linux-kernel - Re: [PATCH 1/2] drm/ttm: Add TTM_PAGE_FLAG

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Message-ID: <a77d7229-e8f7-83bf-2098-8db07cebb117@amd.com>
Date:   Fri, 27 Apr 2018 10:51:05 +0800
From:   zhoucm1 <zhoucm1@....com>
To:     Michel Dänzer <michel@...nzer.net>,
        Christian König <christian.koenig@....com>,
        Roger He <Hongbo.He@....com>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] drm/ttm: Add TTM_PAGE_FLAG_TRANSHUGE



On 2018年04月26日 23:06, Michel Dänzer wrote:
> From: Michel Dänzer <michel.daenzer@....com>
>
> When it's set, TTM tries to allocate huge pages if possible.
Do you mean original driver doesn't do this?
 From the code, driver always try huge pages if 
CONFIG_TRANSPARENT_HUGEPAGE is enabled.

Regards,
David Zhou
>   Drivers
> which can take advantage of huge pages should set it.
>
> Drivers not setting this flag no longer incur any overhead related to
> allocating or freeing huge pages.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Michel Dänzer <michel.daenzer@....com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c  |  2 +-
>   drivers/gpu/drm/ttm/ttm_page_alloc.c     | 14 ++++++++++----
>   drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |  8 +++++---
>   include/drm/ttm/ttm_tt.h                 |  1 +
>   4 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index dfd22db13fb1..e03e9e361e2a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -988,7 +988,7 @@ static struct ttm_tt *amdgpu_ttm_tt_create(struct ttm_buffer_object *bo,
>   		return NULL;
>   	}
>   	gtt->ttm.ttm.func = &amdgpu_backend_func;
> -	if (ttm_sg_tt_init(&gtt->ttm, bo, page_flags)) {
> +	if (ttm_sg_tt_init(&gtt->ttm, bo, page_flags | TTM_PAGE_FLAG_TRANSHUGE)) {
>   		kfree(gtt);
>   		return NULL;
>   	}
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index f0481b7b60c5..2ce91272b111 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -760,7 +760,7 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags,
>   {
>   	struct ttm_page_pool *pool = ttm_get_pool(flags, false, cstate);
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -	struct ttm_page_pool *huge = ttm_get_pool(flags, true, cstate);
> +	struct ttm_page_pool *huge = NULL;
>   #endif
>   	unsigned long irq_flags;
>   	unsigned i;
> @@ -780,7 +780,8 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags,
>   			}
>   
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -			if (!(flags & TTM_PAGE_FLAG_DMA32)) {
> +			if ((flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE)) ==
> +			    TTM_PAGE_FLAG_TRANSHUGE) {
>   				for (j = 0; j < HPAGE_PMD_NR; ++j)
>   					if (p++ != pages[i + j])
>   					    break;
> @@ -805,6 +806,8 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags,
>   
>   	i = 0;
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +	if (flags & TTM_PAGE_FLAG_TRANSHUGE)
> +		huge = ttm_get_pool(flags, true, cstate);
>   	if (huge) {
>   		unsigned max_size, n2free;
>   
> @@ -877,7 +880,7 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
>   {
>   	struct ttm_page_pool *pool = ttm_get_pool(flags, false, cstate);
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -	struct ttm_page_pool *huge = ttm_get_pool(flags, true, cstate);
> +	struct ttm_page_pool *huge = NULL;
>   #endif
>   	struct list_head plist;
>   	struct page *p = NULL;
> @@ -906,7 +909,8 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
>   
>   		i = 0;
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -		if (!(gfp_flags & GFP_DMA32)) {
> +		if ((flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE)) ==
> +		    TTM_PAGE_FLAG_TRANSHUGE) {
>   			while (npages >= HPAGE_PMD_NR) {
>   				gfp_t huge_flags = gfp_flags;
>   
> @@ -946,6 +950,8 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
>   	count = 0;
>   
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +	if (flags & TTM_PAGE_FLAG_TRANSHUGE)
> +		huge = ttm_get_pool(flags, true, cstate);
>   	if (huge && npages >= HPAGE_PMD_NR) {
>   		INIT_LIST_HEAD(&plist);
>   		ttm_page_pool_get_pages(huge, &plist, flags, cstate,
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> index 8a25d1974385..291b04213ec5 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> @@ -949,7 +949,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
>   	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
>   
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -	if (ttm->page_flags & TTM_PAGE_FLAG_DMA32)
> +	if ((ttm->page_flags & (TTM_PAGE_FLAG_DMA32 | TTM_PAGE_FLAG_TRANSHUGE))
> +	    != TTM_PAGE_FLAG_TRANSHUGE)
>   		goto skip_huge;
>   
>   	pool = ttm_dma_find_pool(dev, type | IS_HUGE);
> @@ -1035,7 +1036,7 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
>   {
>   	struct ttm_tt *ttm = &ttm_dma->ttm;
>   	struct ttm_mem_global *mem_glob = ttm->bdev->glob->mem_glob;
> -	struct dma_pool *pool;
> +	struct dma_pool *pool = NULL;
>   	struct dma_page *d_page, *next;
>   	enum pool_type type;
>   	bool is_cached = false;
> @@ -1045,7 +1046,8 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
>   	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
>   
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -	pool = ttm_dma_find_pool(dev, type | IS_HUGE);
> +	if (ttm->page_flags & TTM_PAGE_FLAG_TRANSHUGE)
> +		pool = ttm_dma_find_pool(dev, type | IS_HUGE);
>   	if (pool) {
>   		count = 0;
>   		list_for_each_entry_safe(d_page, next, &ttm_dma->pages_list,
> diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
> index c0e928abf592..c7d2120f0362 100644
> --- a/include/drm/ttm/ttm_tt.h
> +++ b/include/drm/ttm/ttm_tt.h
> @@ -41,6 +41,7 @@ struct ttm_operation_ctx;
>   #define TTM_PAGE_FLAG_DMA32           (1 << 7)
>   #define TTM_PAGE_FLAG_SG              (1 << 8)
>   #define TTM_PAGE_FLAG_NO_RETRY	      (1 << 9)
> +#define TTM_PAGE_FLAG_TRANSHUGE       (1 << 10)
>   
>   enum ttm_caching_state {
>   	tt_uncached,