[PATCH 11/16] drm/amdkfd: Simplify event ID and signal slot management
Felix Kuehling
Felix.Kuehling at amd.com
Sat Oct 21 00:23:15 UTC 2017
Signal slots are identical to event IDs.
Replace the used_slot_bitmap and events hash table with an IDR to
allocate and lookup event IDs and signal slots more efficiently.
Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
---
drivers/gpu/drm/amd/amdkfd/kfd_events.c | 230 ++++++++++----------------------
drivers/gpu/drm/amd/amdkfd/kfd_events.h | 14 +-
drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 6 +-
3 files changed, 80 insertions(+), 170 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
index f800e48..cddd4b9 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
@@ -41,24 +41,16 @@ struct kfd_event_waiter {
bool activated; /* Becomes true when event is signaled */
};
-#define SLOTS_PER_PAGE KFD_SIGNAL_EVENT_LIMIT
-#define SLOT_BITMAP_LONGS BITS_TO_LONGS(SLOTS_PER_PAGE)
-
/*
- * Over-complicated pooled allocator for event notification slots.
- *
* Each signal event needs a 64-bit signal slot where the signaler will write
- * a 1 before sending an interrupt.l (This is needed because some interrupts
+ * a 1 before sending an interrupt. (This is needed because some interrupts
* do not contain enough spare data bits to identify an event.)
- * We get whole pages from vmalloc and map them to the process VA.
- * Individual signal events are then allocated a slot in a page.
+ * We get whole pages and map them to the process VA.
+ * Individual signal events use their event_id as slot index.
*/
-
struct kfd_signal_page {
uint64_t *kernel_address;
uint64_t __user *user_address;
- unsigned int free_slots;
- unsigned long used_slot_bitmap[SLOT_BITMAP_LONGS];
};
/*
@@ -73,34 +65,6 @@ static uint64_t *page_slots(struct kfd_signal_page *page)
return page->kernel_address;
}
-static bool allocate_free_slot(struct kfd_process *process,
- unsigned int *out_slot_index)
-{
- struct kfd_signal_page *page = process->signal_page;
- unsigned int slot;
-
- if (!page || page->free_slots == 0) {
- pr_debug("No free event signal slots were found for process %p\n",
- process);
-
- return false;
- }
-
- slot = find_first_zero_bit(page->used_slot_bitmap, SLOTS_PER_PAGE);
-
- __set_bit(slot, page->used_slot_bitmap);
- page->free_slots--;
-
- page_slots(page)[slot] = UNSIGNALED_EVENT_SLOT;
-
- *out_slot_index = slot;
-
- pr_debug("Allocated event signal slot in page %p, slot %d\n",
- page, slot);
-
- return true;
-}
-
static struct kfd_signal_page *allocate_signal_page(struct kfd_process *p)
{
void *backing_store;
@@ -110,8 +74,6 @@ static struct kfd_signal_page *allocate_signal_page(struct kfd_process *p)
if (!page)
return NULL;
- page->free_slots = SLOTS_PER_PAGE;
-
backing_store = (void *) __get_free_pages(GFP_KERNEL,
get_order(KFD_SIGNAL_EVENT_LIMIT * 8));
if (!backing_store)
@@ -132,28 +94,26 @@ static struct kfd_signal_page *allocate_signal_page(struct kfd_process *p)
return NULL;
}
-static bool allocate_event_notification_slot(struct kfd_process *p,
- unsigned int *signal_slot_index)
+static int allocate_event_notification_slot(struct kfd_process *p,
+ struct kfd_event *ev)
{
+ int id;
+
if (!p->signal_page) {
p->signal_page = allocate_signal_page(p);
if (!p->signal_page)
- return false;
+ return -ENOMEM;
}
- return allocate_free_slot(p, signal_slot_index);
-}
+ id = idr_alloc(&p->event_idr, ev, 0, KFD_SIGNAL_EVENT_LIMIT,
+ GFP_KERNEL);
+ if (id < 0)
+ return id;
-/* Assumes that the process's event_mutex is locked. */
-static void release_event_notification_slot(struct kfd_signal_page *page,
- size_t slot_index)
-{
- __clear_bit(slot_index, page->used_slot_bitmap);
- page->free_slots++;
+ ev->event_id = id;
+ page_slots(p->signal_page)[id] = UNSIGNALED_EVENT_SLOT;
- /* We don't free signal pages, they are retained by the process
- * and reused until it exits.
