From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
In order to use userptr, the kernel tracks the owner's mm with a
mmu_notifier. Setting that is very expensive - it involves taking all
mm_locks and a stop_machine(). This tracking lives only for as long as
the client is using userptr objects - so if the client allocates then
frees a userptr in a loop, we will be executing that heavyweight setup
everytime. To ammoritize this cost, just leak the test bo and the single
backing page we use for detecting userptr.
v2: Free the object and memory when bufmgr is destroyed.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
intel/intel_bufmgr_gem.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index f5d6130..969ade5 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -132,6 +132,11 @@ typedef struct _drm_intel_bufmgr_gem {
unsigned int has_vebox : 1;
bool fenced_relocs;
+ struct {
+ void *ptr;
+ uint32_t handle;
+ } userptr_active;
+
char *aub_filename;
FILE *aub_file;
uint32_t aub_offset;
@@ -943,7 +948,6 @@ has_userptr(drm_intel_bufmgr_gem *bufmgr_gem)
void *ptr;
long pgsz;
struct drm_i915_gem_userptr userptr;
- struct drm_gem_close close_bo;
pgsz = sysconf(_SC_PAGESIZE);
assert(pgsz > 0);
@@ -970,15 +974,15 @@ retry:
return false;
}
- memclear(close_bo);
- close_bo.handle = userptr.handle;
- ret = drmIoctl(bufmgr_gem->fd, DRM_IOCTL_GEM_CLOSE, &close_bo);
- free(ptr);
- if (ret) {
- fprintf(stderr, "Failed to release test userptr object! (%d) "
- "i915 kernel driver may not be sane!\n", errno);
- return false;
- }
+ /* We don't release the userptr bo here as we want to keep the
+ * kernel mm tracking alive for our lifetime. The first time we
+ * create a userptr object the kernel has to install a mmu_notifer
+ * which is a heavyweight operation (e.g. it requires taking all
+ * mm_locks and stop_machine()).
+ */
+
+ bufmgr_gem->userptr_active.ptr = ptr;
+ bufmgr_gem->userptr_active.handle = userptr.handle;
return true;
}
@@ -1805,7 +1809,8 @@ static void
drm_intel_bufmgr_gem_destroy(drm_intel_bufmgr *bufmgr)
{
drm_intel_bufmgr_gem *bufmgr_gem = (drm_intel_bufmgr_gem *) bufmgr;
- int i;
+ struct drm_gem_close close_bo;
+ int i, ret;
free(bufmgr_gem->exec2_objects);
free(bufmgr_gem->exec_objects);
@@ -1829,6 +1834,18 @@ drm_intel_bufmgr_gem_destroy(drm_intel_bufmgr *bufmgr)
}
}
+ /* Release userptr bo kept hanging around for optimisation. */
+ if (bufmgr_gem->userptr_active.ptr) {
+ memclear(close_bo);
+ close_bo.handle = bufmgr_gem->userptr_active.handle;
+ ret = drmIoctl(bufmgr_gem->fd, DRM_IOCTL_GEM_CLOSE, &close_bo);
+ free(bufmgr_gem->userptr_active.ptr);
+ if (ret)
+ fprintf(stderr,
+ "Failed to release test userptr object! (%d) "
+ "i915 kernel driver may not be sane!\n", errno);
+ }
+
free(bufmgr);
}
--
2.3.5
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