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![Willem de Bruijn](/assets/img/avatar_default.png)
A cpu executing the network receive path sheds packets when its input queue grows to netdev_max_backlog. A single high rate flow (such as a spoofed source DoS) can exceed a single cpu processing rate and will degrade throughput of other flows hashed onto the same cpu. This patch adds a more fine grained hashtable. If the netdev backlog is above a threshold, IRQ cpus track the ratio of total traffic of each flow (using 4096 buckets, configurable). The ratio is measured by counting the number of packets per flow over the last 256 packets from the source cpu. Any flow that occupies a large fraction of this (set at 50%) will see packet drop while above the threshold. Tested: Setup is a muli-threaded UDP echo server with network rx IRQ on cpu0, kernel receive (RPS) on cpu0 and application threads on cpus 2--7 each handling 20k req/s. Throughput halves when hit with a 400 kpps antagonist storm. With this patch applied, antagonist overload is dropped and the server processes its complete load. The patch is effective when kernel receive processing is the bottleneck. The above RPS scenario is a extreme, but the same is reached with RFS and sufficient kernel processing (iptables, packet socket tap, ..). Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
423 lines
9.6 KiB
C
423 lines
9.6 KiB
C
#include <linux/netdevice.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <net/wext.h>
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#define BUCKET_SPACE (32 - NETDEV_HASHBITS - 1)
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#define get_bucket(x) ((x) >> BUCKET_SPACE)
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#define get_offset(x) ((x) & ((1 << BUCKET_SPACE) - 1))
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#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
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extern struct list_head ptype_all __read_mostly;
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extern struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
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static inline struct net_device *dev_from_same_bucket(struct seq_file *seq, loff_t *pos)
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{
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struct net *net = seq_file_net(seq);
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struct net_device *dev;
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struct hlist_head *h;
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unsigned int count = 0, offset = get_offset(*pos);
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h = &net->dev_name_head[get_bucket(*pos)];
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hlist_for_each_entry_rcu(dev, h, name_hlist) {
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if (++count == offset)
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return dev;
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}
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return NULL;
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}
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static inline struct net_device *dev_from_bucket(struct seq_file *seq, loff_t *pos)
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{
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struct net_device *dev;
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unsigned int bucket;
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do {
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dev = dev_from_same_bucket(seq, pos);
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if (dev)
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return dev;
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bucket = get_bucket(*pos) + 1;
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*pos = set_bucket_offset(bucket, 1);
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} while (bucket < NETDEV_HASHENTRIES);
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return NULL;
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}
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/*
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* This is invoked by the /proc filesystem handler to display a device
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* in detail.
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*/
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static void *dev_seq_start(struct seq_file *seq, loff_t *pos)
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__acquires(RCU)
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{
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rcu_read_lock();
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if (!*pos)
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return SEQ_START_TOKEN;
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if (get_bucket(*pos) >= NETDEV_HASHENTRIES)
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return NULL;
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return dev_from_bucket(seq, pos);
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}
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static void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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++*pos;
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return dev_from_bucket(seq, pos);
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}
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static void dev_seq_stop(struct seq_file *seq, void *v)
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__releases(RCU)
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{
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rcu_read_unlock();
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}
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static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
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{
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struct rtnl_link_stats64 temp;
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const struct rtnl_link_stats64 *stats = dev_get_stats(dev, &temp);
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seq_printf(seq, "%6s: %7llu %7llu %4llu %4llu %4llu %5llu %10llu %9llu "
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"%8llu %7llu %4llu %4llu %4llu %5llu %7llu %10llu\n",
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dev->name, stats->rx_bytes, stats->rx_packets,
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stats->rx_errors,
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stats->rx_dropped + stats->rx_missed_errors,
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stats->rx_fifo_errors,
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stats->rx_length_errors + stats->rx_over_errors +
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stats->rx_crc_errors + stats->rx_frame_errors,
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stats->rx_compressed, stats->multicast,
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stats->tx_bytes, stats->tx_packets,
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stats->tx_errors, stats->tx_dropped,
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stats->tx_fifo_errors, stats->collisions,
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stats->tx_carrier_errors +
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stats->tx_aborted_errors +
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stats->tx_window_errors +
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stats->tx_heartbeat_errors,
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stats->tx_compressed);
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}
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/*
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* Called from the PROCfs module. This now uses the new arbitrary sized
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* /proc/net interface to create /proc/net/dev
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*/
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static int dev_seq_show(struct seq_file *seq, void *v)
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{
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if (v == SEQ_START_TOKEN)
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seq_puts(seq, "Inter-| Receive "
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" | Transmit\n"
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" face |bytes packets errs drop fifo frame "
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"compressed multicast|bytes packets errs "
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"drop fifo colls carrier compressed\n");
