From f7251a9ce936f1006fbfdef63dbe42ae5e0fee7c Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Thu, 17 May 2012 18:40:54 +0100 Subject: sfc: Simplify TSO header buffer allocation TSO header buffers contain a control structure immediately followed by the packet headers, and are kept on a free list when not in use. This complicates buffer management and tends to result in cache read misses when we recycle such buffers (particularly if DMA-coherent memory requires caches to be disabled). Replace the free list with a simple mapping by descriptor index. We know that there is always a payload descriptor between any two descriptors with TSO header buffers, so we can allocate only one such buffer for each two descriptors. While we're at it, use a standard error code for allocation failure, not -1. Signed-off-by: Ben Hutchings --- drivers/net/ethernet/sfc/net_driver.h | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'drivers/net/ethernet/sfc/net_driver.h') diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h index 28a6d6258692..a4fe9a786ef8 100644 --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -94,7 +94,8 @@ struct efx_special_buffer { * struct efx_tx_buffer - buffer state for a TX descriptor * @skb: When @flags & %EFX_TX_BUF_SKB, the associated socket buffer to be * freed when descriptor completes - * @tsoh: When @flags & %EFX_TX_BUF_TSOH, the associated TSO header structure. + * @heap_buf: When @flags & %EFX_TX_BUF_HEAP, the associated heap buffer to be + * freed when descriptor completes. * @dma_addr: DMA address of the fragment. * @flags: Flags for allocation and DMA mapping type * @len: Length of this fragment. @@ -104,7 +105,7 @@ struct efx_special_buffer { struct efx_tx_buffer { union { const struct sk_buff *skb; - struct efx_tso_header *tsoh; + void *heap_buf; }; dma_addr_t dma_addr; unsigned short flags; @@ -113,7 +114,7 @@ struct efx_tx_buffer { }; #define EFX_TX_BUF_CONT 1 /* not last descriptor of packet */ #define EFX_TX_BUF_SKB 2 /* buffer is last part of skb */ -#define EFX_TX_BUF_TSOH 4 /* buffer is TSO header */ +#define EFX_TX_BUF_HEAP 4 /* buffer was allocated with kmalloc() */ #define EFX_TX_BUF_MAP_SINGLE 8 /* buffer was mapped with dma_map_single() */ /** @@ -134,6 +135,7 @@ struct efx_tx_buffer { * @channel: The associated channel * @core_txq: The networking core TX queue structure * @buffer: The software buffer ring + * @tsoh_page: Array of pages of TSO header buffers * @txd: The hardware descriptor ring * @ptr_mask: The size of the ring minus 1. * @initialised: Has hardware queue been initialised? @@ -157,9 +159,6 @@ struct efx_tx_buffer { * variable indicates that the queue is full. This is to * avoid cache-line ping-pong between the xmit path and the * completion path. - * @tso_headers_free: A list of TSO headers allocated for this TX queue - * that are not in use, and so available for new TSO sends. The list - * is protected by the TX queue lock. * @tso_bursts: Number of times TSO xmit invoked by kernel * @tso_long_headers: Number of packets with headers too long for standard * blocks @@ -176,6 +175,7 @@ struct efx_tx_queue { struct efx_channel *channel; struct netdev_queue *core_txq; struct efx_tx_buffer *buffer; + struct efx_buffer *tsoh_page; struct efx_special_buffer txd; unsigned int ptr_mask; bool initialised; @@ -188,7 +188,6 @@ struct efx_tx_queue { unsigned int insert_count ____cacheline_aligned_in_smp; unsigned int write_count; unsigned int old_read_count; - struct efx_tso_header *tso_headers_free; unsigned int tso_bursts; unsigned int tso_long_headers; unsigned int tso_packets; -- cgit v1.2.3-55-g7522