dependency. If greater than 0, add a
> + *              relocation entry to this buffer within the batch.
> + *
> + * Start a recursive batch on a ring that terminates after an exact amount
> + * of time has elapsed. Immediately returns a #igt_spin_t that contains the
> + * batch's handle that can be waited upon. The returned structure must be passed to
> + * igt_post_spin_batch() for post-processing.
> + *
> + * Returns:
> + * Structure with helper internal state for igt_post_spin_batch().
> + */
> +igt_spin_t igt_spin_batch(int fd, int64_t ns, int engine, unsigned dep_handle)
> +{
> +	timer_t timer;
> +	uint32_t handle = emit_recursive_batch(fd, engine, dep_handle);
> +	int64_t wait_timeout = 0;
> +	igt_assert_eq(gem_wait(fd, handle, &wait_timeout), -ETIME);
> +
> +	if (ns < 1) {
> +		if (ns == 0) {
> +			*batch = MI_BATCH_BUFFER_END;
> +			__sync_synchronize();
> +			return (igt_spin_t){ handle, batch, 0};
> +		}
> +		return (igt_spin_t){ handle, batch, 0 };
> +	}
> +	timer = setup_batch_exit_timer(ns);
> +
> +	return (igt_spin_t){ handle, batch, timer };
> +}
> +
> +/**
> + * igt_post_spin_batch:
> + * @fd: open i915 drm file descriptor
> + * @arg: spin batch state from igt_spin_batch()
> + *
> + * This function does the necessary post-processing after starting a recursive
> + * batch with igt_spin_batch().
> + */
> +void igt_post_spin_batch(int fd, igt_spin_t arg)
> +{
> +	if (arg.handle == 0)
> +		return;
> +
> +	if (arg.timer > 0)
> +		timer_delete(arg.timer);
> +
> +	gem_close(fd, arg.handle);
> +	munmap(arg.batch, 4096);
> +}
> +
> +
> +/**
> + * igt_spin_batch_wait:
> + * @fd: open i915 drm file descriptor
> + * @ns: amount of time in nanoseconds the batch executes after terminating.
> + *      If value is less than 0, execute batch forever.
> + * @engine: ring to execute batch OR'd with execbuf flags. If value is less
> + *          than 0, execute on all available rings.
> + * @dep_handle: handle to a buffer object dependency. If greater than 0, include
> + *              this buffer on the wait dependency
> + *
> + * This is similar to igt_spin_batch(), but waits on the recursive batch to finish
> + * instead of returning right away. The function also does the necessary
> + * post-processing automatically if set to timeout.
> + */
> +void igt_spin_batch_wait(int fd, int64_t ns, int engine, unsigned dep_handle)
> +{
> +	igt_spin_t spin = igt_spin_batch(fd, ns, engine, dep_handle);
> +	int64_t wait_timeout = ns + (0.5 * NSEC_PER_SEC);
> +	igt_assert_eq(gem_wait(fd, spin.handle, &wait_timeout), 0);
> +
> +	igt_post_spin_batch(fd, spin);
> +}
> diff --git a/lib/igt_dummyload.h b/lib/igt_dummyload.h
> new file mode 100644
> index 0000000..79ead2c
> --- /dev/null
> +++ b/lib/igt_dummyload.h
> @@ -0,0 +1,42 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + */
> +
> +#ifndef __IGT_DUMMYLOAD_H__
> +#define __IGT_DUMMYLOAD_H__
> +
> +typedef struct igt_spin {
> +	unsigned handle;
> +	uint32_t *batch;
