Re: [RFC][PATCH v6 4/7] drm: ttm_pool: Rework ttm_pool to use drm_page_pool
From: Christian König
Date: Fri Feb 05 2021 - 03:52:22 EST
Am 05.02.21 um 09:06 schrieb John Stultz:
This patch reworks the ttm_pool logic to utilize the recently
added drm_page_pool code.
Basically all the ttm_pool_type structures are replaced with
drm_page_pool pointers, and since the drm_page_pool logic has
its own shrinker, we can remove all of the ttm_pool shrinker
logic.
NOTE: There is one mismatch in the interfaces I'm not totally
happy with. The ttm_pool tracks all of its pooled pages across
a number of different pools, and tries to keep this size under
the specified page_pool_size value. With the drm_page_pool,
there may other users, however there is still one global
shrinker list of pools. So we can't easily reduce the ttm
pool under the ttm specified size without potentially doing
a lot of shrinking to other non-ttm pools. So either we can:
1) Try to split it so each user of drm_page_pools manages its
own pool shrinking.
2) Push the max value into the drm_page_pool, and have it
manage shrinking to fit under that global max. Then share
those size/max values out so the ttm_pool debug output
can have more context.
I've taken the second path in this patch set, but wanted to call
it out so folks could look closely.
Option 3: Move the debugging code into the drm_page_pool as well.
I strong think that will be a hard requirement from Daniel for
upstreaming this.
Christian.
Thoughts would be greatly appreciated here!
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Liam Mark <lmark@xxxxxxxxxxxxxx>
Cc: Chris Goldsworthy <cgoldswo@xxxxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Brian Starkey <Brian.Starkey@xxxxxxx>
Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Sandeep Patil <sspatil@xxxxxxxxxx>
Cc: Daniel Mentz <danielmentz@xxxxxxxxxx>
Cc: Ørjan Eide <orjan.eide@xxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
Cc: Simon Ser <contact@xxxxxxxxxxx>
Cc: James Jones <jajones@xxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 1 +
drivers/gpu/drm/ttm/ttm_pool.c | 199 +++++++--------------------------
include/drm/ttm/ttm_pool.h | 23 +---
3 files changed, 41 insertions(+), 182 deletions(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index d16bf340ed2e..d427abefabfb 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -181,6 +181,7 @@ config DRM_PAGE_POOL
config DRM_TTM
tristate
depends on DRM && MMU
+ select DRM_PAGE_POOL
help
GPU memory management subsystem for devices with multiple
GPU memory types. Will be enabled automatically if a device driver
diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
index eca36678f967..dbbaf55ca5df 100644
--- a/drivers/gpu/drm/ttm/ttm_pool.c
+++ b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -37,6 +37,7 @@
#ifdef CONFIG_X86
#include <asm/set_memory.h>
#endif
+#include <drm/page_pool.h>
#include <drm/ttm/ttm_pool.h>
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_tt.h>
@@ -63,15 +64,13 @@ module_param(page_pool_size, ulong, 0644);
static atomic_long_t allocated_pages;
-static struct ttm_pool_type global_write_combined[MAX_ORDER];
-static struct ttm_pool_type global_uncached[MAX_ORDER];
+static struct drm_page_pool *global_write_combined[MAX_ORDER];
+static struct drm_page_pool *global_uncached[MAX_ORDER];
