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SubjectRe: [RFC][PATCH v6 4/7] drm: ttm_pool: Rework ttm_pool to use drm_page_pool
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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@ffwll.ch>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Liam Mark <lmark@codeaurora.org>
> Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
> Cc: Laura Abbott <labbott@kernel.org>
> Cc: Brian Starkey <Brian.Starkey@arm.com>
> Cc: Hridya Valsaraju <hridya@google.com>
> Cc: Suren Baghdasaryan <surenb@google.com>
> Cc: Sandeep Patil <sspatil@google.com>
> Cc: Daniel Mentz <danielmentz@google.com>
> Cc: Ørjan Eide <orjan.eide@arm.com>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Ezequiel Garcia <ezequiel@collabora.com>
> Cc: Simon Ser <contact@emersion.fr>
> Cc: James Jones <jajones@nvidia.com>
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> 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];
> };
>

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