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igb: update code to better handle incrementing page count

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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 <alexander.h.duyck@intel.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Helge Deller <deller@gmx.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Keguang Zhang <keguang.zhang@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexander Duyck 2016-12-14 15:05:34 -08:00 committed by Linus Torvalds
parent 5be5955425
commit bd4171a5d4
2 changed files with 23 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/net/ethernet/intel/igb/igb.h
View File

@ -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 {

24
drivers/net/ethernet/intel/igb/igb_main.c
View File

@ -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;
}