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drm/amdkfd: simplify drain retry fault 

unmap range always increase atomic svms->drain_pagefaults to simplify
both parent range and child range unmap, page fault handle ignores the
retry fault if svms->drain_pagefaults is set to speed up interrupt
handling. svm_range_drain_retry_fault restart draining if another
range unmap from cpu.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Philip Yang 2021-11-19 17:02:50 -05:00 committed by Alex Deucher
parent 7ad153db58
commit 2e4477282c
2 changed files with 23 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/gpu/drm/amd/amdkfd/kfd_priv.h
View File

@ -767,7 +767,7 @@ struct svm_range_list {
struct list_head deferred_range_list;
spinlock_t deferred_list_lock;
atomic_t evicted_ranges;
bool drain_pagefaults;
atomic_t drain_pagefaults;
struct delayed_work restore_work;
DECLARE_BITMAP(bitmap_supported, MAX_GPU_INSTANCE);
struct task_struct *faulting_task;

30
drivers/gpu/drm/amd/amdkfd/kfd_svm.c
View File

@ -1957,10 +1957,16 @@ static void svm_range_drain_retry_fault(struct svm_range_list *svms)
{
struct kfd_process_device *pdd;
struct kfd_process *p;
int drain;
uint32_t i;
p = container_of(svms, struct kfd_process, svms);
restart:
drain = atomic_read(&svms->drain_pagefaults);
if (!drain)
return;
for_each_set_bit(i, svms->bitmap_supported, p->n_pdds) {
pdd = p->pdds[i];
if (!pdd)
@ -1972,6 +1978,8 @@ static void svm_range_drain_retry_fault(struct svm_range_list *svms)
&pdd->dev->adev->irq.ih1);
pr_debug("drain retry fault gpu %d svms 0x%p done\n", i, svms);
}
if (atomic_cmpxchg(&svms->drain_pagefaults, drain, 0) != drain)
goto restart;
}
static void svm_range_deferred_list_work(struct work_struct *work)
@ -1997,8 +2005,7 @@ retry:
/* Checking for the need to drain retry faults must be inside
* mmap write lock to serialize with munmap notifiers.
*/
if (unlikely(READ_ONCE(svms->drain_pagefaults))) {
WRITE_ONCE(svms->drain_pagefaults, false);
if (unlikely(atomic_read(&svms->drain_pagefaults))) {
mmap_write_unlock(mm);
svm_range_drain_retry_fault(svms);
goto retry;
@ -2045,12 +2052,6 @@ svm_range_add_list_work(struct svm_range_list *svms, struct svm_range *prange,
struct mm_struct *mm, enum svm_work_list_ops op)
{
spin_lock(&svms->deferred_list_lock);
/* Make sure pending page faults are drained in the deferred worker
* before the range is freed to avoid straggler interrupts on
* unmapped memory causing "phantom faults".
*/
if (op == SVM_OP_UNMAP_RANGE)
svms->drain_pagefaults = true;
/* if prange is on the deferred list */
if (!list_empty(&prange->deferred_list)) {
pr_debug("update exist prange 0x%p work op %d\n", prange, op);
@ -2129,6 +2130,12 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange,
pr_debug("svms 0x%p prange 0x%p [0x%lx 0x%lx] [0x%lx 0x%lx]\n", svms,
prange, prange->start, prange->last, start, last);
/* Make sure pending page faults are drained in the deferred worker
* before the range is freed to avoid straggler interrupts on
* unmapped memory causing "phantom faults".
*/
atomic_inc(&svms->drain_pagefaults);
unmap_parent = start <= prange->start && last >= prange->last;
list_for_each_entry(pchild, &prange->child_list, child_list) {
@ -2594,6 +2601,11 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
pr_debug("restoring svms 0x%p fault address 0x%llx\n", svms, addr);
if (atomic_read(&svms->drain_pagefaults)) {
pr_debug("draining retry fault, drop fault 0x%llx\n", addr);
goto out;
}
/* p->lead_thread is available as kfd_process_wq_release flush the work
* before releasing task ref.
*/
@ -2740,6 +2752,7 @@ void svm_range_list_fini(struct kfd_process *p)
* Ensure no retry fault comes in afterwards, as page fault handler will
* not find kfd process and take mm lock to recover fault.
*/
atomic_inc(&p->svms.drain_pagefaults);
svm_range_drain_retry_fault(&p->svms);
@ -2763,6 +2776,7 @@ int svm_range_list_init(struct kfd_process *p)
mutex_init(&svms->lock);
INIT_LIST_HEAD(&svms->list);
atomic_set(&svms->evicted_ranges, 0);
atomic_set(&svms->drain_pagefaults, 0);
INIT_DELAYED_WORK(&svms->restore_work, svm_range_restore_work);
INIT_WORK(&svms->deferred_list_work, svm_range_deferred_list_work);
INIT_LIST_HEAD(&svms->deferred_range_list);