> +	timer_t timer;
> +} igt_spin_t;
> +
> +
> +igt_spin_t igt_spin_batch(int fd, int64_t ns, int engine, unsigned dep_handle);
> +
> +void igt_post_spin_batch(int fd, igt_spin_t arg);
> +
> +void igt_spin_batch_wait(int fd, int64_t ns, int engine, unsigned dep_handle);
> +
> +
> +#endif /* __IGT_DUMMYLOAD_H__ */
>

Patch

diff --git a/lib/Makefile.sources b/lib/Makefile.sources
index e8e277b..7fc5ec2 100644
--- a/lib/Makefile.sources
+++ b/lib/Makefile.sources
@@ -75,6 +75,8 @@  lib_source_list =	 	\
 	igt_draw.h		\
 	igt_pm.c		\
 	igt_pm.h		\
+	igt_dummyload.c		\
+	igt_dummyload.h		\
 	uwildmat/uwildmat.h	\
 	uwildmat/uwildmat.c	\
 	$(NULL)
diff --git a/lib/igt.h b/lib/igt.h
index d751f24..a0028d5 100644
--- a/lib/igt.h
+++ b/lib/igt.h
@@ -32,6 +32,7 @@ 
 #include "igt_core.h"
 #include "igt_debugfs.h"
 #include "igt_draw.h"
+#include "igt_dummyload.h"
 #include "igt_fb.h"
 #include "igt_gt.h"
 #include "igt_kms.h"
diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
new file mode 100644
index 0000000..2d05594
--- /dev/null
+++ b/lib/igt_dummyload.c
@@ -0,0 +1,274 @@ 
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include "igt.h"
+#include "igt_dummyload.h"
+#include <time.h>
+#include <signal.h>
+#include <sys/syscall.h>
+
+/**
+ * SECTION:igt_dummyload
+ * @short_description: Library for submitting GPU workloads
+ * @title: Dummyload
+ * @include: igt.h
+ *
+ * A lot of igt testcases need some GPU workload to make sure a race window is
+ * big enough. Unfortunately having a fixed amount of workload leads to
+ * spurious test failures or overtly long runtimes on some fast/slow platforms.
+ * This library contains functionality to submit GPU workloads that should
+ * consume exactly a specific amount of time.
+ */
+
+#define NSEC_PER_SEC 1000000000L
+
+#define gettid() syscall(__NR_gettid)
+#define sigev_notify_thread_id _sigev_un._tid
+
+#define LOCAL_I915_EXEC_BSD_SHIFT      (13)
+#define LOCAL_I915_EXEC_BSD_MASK       (3 << LOCAL_I915_EXEC_BSD_SHIFT)
+
+#define ENGINE_MASK  (I915_EXEC_RING_MASK | LOCAL_I915_EXEC_BSD_MASK)
+
+static void
+fill_object(struct drm_i915_gem_exec_object2 *obj, uint32_t gem_handle,
+	    struct drm_i915_gem_relocation_entry *relocs, uint32_t count)
+{
+	memset(obj, 0, sizeof(*obj));
+	obj->handle = gem_handle;
+	obj->relocation_count = count;
+	obj->relocs_ptr = (uintptr_t)relocs;
+}
+
+static void
+fill_reloc(struct drm_i915_gem_relocation_entry *reloc,
+	   uint32_t gem_handle, uint32_t offset,
+	   uint32_t read_domains, uint32_t write_domains)
+{
+	reloc->target_handle = gem_handle;
+	reloc->delta = 0;
+	reloc->offset = offset * sizeof(uint32_t);
+	reloc->presumed_offset = 0;
+	reloc->read_domains = read_domains;
+	reloc->write_domain = write_domains;
+}
+
+
+static uint32_t *batch;
+
+static uint32_t emit_recursive_batch(int fd, int engine, unsigned dep_handle)
+{
+	const int gen = intel_gen(intel_get_drm_devid(fd));
+	struct drm_i915_gem_exec_object2 obj[2];
