Re: [Intel-gfx] [PATCH] intel: Leak the userptr test bo
On 04/14/2015 05:31 PM, Chris Wilson wrote: 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 Spellcheck on this line. Also, if drm_intel_bufmgr_destroy is what I think it is, I think for correctness we would need to release that stuff there. What do you think? I could respin it with that if you are too busy? Regards, Tvrtko ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Re: [Intel-gfx] [PATCH] intel: Leak the userptr test bo
On Wed, Apr 15, 2015 at 03:08:56PM +0100, Tvrtko Ursulin wrote: On 04/14/2015 05:31 PM, Chris Wilson wrote: 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 Spellcheck on this line. Also, if drm_intel_bufmgr_destroy is what I think it is, I think for correctness we would need to release that stuff there. What do you think? I could respin it with that if you are too busy? I contemplated it, then decided I was too lazy to store a couple of pointers. If you want to respin with that and push, please do. -Chris -- Chris Wilson, Intel Open Source Technology Centre ___ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
[Intel-gfx] [PATCH] intel: Leak the userptr test bo
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.
Signed-off-by: Chris Wilson ch...@chris-wilson.co.uk
Cc: Tvrtko Ursulin tvrtko.ursu...@intel.com
---
intel/intel_bufmgr_gem.c | 15 ++-
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index a938441..51f8afe 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -976,15 +976,12 @@ 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()).
+*/
return true;
}
--
2.1.4
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