From 325ad0617adaf163e32dd2d857b90baf65a25b5b Mon Sep 17 00:00:00 2001 From: Guy Shapiro Date: Wed, 15 Apr 2015 18:17:57 +0300 Subject: [PATCH] IB/core: dma unmap optimizations While unmapping an ODP writable page, the dirty bit of the page is set. In order to do so, the head of the compound page is found. Currently, the compound head is found even on non-writable pages, where it is never used, leading to unnecessary cpu barrier that impacts performance. This patch moves the search for the compound head to be done only when needed. Signed-off-by: Guy Shapiro Acked-by: Shachar Raindel Reviewed-by: Sagi Grimberg Signed-off-by: Doug Ledford --- drivers/infiniband/core/umem_odp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index aba47398880d..40becdb3196e 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -637,7 +637,6 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 virt, idx = (addr - ib_umem_start(umem)) / PAGE_SIZE; if (umem->odp_data->page_list[idx]) { struct page *page = umem->odp_data->page_list[idx]; - struct page *head_page = compound_head(page); dma_addr_t dma = umem->odp_data->dma_list[idx]; dma_addr_t dma_addr = dma & ODP_DMA_ADDR_MASK; @@ -645,7 +644,8 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 virt, ib_dma_unmap_page(dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL); - if (dma & ODP_WRITE_ALLOWED_BIT) + if (dma & ODP_WRITE_ALLOWED_BIT) { + struct page *head_page = compound_head(page); /* * set_page_dirty prefers being called with * the page lock. However, MMU notifiers are @@ -656,6 +656,7 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 virt, * be removed. */ set_page_dirty(head_page); + } /* on demand pinning support */ if (!umem->context->invalidate_range) put_page(page); -- 2.20.1