+	struct drm_i915_gem_relocation_entry relocs[2];
+	struct drm_i915_gem_execbuffer2 execbuf;
+	unsigned engines[16];
+	unsigned nengine, handle;
+	int i = 0, reloc_count = 0, buf_count = 0;
+
+	buf_count = 0;
+	nengine = 0;
+	if (engine < 0) {
+		for_each_engine(fd, engine)
+			if (engine)
+				engines[nengine++] = engine;
+	} else {
+		igt_require(gem_has_ring(fd, engine));
+		engines[nengine++] = engine;
+	}
+	igt_require(nengine);
+
+	memset(&execbuf, 0, sizeof(execbuf));
+	memset(obj, 0, sizeof(obj));
+	memset(relocs, 0, sizeof(relocs));
+
+	execbuf.buffers_ptr = (uintptr_t) obj;
+	handle = gem_create(fd, 4096);
+	batch = gem_mmap__gtt(fd, handle, 4096, PROT_WRITE);
+	gem_set_domain(fd, handle,
+			I915_GEM_DOMAIN_GTT, I915_GEM_DOMAIN_GTT);
+
+	if (dep_handle > 0) {
+		fill_object(&obj[buf_count], dep_handle, NULL, 0);
+		buf_count++;
+
+		fill_reloc(&relocs[reloc_count], dep_handle, i, 0,
+			   I915_GEM_DOMAIN_COMMAND);
+		batch[i++] = 0; /* reloc */
+		reloc_count++;
+		batch[i++] = MI_NOOP;
+	}
+
+	if (gen >= 8) {
+		batch[i++] = MI_BATCH_BUFFER_START | 1 << 8 | 1;
+		/* recurse */
+		fill_reloc(&relocs[reloc_count], handle, i,
+			   I915_GEM_DOMAIN_COMMAND, 0);
+		batch[i++] = 0;
+		batch[i++] = 0;
+	} else if (gen >= 6) {
+		batch[i++] = MI_BATCH_BUFFER_START | 1 << 8;
+		/* recurse */
+		fill_reloc(&relocs[reloc_count], handle, i,
+			   I915_GEM_DOMAIN_COMMAND, 0);
+		batch[i++] = 0;
+	} else {
+		batch[i++] = MI_BATCH_BUFFER_START | 2 << 6 |
+			((gen < 4) ? 1 : 0);
+		/* recurse */
+		fill_reloc(&relocs[reloc_count], handle, i,
+			   I915_GEM_DOMAIN_COMMAND, 0);
+		batch[i++] = 0;
+		if (gen < 4)
+			relocs[reloc_count].delta = 1;
+	}
+	reloc_count++;
+
+	fill_object(&obj[buf_count], handle, relocs, reloc_count);
+	buf_count++;
+
+	for (i = 0; i < nengine; i++) {
+		execbuf.flags &= ~ENGINE_MASK;
+		execbuf.flags = engines[i];
+		execbuf.buffer_count = buf_count;
+		gem_execbuf(fd, &execbuf);
+	}
+
+	return handle;
+}
+
+static void sigiter(int sig, siginfo_t *info, void *arg)
+{
+	*batch = MI_BATCH_BUFFER_END;
+	__sync_synchronize();
+}
+
+static timer_t setup_batch_exit_timer(int64_t ns)
+{
+	timer_t timer;
+	struct sigevent sev;
+	struct sigaction act;
+	struct itimerspec its;
+
+	memset(&sev, 0, sizeof(sev));
+	sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
+	sev.sigev_notify_thread_id = gettid();
+	sev.sigev_signo = SIGRTMIN + 1;
+	igt_assert(timer_create(CLOCK_MONOTONIC, &sev, &timer) == 0);
+	igt_assert(timer > 0);
+
+	memset(&act, 0, sizeof(act));
+	act.sa_sigaction = sigiter;
+	act.sa_flags = SA_SIGINFO;
+	igt_assert(sigaction(SIGRTMIN + 1, &act, NULL) == 0);
+
+	memset(&its, 0, sizeof(its));
+	its.it_value.tv_sec = ns / NSEC_PER_SEC;
+	its.it_value.tv_nsec = ns % NSEC_PER_SEC;
+	igt_assert(timer_settime(timer, 0, &its, NULL) == 0);
+
+	return timer;
+}
+
+/**
+ * igt_spin_batch:
+ * @fd: open i915 drm file descriptor
+ * @ns: amount of time in nanoseconds the batch executes after terminating.