-static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];
-static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];
+static struct drm_page_pool *global_dma32_write_combined[MAX_ORDER];
+static struct drm_page_pool *global_dma32_uncached[MAX_ORDER];
static struct mutex shrinker_lock;
-static struct list_head shrinker_list;
-static struct shrinker mm_shrinker;
/* Allocate pages of size 1 << order with the given gfp_flags */
static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
@@ -223,79 +222,26 @@ static void ttm_pool_unmap(struct ttm_pool *pool, dma_addr_t dma_addr,
DMA_BIDIRECTIONAL);
}
-/* Give pages into a specific pool_type */
-static void ttm_pool_type_give(struct ttm_pool_type *pt, struct page *p)
-{
- spin_lock(&pt->lock);
- list_add(&p->lru, &pt->pages);
- spin_unlock(&pt->lock);
- atomic_long_add(1 << pt->order, &allocated_pages);
-}
-
-/* Take pages from a specific pool_type, return NULL when nothing available */
-static struct page *ttm_pool_type_take(struct ttm_pool_type *pt)
-{
- struct page *p;
-
- spin_lock(&pt->lock);
- p = list_first_entry_or_null(&pt->pages, typeof(*p), lru);
- if (p) {
- atomic_long_sub(1 << pt->order, &allocated_pages);
- list_del(&p->lru);
- }
- spin_unlock(&pt->lock);
-
- return p;
-}
-
-/* Initialize and add a pool type to the global shrinker list */
-static void ttm_pool_type_init(struct ttm_pool_type *pt, struct ttm_pool *pool,
- enum ttm_caching caching, unsigned int order)
-{
- pt->pool = pool;
- pt->caching = caching;
- pt->order = order;
- spin_lock_init(&pt->lock);
- INIT_LIST_HEAD(&pt->pages);
-
- mutex_lock(&shrinker_lock);
- list_add_tail(&pt->shrinker_list, &shrinker_list);
- mutex_unlock(&shrinker_lock);
-}
-
-/* Remove a pool_type from the global shrinker list and free all pages */
-static void ttm_pool_type_fini(struct ttm_pool_type *pt)
-{
- struct page *p, *tmp;
-
- mutex_lock(&shrinker_lock);
- list_del(&pt->shrinker_list);
- mutex_unlock(&shrinker_lock);
-
- list_for_each_entry_safe(p, tmp, &pt->pages, lru)
- ttm_pool_free_page(p, pt->order);
-}
-
/* Return the pool_type to use for the given caching and order */
-static struct ttm_pool_type *ttm_pool_select_type(struct ttm_pool *pool,
+static struct drm_page_pool *ttm_pool_select_type(struct ttm_pool *pool,
enum ttm_caching caching,
unsigned int order)
{
if (pool->use_dma_alloc)
- return &pool->caching[caching].orders[order];
+ return pool->caching[caching].orders[order];
#ifdef CONFIG_X86
switch (caching) {
case ttm_write_combined:
if (pool->use_dma32)
- return &global_dma32_write_combined[order];
+ return global_dma32_write_combined[order];
- return &global_write_combined[order];
+ return global_write_combined[order];
case ttm_uncached:
if (pool->use_dma32)
- return &global_dma32_uncached[order];
+ return global_dma32_uncached[order];
- return &global_uncached[order];
+ return global_uncached[order];
default:
break;
}
@@ -304,30 +250,6 @@ static struct ttm_pool_type *ttm_pool_select_type(struct ttm_pool *pool,
return NULL;
}
-/* Free pages using the global shrinker list */
-static unsigned int ttm_pool_shrink(void)
-{
- struct ttm_pool_type *pt;
- unsigned int num_freed;
- struct page *p;
-
- mutex_lock(&shrinker_lock);
- pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);
-
- p = ttm_pool_type_take(pt);