- */
+ return 0;
}
/*
@@ -162,89 +122,32 @@ static void release_event_notification_slot(struct kfd_signal_page *page,
*/
static struct kfd_event *lookup_event_by_id(struct kfd_process *p, uint32_t id)
{
- struct kfd_event *ev;
-
- hash_for_each_possible(p->events, ev, events, id)
- if (ev->event_id == id)
- return ev;
-
- return NULL;
-}
-
-/*
- * Produce a kfd event id for a nonsignal event.
- * These are arbitrary numbers, so we do a sequential search through
- * the hash table for an unused number.
- */
-static u32 make_nonsignal_event_id(struct kfd_process *p)
-{
- u32 id;
-
- for (id = p->next_nonsignal_event_id;
- id < KFD_LAST_NONSIGNAL_EVENT_ID &&
- lookup_event_by_id(p, id);
- id++)
- ;
-
- if (id < KFD_LAST_NONSIGNAL_EVENT_ID) {
-
- /*
- * What if id == LAST_NONSIGNAL_EVENT_ID - 1?
- * Then next_nonsignal_event_id = LAST_NONSIGNAL_EVENT_ID so
- * the first loop fails immediately and we proceed with the
- * wraparound loop below.
- */
- p->next_nonsignal_event_id = id + 1;
-
- return id;
- }
-
- for (id = KFD_FIRST_NONSIGNAL_EVENT_ID;
- id < KFD_LAST_NONSIGNAL_EVENT_ID &&
- lookup_event_by_id(p, id);
- id++)
- ;
-
-
- if (id < KFD_LAST_NONSIGNAL_EVENT_ID) {
- p->next_nonsignal_event_id = id + 1;
- return id;
- }
-
- p->next_nonsignal_event_id = KFD_FIRST_NONSIGNAL_EVENT_ID;
- return 0;
-}
-
-static struct kfd_event *lookup_event_by_page_slot(struct kfd_process *p,
- unsigned int signal_slot)
-{
- return lookup_event_by_id(p, signal_slot);
+ return idr_find(&p->event_idr, id);
}
static int create_signal_event(struct file *devkfd,
struct kfd_process *p,
struct kfd_event *ev)
{
+ int ret;
+
if (p->signal_event_count == KFD_SIGNAL_EVENT_LIMIT) {
if (!p->signal_event_limit_reached) {
pr_warn("Signal event wasn't created because limit was reached\n");
p->signal_event_limit_reached = true;
}
- return -ENOMEM;
+ return -ENOSPC;
}
- if (!allocate_event_notification_slot(p, &ev->signal_slot_index)) {
+ ret = allocate_event_notification_slot(p, ev);
+ if (ret) {
pr_warn("Signal event wasn't created because out of kernel memory\n");
- return -ENOMEM;
+ return ret;
}
p->signal_event_count++;
- ev->user_signal_address =
- &p->signal_page->user_address[ev->signal_slot_index];
-
- ev->event_id = ev->signal_slot_index;
-
+ ev->user_signal_address = &p->signal_page->user_address[ev->event_id];
pr_debug("Signal event number %zu created with id %d, address %p\n",
p->signal_event_count, ev->event_id,
ev->user_signal_address);
@@ -252,16 +155,20 @@ static int create_signal_event(struct file *devkfd,
return 0;
}
-/*
- * No non-signal events are supported yet.
- * We create them as events that never signal.
- * Set event calls from user-mode are failed.