+ *      If value is less than 0, execute batch forever.
+ * @engine: Ring to execute batch OR'd with execbuf flags. If value is less
+ *          than 0, execute on all available rings.
+ * @dep_handle: handle to a buffer object dependency. If greater than 0, add a
+ *              relocation entry to this buffer within the batch.
+ *
+ * Start a recursive batch on a ring that terminates after an exact amount
+ * of time has elapsed. Immediately returns a #igt_spin_t that contains the
+ * batch's handle that can be waited upon. The returned structure must be passed to
+ * igt_post_spin_batch() for post-processing.
+ *
+ * Returns:
+ * Structure with helper internal state for igt_post_spin_batch().
+ */
+igt_spin_t igt_spin_batch(int fd, int64_t ns, int engine, unsigned dep_handle)
+{
+	timer_t timer;
+	uint32_t handle = emit_recursive_batch(fd, engine, dep_handle);
+	int64_t wait_timeout = 0;
+	igt_assert_eq(gem_wait(fd, handle, &wait_timeout), -ETIME);
+
+	if (ns < 1) {
+		if (ns == 0) {
+			*batch = MI_BATCH_BUFFER_END;
+			__sync_synchronize();
+			return (igt_spin_t){ handle, batch, 0};
+		}
+		return (igt_spin_t){ handle, batch, 0 };
+	}
+	timer = setup_batch_exit_timer(ns);
+
+	return (igt_spin_t){ handle, batch, timer };
+}
+
+/**
+ * igt_post_spin_batch:
+ * @fd: open i915 drm file descriptor
+ * @arg: spin batch state from igt_spin_batch()
+ *
+ * This function does the necessary post-processing after starting a recursive
+ * batch with igt_spin_batch().
+ */
+void igt_post_spin_batch(int fd, igt_spin_t arg)
+{
+	if (arg.handle == 0)
+		return;
+
+	if (arg.timer > 0)
+		timer_delete(arg.timer);
+
+	gem_close(fd, arg.handle);
+	munmap(arg.batch, 4096);
+}
+
+
+/**
+ * igt_spin_batch_wait:
+ * @fd: open i915 drm file descriptor
+ * @ns: amount of time in nanoseconds the batch executes after terminating.
+ *      If value is less than 0, execute batch forever.
+ * @engine: ring to execute batch OR'd with execbuf flags. If value is less
+ *          than 0, execute on all available rings.
+ * @dep_handle: handle to a buffer object dependency. If greater than 0, include
+ *              this buffer on the wait dependency
+ *
+ * This is similar to igt_spin_batch(), but waits on the recursive batch to finish
+ * instead of returning right away. The function also does the necessary
+ * post-processing automatically if set to timeout.
+ */
+void igt_spin_batch_wait(int fd, int64_t ns, int engine, unsigned dep_handle)
+{
+	igt_spin_t spin = igt_spin_batch(fd, ns, engine, dep_handle);
+	int64_t wait_timeout = ns + (0.5 * NSEC_PER_SEC);
+	igt_assert_eq(gem_wait(fd, spin.handle, &wait_timeout), 0);
+
+	igt_post_spin_batch(fd, spin);
+}
diff --git a/lib/igt_dummyload.h b/lib/igt_dummyload.h
new file mode 100644
index 0000000..79ead2c
--- /dev/null
+++ b/lib/igt_dummyload.h
@@ -0,0 +1,42 @@ 
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __IGT_DUMMYLOAD_H__
+#define __IGT_DUMMYLOAD_H__
+
+typedef struct igt_spin {
+	unsigned handle;
+	uint32_t *batch;
+	timer_t timer;
+} igt_spin_t;
+
+
+igt_spin_t igt_spin_batch(int fd, int64_t ns, int engine, unsigned dep_handle);
+
+void igt_post_spin_batch(int fd, igt_spin_t arg);
+
+void igt_spin_batch_wait(int fd, int64_t ns, int engine, unsigned dep_handle);
+
+
+#endif /* __IGT_DUMMYLOAD_H__ */