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else
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dev_seq_printf_stats(seq, v);
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return 0;
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}
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static struct softnet_data *softnet_get_online(loff_t *pos)
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{
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struct softnet_data *sd = NULL;
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while (*pos < nr_cpu_ids)
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if (cpu_online(*pos)) {
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sd = &per_cpu(softnet_data, *pos);
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break;
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} else
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++*pos;
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return sd;
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}
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static void *softnet_seq_start(struct seq_file *seq, loff_t *pos)
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{
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return softnet_get_online(pos);
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}
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static void *softnet_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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++*pos;
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return softnet_get_online(pos);
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}
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static void softnet_seq_stop(struct seq_file *seq, void *v)
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{
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}
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static int softnet_seq_show(struct seq_file *seq, void *v)
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{
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struct softnet_data *sd = v;
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unsigned int flow_limit_count = 0;
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#ifdef CONFIG_NET_FLOW_LIMIT
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struct sd_flow_limit *fl;
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rcu_read_lock();
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fl = rcu_dereference(sd->flow_limit);
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if (fl)
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flow_limit_count = fl->count;
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rcu_read_unlock();
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#endif
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seq_printf(seq,
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"%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
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sd->processed, sd->dropped, sd->time_squeeze, 0,
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0, 0, 0, 0, /* was fastroute */
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sd->cpu_collision, sd->received_rps, flow_limit_count);
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return 0;
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}
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static const struct seq_operations dev_seq_ops = {
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.start = dev_seq_start,
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.next = dev_seq_next,
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.stop = dev_seq_stop,
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.show = dev_seq_show,
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};
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static int dev_seq_open(struct inode *inode, struct file *file)
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{
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return seq_open_net(inode, file, &dev_seq_ops,
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sizeof(struct seq_net_private));
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}
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static const struct file_operations dev_seq_fops = {
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.owner = THIS_MODULE,
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.open = dev_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release_net,
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};
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static const struct seq_operations softnet_seq_ops = {
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.start = softnet_seq_start,
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.next = softnet_seq_next,
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.stop = softnet_seq_stop,
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.show = softnet_seq_show,
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};
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static int softnet_seq_open(struct inode *inode, struct file *file)
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{
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return seq_open(file, &softnet_seq_ops);
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}
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static const struct file_operations softnet_seq_fops = {
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.owner = THIS_MODULE,
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.open = softnet_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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static void *ptype_get_idx(loff_t pos)
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{
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struct packet_type *pt = NULL;
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loff_t i = 0;
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int t;
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list_for_each_entry_rcu(pt, &ptype_all, list) {
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if (i == pos)
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return pt;
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++i;
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}
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for (t = 0; t < PTYPE_HASH_SIZE; t++) {
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list_for_each_entry_rcu(pt, &ptype_base[t], list) {
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if (i == pos)
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return pt;
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++i;
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}
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}
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return NULL;
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}
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static void *ptype_seq_start(struct seq_file *seq, loff_t *pos)
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__acquires(RCU)
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{
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rcu_read_lock();
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return *pos ? ptype_get_idx(*pos - 1) : SEQ_START_TOKEN;
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}
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static void *ptype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct packet_type *pt;
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struct list_head *nxt;
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int hash;
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++*pos;
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if (v == SEQ_START_TOKEN)
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return ptype_get_idx(0);
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pt = v;
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nxt = pt->list.next;
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if (pt->type == htons(ETH_P_ALL)) {
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if (nxt != &ptype_all)
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goto found;
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hash = 0;
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nxt = ptype_base[0].next;
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} else
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hash = ntohs(pt->type) & PTYPE_HASH_MASK;
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while (nxt == &ptype_base[hash]) {
