[PATCH 11/16] drm/amdkfd: Simplify event ID and signal slot management
Oded Gabbay
oded.gabbay at gmail.com
Wed Oct 25 10:42:32 UTC 2017
On Sat, Oct 21, 2017 at 3:23 AM, Felix Kuehling <Felix.Kuehling at amd.com> wrote:
> 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
>
This patch is:
Acked-by: Oded Gabbay <oded.gabbay at gmail.com>
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