- if (p) {
- ttm_pool_free_page(p, pt->order);
- num_freed = 1 << pt->order;
- } else {
- num_freed = 0;
- }
-
- list_move_tail(&pt->shrinker_list, &shrinker_list);
- mutex_unlock(&shrinker_lock);
-
- return num_freed;
-}
-
/* Return the allocation order based for a page */
static unsigned int ttm_pool_page_order(struct ttm_pool *pool, struct page *p)
{
@@ -377,10 +299,10 @@ int ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
for (order = min(MAX_ORDER - 1UL, __fls(num_pages)); num_pages;
order = min_t(unsigned int, order, __fls(num_pages))) {
bool apply_caching = false;
- struct ttm_pool_type *pt;
+ struct drm_page_pool *pt;
pt = ttm_pool_select_type(pool, tt->caching, order);
- p = pt ? ttm_pool_type_take(pt) : NULL;
+ p = pt ? drm_page_pool_fetch(pt) : NULL;
if (p) {
apply_caching = true;
} else {
@@ -462,7 +384,7 @@ void ttm_pool_free(struct ttm_pool *pool, struct ttm_tt *tt)
for (i = 0; i < tt->num_pages; ) {
struct page *p = tt->pages[i];
unsigned int order, num_pages;
- struct ttm_pool_type *pt;
+ struct drm_page_pool *pt;
order = ttm_pool_page_order(pool, p);
num_pages = 1ULL << order;
@@ -473,15 +395,12 @@ void ttm_pool_free(struct ttm_pool *pool, struct ttm_tt *tt)
pt = ttm_pool_select_type(pool, tt->caching, order);
if (pt)
- ttm_pool_type_give(pt, tt->pages[i]);
+ drm_page_pool_add(pt, tt->pages[i]);
else
ttm_pool_free_page(tt->pages[i], order);
i += num_pages;
}
-
- while (atomic_long_read(&allocated_pages) > page_pool_size)
- ttm_pool_shrink();
}
EXPORT_SYMBOL(ttm_pool_free);
@@ -508,8 +427,8 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i)
for (j = 0; j < MAX_ORDER; ++j)
- ttm_pool_type_init(&pool->caching[i].orders[j],
- pool, i, j);
+ pool->caching[i].orders[j] = drm_page_pool_create(j,
+ ttm_pool_free_page);
}
/**
@@ -526,33 +445,18 @@ void ttm_pool_fini(struct ttm_pool *pool)
for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i)
for (j = 0; j < MAX_ORDER; ++j)
- ttm_pool_type_fini(&pool->caching[i].orders[j]);
+ drm_page_pool_destroy(pool->caching[i].orders[j]);
}
#ifdef CONFIG_DEBUG_FS
-/* Count the number of pages available in a pool_type */
-static unsigned int ttm_pool_type_count(struct ttm_pool_type *pt)
-{
- unsigned int count = 0;
- struct page *p;
-
- spin_lock(&pt->lock);
- /* Only used for debugfs, the overhead doesn't matter */
- list_for_each_entry(p, &pt->pages, lru)
- ++count;
- spin_unlock(&pt->lock);
-
- return count;
-}
-
/* Dump information about the different pool types */
-static void ttm_pool_debugfs_orders(struct ttm_pool_type *pt,
+static void ttm_pool_debugfs_orders(struct drm_page_pool **pt,
struct seq_file *m)
{
unsigned int i;
for (i = 0; i < MAX_ORDER; ++i)
- seq_printf(m, " %8u", ttm_pool_type_count(&pt[i]));
+ seq_printf(m, " %8u", drm_page_pool_get_size(pt[i]));
seq_puts(m, "\n");
}
@@ -602,7 +506,10 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
}
seq_printf(m, "\ntotal\t: %8lu of %8lu\n",
- atomic_long_read(&allocated_pages), page_pool_size);
+ atomic_long_read(&allocated_pages),
+ drm_page_pool_get_max());
+ seq_printf(m, "(%8lu in non-ttm pools)\n", drm_page_pool_get_total() -
+ atomic_long_read(&allocated_pages));
mutex_unlock(&shrinker_lock);
@@ -612,28 +519,6 @@ EXPORT_SYMBOL(ttm_pool_debugfs);
#endif
-/* As long as pages are available make sure to release at least one */
