On Wed, Jul 08, 2015 at 02:16:37PM -0400, j.glisse at gmail.com wrote:
> From: Jérôme Glisse <jglisse at redhat.com>
>
> Calls to set_memory_wb() incure heavy TLB flush and IPI cost. To
> minimize those wait until pool grow beyond batch size before
> draining the pool.
>
> Signed-off-by: Jérôme Glisse <jglisse at redhat.com>
> Reviewed-by: Mario Kleiner <mario.kleiner.de at gmail.com>
> Cc: Michel Dänzer <michel at daenzer.net>
> Cc: Thomas Hellstrom <thellstrom at vmware.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
> ---
> drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> index 0194a93..8028dd6 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
> @@ -953,7 +953,12 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma,
> struct device *dev)
> } else {
> pool->npages_free += count;
> list_splice(&ttm_dma->pages_list, &pool->free_list);
> - if (pool->npages_free > _manager->options.max_size)
> + /*
> + * Wait to have at at least NUM_PAGES_TO_ALLOC number of pages
> + * to free in order to minimize calls to set_memory_wb().
> + */
> + if (pool->npages_free >= (_manager->options.max_size +
> + NUM_PAGES_TO_ALLOC))
> npages = pool->npages_free - _manager->options.max_size;
> }
> spin_unlock_irqrestore(&pool->lock, irq_flags);
> --
> 1.8.3.1
>
