From ad5da10a64bdca1ed39b25946727a1ce2659f3d4 Mon Sep 17 00:00:00 2001 From: Olof Johansson Date: Tue, 2 Oct 2007 16:27:15 -0500 Subject: [PATCH] pasemi_mac: further performance tweaks pasemi_mac: further performance tweaks Misc driver tweaks for pasemi_mac: * Increase ring size (really needed mostly on 10G) * Take out an unneeded barrier * Move around a few prefetches and reorder a few calls * Don't try to clean on full tx buffer, just let things take their course and stop the queue directly * Avoid filling on the same line as the interface is working on to reduce cache line bouncing * Avoid unneeded clearing of software state (and make the interface shutdown code handle it) * Fix up some of the tx ring wrap logic. Signed-off-by: Olof Johansson Signed-off-by: Jeff Garzik --- drivers/net/pasemi_mac.c | 92 ++++++++++++++++++++-------------------- 1 file changed, 47 insertions(+), 45 deletions(-) diff --git a/drivers/net/pasemi_mac.c b/drivers/net/pasemi_mac.c index b3994f5d2d2b..4a451f8c6f4d 100644 --- a/drivers/net/pasemi_mac.c +++ b/drivers/net/pasemi_mac.c @@ -56,8 +56,8 @@ /* Must be a power of two */ -#define RX_RING_SIZE 512 -#define TX_RING_SIZE 512 +#define RX_RING_SIZE 4096 +#define TX_RING_SIZE 4096 #define DEFAULT_MSG_ENABLE \ (NETIF_MSG_DRV | \ @@ -336,8 +336,16 @@ static void pasemi_mac_free_tx_resources(struct net_device *dev) struct pasemi_mac_buffer *info; dma_addr_t dmas[MAX_SKB_FRAGS+1]; int freed; + int start, limit; - for (i = 0; i < TX_RING_SIZE; i += freed) { + start = mac->tx->next_to_clean; + limit = mac->tx->next_to_fill; + + /* Compensate for when fill has wrapped and clean has not */ + if (start > limit) + limit += TX_RING_SIZE; + + for (i = start; i < limit; i += freed) { info = &TX_RING_INFO(mac, i+1); if (info->dma && info->skb) { for (j = 0; j <= skb_shinfo(info->skb)->nr_frags; j++) @@ -520,9 +528,6 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit) n = mac->rx->next_to_clean; for (count = limit; count; count--) { - - rmb(); - macrx = RX_RING(mac, n); if ((macrx & XCT_MACRX_E) || @@ -550,14 +555,10 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit) break; } - prefetchw(info); - skb = info->skb; - prefetchw(skb); - info->dma = 0; - pci_unmap_single(mac->dma_pdev, dma, skb->len, - PCI_DMA_FROMDEVICE); + prefetch(skb); + prefetch(&skb->data_len); len = (macrx & XCT_MACRX_LLEN_M) >> XCT_MACRX_LLEN_S; @@ -576,10 +577,9 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit) } else info->skb = NULL; - /* Need to zero it out since hardware doesn't, since the - * replenish loop uses it to tell when it's done. - */ - RX_BUFF(mac, i) = 0; + pci_unmap_single(mac->dma_pdev, dma, len, PCI_DMA_FROMDEVICE); + + info->dma = 0; skb_put(skb, len); @@ -599,6 +599,11 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit) RX_RING(mac, n) = 0; RX_RING(mac, n+1) = 0; + /* Need to zero it out since hardware doesn't, since the + * replenish loop uses it to tell when it's done. + */ + RX_BUFF(mac, i) = 0; + n += 2; } @@ -621,27 +626,33 @@ static int pasemi_mac_clean_rx(struct pasemi_mac *mac, int limit) static int pasemi_mac_clean_tx(struct pasemi_mac *mac) { int i, j; - struct pasemi_mac_buffer *info; - unsigned int start, descr_count, buf_count, limit; + unsigned int start, descr_count, buf_count, batch_limit; + unsigned int ring_limit; unsigned int total_count; unsigned long flags; struct sk_buff *skbs[TX_CLEAN_BATCHSIZE]; dma_addr_t dmas[TX_CLEAN_BATCHSIZE][MAX_SKB_FRAGS+1]; total_count = 0; - limit = TX_CLEAN_BATCHSIZE; + batch_limit = TX_CLEAN_BATCHSIZE; restart: spin_lock_irqsave(&mac->tx->lock, flags); start = mac->tx->next_to_clean; + ring_limit = mac->tx->next_to_fill; + + /* Compensate for when fill has wrapped but clean has not */ + if (start > ring_limit) + ring_limit += TX_RING_SIZE; buf_count = 0; descr_count = 0; for (i = start; - descr_count < limit && i < mac->tx->next_to_fill; + descr_count < batch_limit && i < ring_limit; i += buf_count) { u64 mactx = TX_RING(mac, i); + struct sk_buff *skb; if ((mactx & XCT_MACTX_E) || (*mac->tx_status & PAS_STATUS_ERROR)) @@ -651,19 +662,15 @@ restart: /* Not yet transmitted */ break; - info = &TX_RING_INFO(mac, i+1); - skbs[descr_count] = info->skb; + skb = TX_RING_INFO(mac, i+1).skb; + skbs[descr_count] = skb; - buf_count = 2 + skb_shinfo(info->skb)->nr_frags; - for (j = 0; j <= skb_shinfo(info->skb)->nr_frags; j++) + buf_count = 2 + skb_shinfo(skb)->nr_frags; + for (j = 0; j <= skb_shinfo(skb)->nr_frags; j++) dmas[descr_count][j] = TX_RING_INFO(mac, i+1+j).dma; - - info->dma = 0; TX_RING(mac, i) = 0; TX_RING(mac, i+1) = 0; - TX_RING_INFO(mac, i+1).skb = 0; - TX_RING_INFO(mac, i+1).dma = 0; /* Since we always fill with an even number of entries, make * sure we skip any unused one at the end as well. @@ -672,7 +679,7 @@ restart: buf_count++; descr_count++; } - mac->tx->next_to_clean = i; + mac->tx->next_to_clean = i & (TX_RING_SIZE-1); spin_unlock_irqrestore(&mac->tx->lock, flags); netif_wake_queue(mac->netdev); @@ -683,7 +690,7 @@ restart: total_count += descr_count; /* If the batch was full, try to clean more */ - if (descr_count == limit) + if (descr_count == batch_limit) goto restart; return total_count; @@ -1106,19 +1113,14 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev) spin_lock_irqsave(&txring->lock, flags); - if (RING_AVAIL(txring) <= nfrags+3) { - spin_unlock_irqrestore(&txring->lock, flags); - pasemi_mac_clean_tx(mac); - pasemi_mac_restart_tx_intr(mac); - spin_lock_irqsave(&txring->lock, flags); - - if (RING_AVAIL(txring) <= nfrags+3) { - /* Still no room -- stop the queue and wait for tx - * intr when there's room. - */ - netif_stop_queue(dev); - goto out_err; - } + /* Avoid stepping on the same cache line that the DMA controller + * is currently about to send, so leave at least 8 words available. + * Total free space needed is mactx + fragments + 8 + */ + if (RING_AVAIL(txring) < nfrags + 10) { + /* no room -- stop the queue and wait for tx intr */ + netif_stop_queue(dev); + goto out_err; } TX_RING(mac, txring->next_to_fill) = mactx; @@ -1137,8 +1139,8 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev) if (nfrags & 1) nfrags++; - txring->next_to_fill += nfrags + 1; - + txring->next_to_fill = (txring->next_to_fill + nfrags + 1) & + (TX_RING_SIZE-1); dev->stats.tx_packets++; dev->stats.tx_bytes += skb->len; -- 2.20.1