[PATCH] s390: lcs performance enhancements

[patch 1/2] s390: lcs performance enhancements

From: Klaus Wacker <kdwacker@de.ibm.com>
	- When flood pinging (with large packet size) an LCS device,
	  about 90 % of all packets are dropped by driver.
	- increased number of lcs IO buffers to 32.
	- use netif_stop_queue/netif_wake_queue in lcs_start_xmit routine
	- don't lock the whole xmit routine but just the piece of code where
	  tx_buffer is touched.

Signed-off-by: Frank Pavlic <fpavlic@de.ibm.com>
diffstat:
 lcs.c |   31 +++++++++++++++++--------------
 lcs.h |    2 +-
 2 files changed, 18 insertions(+), 15 deletions(-)
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c
index 6229ba4..9cf88d7 100644 (file)
--- a/drivers/s390/net/lcs.c
+++ b/drivers/s390/net/lcs.c
@@ -98,9 +98,9 @@ lcs_register_debug_facility(void)
                return -ENOMEM;
        }
        debug_register_view(lcs_dbf_setup, &debug_hex_ascii_view);
-       debug_set_level(lcs_dbf_setup, 4);
+       debug_set_level(lcs_dbf_setup, 2);
        debug_register_view(lcs_dbf_trace, &debug_hex_ascii_view);
-       debug_set_level(lcs_dbf_trace, 4);
+       debug_set_level(lcs_dbf_trace, 2);
        return 0;
 }
 
@@ -1292,9 +1292,8 @@ lcs_set_multicast_list(struct net_device *dev)
         LCS_DBF_TEXT(4, trace, "setmulti");
         card = (struct lcs_card *) dev->priv;
 
-        if (!lcs_set_thread_start_bit(card, LCS_SET_MC_THREAD)) {
+        if (!lcs_set_thread_start_bit(card, LCS_SET_MC_THREAD)) 
                schedule_work(&card->kernel_thread_starter);
-       }
 }
 
 #endif /* CONFIG_IP_MULTICAST */
@@ -1459,6 +1458,8 @@ lcs_txbuffer_cb(struct lcs_channel *channel, struct lcs_buffer *buffer)
        lcs_release_buffer(channel, buffer);
        card = (struct lcs_card *)
                ((char *) channel - offsetof(struct lcs_card, write));
+       if (netif_queue_stopped(card->dev))
+               netif_wake_queue(card->dev);
        spin_lock(&card->lock);
        card->tx_emitted--;
        if (card->tx_emitted <= 0 && card->tx_buffer != NULL)
@@ -1478,6 +1479,7 @@ __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb,
                 struct net_device *dev)
 {
        struct lcs_header *header;
+       int rc = 0;
 
        LCS_DBF_TEXT(5, trace, "hardxmit");
        if (skb == NULL) {
@@ -1492,10 +1494,8 @@ __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb,
                card->stats.tx_carrier_errors++;
                return 0;
        }
-       if (netif_queue_stopped(dev) ) {
-               card->stats.tx_dropped++;
-               return -EBUSY;
-       }
+       netif_stop_queue(card->dev);
+       spin_lock(&card->lock);
        if (card->tx_buffer != NULL &&
            card->tx_buffer->count + sizeof(struct lcs_header) +
            skb->len + sizeof(u16) > LCS_IOBUFFERSIZE)
@@ -1506,7 +1506,8 @@ __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb,
                card->tx_buffer = lcs_get_buffer(&card->write);
                if (card->tx_buffer == NULL) {
                        card->stats.tx_dropped++;
-                       return -EBUSY;
+                       rc = -EBUSY;
+                       goto out;
                }
                card->tx_buffer->callback = lcs_txbuffer_cb;
                card->tx_buffer->count = 0;
@@ -1518,13 +1519,18 @@ __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb,
        header->type = card->lan_type;
        header->slot = card->portno;
        memcpy(header + 1, skb->data, skb->len);
+       spin_unlock(&card->lock);
        card->stats.tx_bytes += skb->len;
        card->stats.tx_packets++;
        dev_kfree_skb(skb);
-       if (card->tx_emitted <= 0)
+       netif_wake_queue(card->dev);
+       spin_lock(&card->lock);
+       if (card->tx_emitted <= 0 && card->tx_buffer != NULL)
                /* If this is the first tx buffer emit it immediately. */
                __lcs_emit_txbuffer(card);
-       return 0;
+out:
+       spin_unlock(&card->lock);
+       return rc;
 }
 
 static int
@@ -1535,9 +1541,7 @@ lcs_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
        LCS_DBF_TEXT(5, trace, "pktxmit");
        card = (struct lcs_card *) dev->priv;
-       spin_lock(&card->lock);
        rc = __lcs_start_xmit(card, skb, dev);
-       spin_unlock(&card->lock);
        return rc;
 }
 
@@ -2319,7 +2323,6 @@ __init lcs_init_module(void)
                PRINT_ERR("Initialization failed\n");
                return rc;
        }
-
        return 0;
 }
 

diff --git a/drivers/s390/net/lcs.h b/drivers/s390/net/lcs.h
index 08e60ad..2fad5e4 100644 (file)
--- a/drivers/s390/net/lcs.h
+++ b/drivers/s390/net/lcs.h
@@ -95,7 +95,7 @@ do {                                       \
  */
 #define LCS_ILLEGAL_OFFSET             0xffff
 #define LCS_IOBUFFERSIZE               0x5000
-#define LCS_NUM_BUFFS                  8       /* needs to be power of 2 */
+#define LCS_NUM_BUFFS                  32      /* needs to be power of 2 */
 #define LCS_MAC_LENGTH                 6
 #define LCS_INVALID_PORT_NO            -1
 #define LCS_LANCMD_TIMEOUT_DEFAULT      5