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authorVineet Gupta <Vineet.Gupta1@synopsys.com>2013-09-04 17:17:15 +0530
committerDavid S. Miller <davem@davemloft.net>2013-09-05 14:25:10 -0400
commit27082ee1b92f4d41e78b85fe40f6ab39673fba00 (patch)
treef71d1548ade88d3f1484f59aca8fb04ec2524679
parent7bf6630523a4fddcc3e37bc37dadbe0cf2362354 (diff)
ethernet/arc/arc_emac: Fix huge delays in large file copies
copying large files to a NFS mounted host was taking absurdly large time. Turns out that TX BD reclaim had a sublte bug. Loop starts off from @txbd_dirty cursor and stops when it hits a BD still in use by controller. However when it stops it needs to keep the cursor at that very BD to resume scanning in next iteration. However it was erroneously incrementing the cursor, causing the next scan(s) to fail too, unless the BD chain was completely drained out. [ARCLinux]$ ls -l -sh /disk/log.txt 17976 -rw-r--r-- 1 root root 17.5M Sep /disk/log.txt ========== Before ===================== [ARCLinux]$ time cp /disk/log.txt /mnt/. real 31m 7.95s user 0m 0.00s sys 0m 0.10s ========== After ===================== [ARCLinux]$ time cp /disk/log.txt /mnt/. real 0m 24.33s user 0m 0.00s sys 0m 0.19s Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Alexey Brodkin <abrodkin@synopsys.com> (commit_signer:3/4=75%) Cc: "David S. Miller" <davem@davemloft.net> (commit_signer:3/4=75%) Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: arc-linux-dev@synopsys.com Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/ethernet/arc/emac_main.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index 55d79cb53a7..9e160148726 100644
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -149,8 +149,6 @@ static void arc_emac_tx_clean(struct net_device *ndev)
struct sk_buff *skb = tx_buff->skb;
unsigned int info = le32_to_cpu(txbd->info);
- *txbd_dirty = (*txbd_dirty + 1) % TX_BD_NUM;
-
if ((info & FOR_EMAC) || !txbd->data)
break;
@@ -180,6 +178,8 @@ static void arc_emac_tx_clean(struct net_device *ndev)
txbd->data = 0;
txbd->info = 0;
+ *txbd_dirty = (*txbd_dirty + 1) % TX_BD_NUM;
+
if (netif_queue_stopped(ndev))
netif_wake_queue(ndev);
}