Re: [PATCH 11/12] drm/vmwgfx: Remove usage of MOBFMT_RANGE

On Mon, 2021-12-06 at 12:26 -0500, Zack Rusin wrote:

From: Zack Rusin zackr@vmware.com

Using MOBFMT_RANGE in the early days of guest backed objects was a major performance win but that has changed a lot since. There's no more a performance reason to use MOBFMT_RANGE. The device can/will still profit from the pages being contiguous but marking them as MOBFMT_RANGE no longer matters. Benchmarks (e.g. heaven, valley) show that creating page tables for mob memory is actually faster than using mobfmt ranges.

Signed-off-by: Zack Rusin zackr@vmware.com

drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 1 - drivers/gpu/drm/vmwgfx/vmwgfx_mob.c | 6 ------ drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c | 12 ------------ 3 files changed, 19 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index 21dd69e5cdfb..1760ba1b0d4a 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -333,7 +333,6 @@ struct vmw_sg_table { struct page **pages; const dma_addr_t *addrs; struct sg_table *sgt;

• unsigned long num_regions; unsigned long num_pages;

};

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c index 65f7c2bdc322..2d91a44a3b22 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c @@ -146,9 +146,6 @@ static int vmw_setup_otable_base(struct vmw_private *dev_priv, if (otable->size <= PAGE_SIZE) { mob->pt_level = VMW_MOBFMT_PTDEPTH_0; mob->pt_root_page = vmw_piter_dma_addr(&iter);

• } else if (vsgt->num_regions == 1) {

• mob->pt_level = SVGA3D_MOBFMT_RANGE;
  

• mob->pt_root_page = vmw_piter_dma_addr(&iter);
  

  } else { ret = vmw_mob_pt_populate(dev_priv, mob); if (unlikely(ret != 0))

@@ -623,9 +620,6 @@ int vmw_mob_bind(struct vmw_private *dev_priv, if (likely(num_data_pages == 1)) { mob->pt_level = VMW_MOBFMT_PTDEPTH_0; mob->pt_root_page = vmw_piter_dma_addr(&data_iter);

• } else if (vsgt->num_regions == 1) {

• mob->pt_level = SVGA3D_MOBFMT_RANGE;
  

• mob->pt_root_page = vmw_piter_dma_addr(&data_iter);
  

  } else if (unlikely(mob->pt_bo == NULL)) { ret = vmw_mob_pt_populate(dev_priv, mob); if (unlikely(ret != 0))

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c index 20f752ff6168..b84ecc6d6611 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c @@ -288,8 +288,6 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt) { struct vmw_private *dev_priv = vmw_tt->dev_priv; struct vmw_sg_table *vsgt = &vmw_tt->vsgt;

• struct vmw_piter iter;

• dma_addr_t old; int ret = 0;

  if (vmw_tt->mapped)

@@ -321,16 +319,6 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt) break; }

• old = ~((dma_addr_t) 0);
• vmw_tt->vsgt.num_regions = 0;
• for (vmw_piter_start(&iter, vsgt, 0); vmw_piter_next(&iter);) {

• dma_addr_t cur = vmw_piter_dma_addr(&iter);
  

• if (cur != old + PAGE_SIZE)
  

• 	vmw_tt->vsgt.num_regions++;
  

• old = cur;
  

• }
• vmw_tt->mapped = true; return 0;

Reviewed-by: Martin Krastev krastevm@vmware.com