From bd4171a5d4c2827f4ae7a235389648d7c149a41b Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Wed, 14 Dec 2016 15:05:34 -0800 Subject: [PATCH] igb: update code to better handle incrementing page count Update the driver code so that we do bulk updates of the page reference count instead of just incrementing it by one reference at a time. The advantage to doing this is that we cut down on atomic operations and this in turn should give us a slight improvement in cycles per packet. In addition if we eventually move this over to using build_skb the gains will be more noticeable. Link: http://lkml.kernel.org/r/20161110113616.76501.17072.stgit@ahduyck-blue-test.jf.intel.com Signed-off-by: Alexander Duyck Acked-by: Jeff Kirsher Cc: "David S. Miller" Cc: "James E.J. Bottomley" Cc: Chris Metcalf Cc: David Howells Cc: Geert Uytterhoeven Cc: Hans-Christian Noren Egtvedt Cc: Helge Deller Cc: James Hogan Cc: Jonas Bonn Cc: Keguang Zhang Cc: Ley Foon Tan Cc: Mark Salter Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Ralf Baechle Cc: Rich Felker Cc: Richard Kuo Cc: Russell King Cc: Steven Miao Cc: Tobias Klauser Cc: Vineet Gupta Cc: Yoshinori Sato Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/net/ethernet/intel/igb/igb.h | 7 ++++++- drivers/net/ethernet/intel/igb/igb_main.c | 24 +++++++++++++++++------- 2 files changed, 23 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h index d11093d..acbc3ab 100644 --- a/drivers/net/ethernet/intel/igb/igb.h +++ b/drivers/net/ethernet/intel/igb/igb.h @@ -210,7 +210,12 @@ struct igb_tx_buffer { struct igb_rx_buffer { dma_addr_t dma; struct page *page; - unsigned int page_offset; +#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536) + __u32 page_offset; +#else + __u16 page_offset; +#endif + __u16 pagecnt_bias; }; struct igb_tx_queue_stats { diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index 60f1225..a761001 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -3962,7 +3962,8 @@ static void igb_clean_rx_ring(struct igb_ring *rx_ring) PAGE_SIZE, DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC); - __free_page(buffer_info->page); + __page_frag_drain(buffer_info->page, 0, + buffer_info->pagecnt_bias); buffer_info->page = NULL; } @@ -6834,13 +6835,15 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer, struct page *page, unsigned int truesize) { + unsigned int pagecnt_bias = rx_buffer->pagecnt_bias--; + /* avoid re-using remote pages */ if (unlikely(igb_page_is_reserved(page))) return false; #if (PAGE_SIZE < 8192) /* if we are only owner of page we can reuse it */ - if (unlikely(page_count(page) != 1)) + if (unlikely(page_ref_count(page) != pagecnt_bias)) return false; /* flip page offset to other buffer */ @@ -6853,10 +6856,14 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer, return false; #endif - /* Even if we own the page, we are not allowed to use atomic_set() - * This would break get_page_unless_zero() users. + /* If we have drained the page fragment pool we need to update + * the pagecnt_bias and page count so that we fully restock the + * number of references the driver holds. */ - page_ref_inc(page); + if (unlikely(pagecnt_bias == 1)) { + page_ref_add(page, USHRT_MAX); + rx_buffer->pagecnt_bias = USHRT_MAX; + } return true; } @@ -6908,7 +6915,6 @@ static bool igb_add_rx_frag(struct igb_ring *rx_ring, return true; /* this page cannot be reused so discard it */ - __free_page(page); return false; } @@ -6979,10 +6985,13 @@ static struct sk_buff *igb_fetch_rx_buffer(struct igb_ring *rx_ring, /* hand second half of page back to the ring */ igb_reuse_rx_page(rx_ring, rx_buffer); } else { - /* we are not reusing the buffer so unmap it */ + /* We are not reusing the buffer so unmap it and free + * any references we are holding to it + */ dma_unmap_page_attrs(rx_ring->dev, rx_buffer->dma, PAGE_SIZE, DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC); + __page_frag_drain(page, 0, rx_buffer->pagecnt_bias); } /* clear contents of rx_buffer */ @@ -7256,6 +7265,7 @@ static bool igb_alloc_mapped_page(struct igb_ring *rx_ring, bi->dma = dma; bi->page = page; bi->page_offset = 0; + bi->pagecnt_bias = 1; return true; } -- 2.7.4