-static unsigned long ttm_pool_shrinker_scan(struct shrinker *shrink,
- struct shrink_control *sc)
-{
- unsigned long num_freed = 0;
-
- do
- num_freed += ttm_pool_shrink();
- while (!num_freed && atomic_long_read(&allocated_pages));
-
- return num_freed;
-}
-
-/* Return the number of pages available or SHRINK_EMPTY if we have none */
-static unsigned long ttm_pool_shrinker_count(struct shrinker *shrink,
- struct shrink_control *sc)
-{
- unsigned long num_pages = atomic_long_read(&allocated_pages);
-
- return num_pages ? num_pages : SHRINK_EMPTY;
-}
-
/**
* ttm_pool_mgr_init - Initialize globals
*
@@ -648,24 +533,21 @@ int ttm_pool_mgr_init(unsigned long num_pages)
if (!page_pool_size)
page_pool_size = num_pages;
+ drm_page_pool_set_max(page_pool_size);
+
mutex_init(&shrinker_lock);
- INIT_LIST_HEAD(&shrinker_list);
for (i = 0; i < MAX_ORDER; ++i) {
- ttm_pool_type_init(&global_write_combined[i], NULL,
- ttm_write_combined, i);
- ttm_pool_type_init(&global_uncached[i], NULL, ttm_uncached, i);
-
- ttm_pool_type_init(&global_dma32_write_combined[i], NULL,
- ttm_write_combined, i);
- ttm_pool_type_init(&global_dma32_uncached[i], NULL,
- ttm_uncached, i);
+ global_write_combined[i] = drm_page_pool_create(i,
+ ttm_pool_free_page);
+ global_uncached[i] = drm_page_pool_create(i,
+ ttm_pool_free_page);
+ global_dma32_write_combined[i] = drm_page_pool_create(i,
+ ttm_pool_free_page);
+ global_dma32_uncached[i] = drm_page_pool_create(i,
+ ttm_pool_free_page);
}
-
- mm_shrinker.count_objects = ttm_pool_shrinker_count;
- mm_shrinker.scan_objects = ttm_pool_shrinker_scan;
- mm_shrinker.seeks = 1;
- return register_shrinker(&mm_shrinker);
+ return 0;
}
/**
@@ -678,13 +560,10 @@ void ttm_pool_mgr_fini(void)
unsigned int i;
for (i = 0; i < MAX_ORDER; ++i) {
- ttm_pool_type_fini(&global_write_combined[i]);
- ttm_pool_type_fini(&global_uncached[i]);
+ drm_page_pool_destroy(global_write_combined[i]);
+ drm_page_pool_destroy(global_uncached[i]);
- ttm_pool_type_fini(&global_dma32_write_combined[i]);
- ttm_pool_type_fini(&global_dma32_uncached[i]);
+ drm_page_pool_destroy(global_dma32_write_combined[i]);
+ drm_page_pool_destroy(global_dma32_uncached[i]);
}
-
- unregister_shrinker(&mm_shrinker);
- WARN_ON(!list_empty(&shrinker_list));
}
diff --git a/include/drm/ttm/ttm_pool.h b/include/drm/ttm/ttm_pool.h
index 4321728bdd11..460ab232fd22 100644
--- a/include/drm/ttm/ttm_pool.h
+++ b/include/drm/ttm/ttm_pool.h
@@ -36,27 +36,6 @@ struct ttm_tt;
struct ttm_pool;
struct ttm_operation_ctx;
-/**
- * ttm_pool_type - Pool for a certain memory type
- *
- * @pool: the pool we belong to, might be NULL for the global ones
- * @order: the allocation order our pages have
- * @caching: the caching type our pages have
- * @shrinker_list: our place on the global shrinker list
- * @lock: protection of the page list
- * @pages: the list of pages in the pool
- */
-struct ttm_pool_type {
- struct ttm_pool *pool;
- unsigned int order;
- enum ttm_caching caching;
-
- struct list_head shrinker_list;
-
- spinlock_t lock;
- struct list_head pages;
-};
-
/**
* ttm_pool - Pool for all caching and orders
*
@@ -71,7 +50,7 @@ struct ttm_pool {
bool use_dma32;
struct {
- struct ttm_pool_type orders[MAX_ORDER];
+ struct drm_page_pool *orders[MAX_ORDER];
} caching[TTM_NUM_CACHING_TYPES];
};