From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next-2.6] loopback: Implement 64bit stats on 32bit arches Date: Mon, 14 Jun 2010 17:59:22 +0200 Message-ID: <1276531162.2478.121.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Ben Hutchings To: David Miller Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:44503 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751401Ab0FNP71 (ORCPT ); Mon, 14 Jun 2010 11:59:27 -0400 Received: by wyb40 with SMTP id 40so3996307wyb.19 for ; Mon, 14 Jun 2010 08:59:25 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: Uses a seqcount_t to synchronize stat producer and consumer, for packets and bytes counter, now u64 types. (dropped counter being rarely used, stay a native "unsigned long" type) No noticeable performance impact on x86, as it only adds two increments per frame. It might be more expensive on arches where smp_wmb() is not free. Signed-off-by: Eric Dumazet --- drivers/net/loopback.c | 61 ++++++++++++++++++++++++++++++++------- 1 file changed, 51 insertions(+), 10 deletions(-) diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 72b7949..09334f8 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -60,11 +60,51 @@ #include struct pcpu_lstats { - unsigned long packets; - unsigned long bytes; + u64 packets; + u64 bytes; +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + seqcount_t seq; +#endif unsigned long drops; }; +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) +static void inline lstats_update_begin(struct pcpu_lstats *lstats) +{ + write_seqcount_begin(&lstats->seq); +} +static void inline lstats_update_end(struct pcpu_lstats *lstats) +{ + write_seqcount_end(&lstats->seq); +} +static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats) +{ + u64 tpackets, tbytes; + unsigned int seq; + + do { + seq = read_seqcount_begin(&lstats->seq); + tpackets = lstats->packets; + tbytes = lstats->bytes; + } while (read_seqcount_retry(&lstats->seq, seq)); + + *packets += tpackets; + *bytes += tbytes; +} +#else +static void inline lstats_update_begin(struct pcpu_lstats *lstats) +{ +} +static void inline lstats_update_end(struct pcpu_lstats *lstats) +{ +} +static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats) +{ + *packets += lstats->packets; + *bytes += lstats->bytes; +} +#endif + /* * The higher levels take care of making this non-reentrant (it's * called with bh's disabled). @@ -86,21 +126,23 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb, len = skb->len; if (likely(netif_rx(skb) == NET_RX_SUCCESS)) { + lstats_update_begin(lb_stats); lb_stats->bytes += len; lb_stats->packets++; + lstats_update_end(lb_stats); } else lb_stats->drops++; return NETDEV_TX_OK; } -static struct net_device_stats *loopback_get_stats(struct net_device *dev) +static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev) { const struct pcpu_lstats __percpu *pcpu_lstats; - struct net_device_stats *stats = &dev->stats; - unsigned long bytes = 0; - unsigned long packets = 0; - unsigned long drops = 0; + struct rtnl_link_stats64 *stats = &dev->stats64; + u64 bytes = 0; + u64 packets = 0; + u64 drops = 0; int i; pcpu_lstats = (void __percpu __force *)dev->ml_priv; @@ -108,8 +150,7 @@ static struct net_device_stats *loopback_get_stats(struct net_device *dev) const struct pcpu_lstats *lb_stats; lb_stats = per_cpu_ptr(pcpu_lstats, i); - bytes += lb_stats->bytes; - packets += lb_stats->packets; + lstats_fetch_and_add(&packets, &bytes, lb_stats); drops += lb_stats->drops; } stats->rx_packets = packets; @@ -158,7 +199,7 @@ static void loopback_dev_free(struct net_device *dev) static const struct net_device_ops loopback_ops = { .ndo_init = loopback_dev_init, .ndo_start_xmit= loopback_xmit, - .ndo_get_stats = loopback_get_stats, + .ndo_get_stats64 = loopback_get_stats64, }; /*