- */
static int create_other_event(struct kfd_process *p, struct kfd_event *ev)
{
- ev->event_id = make_nonsignal_event_id(p);
- if (ev->event_id == 0)
- return -ENOMEM;
+ /* Cast KFD_LAST_NONSIGNAL_EVENT to uint32_t. This allows an
+ * intentional integer overflow to -1 without a compiler
+ * warning. idr_alloc treats a negative value as "maximum
+ * signed integer".
+ */
+ int id = idr_alloc(&p->event_idr, ev, KFD_FIRST_NONSIGNAL_EVENT_ID,
+ (uint32_t)KFD_LAST_NONSIGNAL_EVENT_ID + 1,
+ GFP_KERNEL);
+
+ if (id < 0)
+ return id;
+ ev->event_id = id;
return 0;
}
@@ -269,9 +176,8 @@ static int create_other_event(struct kfd_process *p, struct kfd_event *ev)
void kfd_event_init_process(struct kfd_process *p)
{
mutex_init(&p->event_mutex);
- hash_init(p->events);
+ idr_init(&p->event_idr);
p->signal_page = NULL;
- p->next_nonsignal_event_id = KFD_FIRST_NONSIGNAL_EVENT_ID;
p->signal_event_count = 0;
}
@@ -284,25 +190,22 @@ static void destroy_event(struct kfd_process *p, struct kfd_event *ev)
waiter->event = NULL;
wake_up_all(&ev->wq);
- if ((ev->type == KFD_EVENT_TYPE_SIGNAL ||
- ev->type == KFD_EVENT_TYPE_DEBUG) && p->signal_page) {
- release_event_notification_slot(p->signal_page,
- ev->signal_slot_index);
+ if (ev->type == KFD_EVENT_TYPE_SIGNAL ||
+ ev->type == KFD_EVENT_TYPE_DEBUG)
p->signal_event_count--;
- }
- hash_del(&ev->events);
+ idr_remove(&p->event_idr, ev->event_id);
kfree(ev);
}
static void destroy_events(struct kfd_process *p)
{
struct kfd_event *ev;
- struct hlist_node *tmp;
- unsigned int hash_bkt;
+ uint32_t id;
- hash_for_each_safe(p->events, hash_bkt, tmp, ev, events)
+ idr_for_each_entry(&p->event_idr, ev, id)
destroy_event(p, ev);
+ idr_destroy(&p->event_idr);
}
/*
@@ -365,7 +268,7 @@ int kfd_event_create(struct file *devkfd, struct kfd_process *p,
if (!ret) {
*event_page_offset = KFD_MMAP_EVENTS_MASK;
*event_page_offset <<= PAGE_SHIFT;
- *event_slot_index = ev->signal_slot_index;
+ *event_slot_index = ev->event_id;
}
break;
default:
@@ -374,8 +277,6 @@ int kfd_event_create(struct file *devkfd, struct kfd_process *p,
}
if (!ret) {
- hash_add(p->events, &ev->events, ev->event_id);
-
*event_id = ev->event_id;
*event_trigger_data = ev->event_id;
} else {
@@ -465,17 +366,7 @@ int kfd_reset_event(struct kfd_process *p, uint32_t event_id)
static void acknowledge_signal(struct kfd_process *p, struct kfd_event *ev)
{
- page_slots(p->signal_page)[ev->signal_slot_index] =
- UNSIGNALED_EVENT_SLOT;
-}
-
-static bool is_slot_signaled(struct kfd_process *p, unsigned int index)
-{
- if (!p->signal_page)
- return false;
- else
- return page_slots(p->signal_page)[index] !=
- UNSIGNALED_EVENT_SLOT;
+ page_slots(p->signal_page)[ev->event_id] = UNSIGNALED_EVENT_SLOT;
}
static void set_event_from_interrupt(struct kfd_process *p,
@@ -514,13 +405,31 @@ void kfd_signal_event_interrupt(unsigned int pasid, uint32_t partial_id,
* ignore it, but we could use any bits we did receive to
* search faster.
*/
- unsigned int i;
+ uint64_t *slots = page_slots(p->signal_page);
+ uint32_t id;
+
+ if (p->signal_event_count < KFD_SIGNAL_EVENT_LIMIT/2) {
+ /* With relatively few events, it's faster to
+ * iterate over the event IDR
+ */
+ idr_for_each_entry(&p->event_idr, ev, id) {
+ if (id >= KFD_SIGNAL_EVENT_LIMIT)
+ break;
- for (i = 0; i < SLOTS_PER_PAGE; i++)
- if (is_slot_signaled(p, i)) {
- ev = lookup_event_by_page_slot(p, i);
- set_event_from_interrupt(p, ev);
+ if (slots[id] != UNSIGNALED_EVENT_SLOT)
+ set_event_from_interrupt(p, ev);
}
+ } else {
+ /* With relatively many events, it's faster to
+ * iterate over the signal slots and lookup
+ * only signaled events from the IDR.
+ */
+ for (id = 0; id < KFD_SIGNAL_EVENT_LIMIT; id++)
+ if (slots[id] != UNSIGNALED_EVENT_SLOT) {
+ ev = lookup_event_by_id(p, id);
+ set_event_from_interrupt(p, ev);
+ }
+ }
}
mutex_unlock(&p->event_mutex);
@@ -832,12 +741,13 @@ static void lookup_events_by_type_and_signal(struct kfd_process *p,
{
struct kfd_hsa_memory_exception_data *ev_data;
struct kfd_event *ev;
- int bkt;
+ uint32_t id;
bool send_signal = true;
ev_data = (struct kfd_hsa_memory_exception_data *) event_data;
- hash_for_each(p->events, bkt, ev, events)
+ id = KFD_FIRST_NONSIGNAL_EVENT_ID;
+ idr_for_each_entry_continue(&p->event_idr, ev, id)
if (ev->type == type) {
send_signal = false;
dev_dbg(kfd_device,
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.h b/drivers/gpu/drm/amd/amdkfd/kfd_events.h
index f85fcee..abca5bf 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.h
@@ -31,9 +31,13 @@
#include "kfd_priv.h"
#include <uapi/linux/kfd_ioctl.h>
-#define KFD_EVENT_ID_NONSIGNAL_MASK 0x80000000U
-#define KFD_FIRST_NONSIGNAL_EVENT_ID KFD_EVENT_ID_NONSIGNAL_MASK
-#define KFD_LAST_NONSIGNAL_EVENT_ID UINT_MAX
+/*
+ * IDR supports non-negative integer IDs. Small IDs are used for
+ * signal events to match their signal slot. Use the upper half of the
+ * ID space for non-signal events.
+ */
+#define KFD_FIRST_NONSIGNAL_EVENT_ID ((INT_MAX >> 1) + 1)
+#define KFD_LAST_NONSIGNAL_EVENT_ID INT_MAX
/*
* Written into kfd_signal_slot_t to indicate that the event is not signaled.
@@ -47,9 +51,6 @@ struct kfd_event_waiter;
struct signal_page;
struct kfd_event {
- /* All events in process, rooted at kfd_process.events. */
- struct hlist_node events;
-
u32 event_id;
bool signaled;
@@ -60,7 +61,6 @@ struct kfd_event {
wait_queue_head_t wq; /* List of event waiters. */
/* Only for signal events. */
- unsigned int signal_slot_index;
uint64_t __user *user_signal_address;
/* type specific data */
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index c1b3ee2..ebae8e1 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -31,6 +31,7 @@
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/kfd_ioctl.h>
+#include <linux/idr.h>
#include <kgd_kfd_interface.h>
#include "amd_shared.h"
@@ -538,11 +539,10 @@ struct kfd_process {
/* Event-related data */
struct mutex event_mutex;
- /* All events in process hashed by ID, linked on kfd_event.events. */
- DECLARE_HASHTABLE(events, 4);
+ /* Event ID allocator and lookup */
+ struct idr event_idr;
/* Event page */
struct kfd_signal_page *signal_page;
- u32 next_nonsignal_event_id;
size_t signal_event_count;
bool signal_event_limit_reached;
};
--
2.7.4
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