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if (++hash >= PTYPE_HASH_SIZE)
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return NULL;
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nxt = ptype_base[hash].next;
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}
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found:
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return list_entry(nxt, struct packet_type, list);
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}
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static void ptype_seq_stop(struct seq_file *seq, void *v)
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__releases(RCU)
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{
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rcu_read_unlock();
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}
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static int ptype_seq_show(struct seq_file *seq, void *v)
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{
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struct packet_type *pt = v;
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if (v == SEQ_START_TOKEN)
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seq_puts(seq, "Type Device Function\n");
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else if (pt->dev == NULL || dev_net(pt->dev) == seq_file_net(seq)) {
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if (pt->type == htons(ETH_P_ALL))
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seq_puts(seq, "ALL ");
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else
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seq_printf(seq, "%04x", ntohs(pt->type));
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seq_printf(seq, " %-8s %pf\n",
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pt->dev ? pt->dev->name : "", pt->func);
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}
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return 0;
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}
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static const struct seq_operations ptype_seq_ops = {
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.start = ptype_seq_start,
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.next = ptype_seq_next,
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.stop = ptype_seq_stop,
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.show = ptype_seq_show,
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};
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static int ptype_seq_open(struct inode *inode, struct file *file)
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{
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return seq_open_net(inode, file, &ptype_seq_ops,
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sizeof(struct seq_net_private));
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}
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static const struct file_operations ptype_seq_fops = {
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.owner = THIS_MODULE,
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.open = ptype_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release_net,
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};
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static int __net_init dev_proc_net_init(struct net *net)
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{
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int rc = -ENOMEM;
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if (!proc_create("dev", S_IRUGO, net->proc_net, &dev_seq_fops))
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goto out;
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if (!proc_create("softnet_stat", S_IRUGO, net->proc_net,
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&softnet_seq_fops))
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goto out_dev;
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if (!proc_create("ptype", S_IRUGO, net->proc_net, &ptype_seq_fops))
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goto out_softnet;
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if (wext_proc_init(net))
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goto out_ptype;
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rc = 0;
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out:
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return rc;
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out_ptype:
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remove_proc_entry("ptype", net->proc_net);
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out_softnet:
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remove_proc_entry("softnet_stat", net->proc_net);
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out_dev:
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remove_proc_entry("dev", net->proc_net);
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goto out;
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}
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static void __net_exit dev_proc_net_exit(struct net *net)
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{
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wext_proc_exit(net);
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remove_proc_entry("ptype", net->proc_net);
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remove_proc_entry("softnet_stat", net->proc_net);
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remove_proc_entry("dev", net->proc_net);
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}
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static struct pernet_operations __net_initdata dev_proc_ops = {
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.init = dev_proc_net_init,
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.exit = dev_proc_net_exit,
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};
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static int dev_mc_seq_show(struct seq_file *seq, void *v)
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{
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struct netdev_hw_addr *ha;
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struct net_device *dev = v;
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if (v == SEQ_START_TOKEN)
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return 0;
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netif_addr_lock_bh(dev);
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netdev_for_each_mc_addr(ha, dev) {
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int i;
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seq_printf(seq, "%-4d %-15s %-5d %-5d ", dev->ifindex,
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dev->name, ha->refcount, ha->global_use);
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for (i = 0; i < dev->addr_len; i++)
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seq_printf(seq, "%02x", ha->addr[i]);
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seq_putc(seq, '\n');
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}
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netif_addr_unlock_bh(dev);
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return 0;
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}
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static const struct seq_operations dev_mc_seq_ops = {
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.start = dev_seq_start,
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.next = dev_seq_next,
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.stop = dev_seq_stop,
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.show = dev_mc_seq_show,
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};
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static int dev_mc_seq_open(struct inode *inode, struct file *file)
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{
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return seq_open_net(inode, file, &dev_mc_seq_ops,
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sizeof(struct seq_net_private));
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}
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static const struct file_operations dev_mc_seq_fops = {
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.owner = THIS_MODULE,
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.open = dev_mc_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release_net,
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};
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static int __net_init dev_mc_net_init(struct net *net)
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{
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if (!proc_create("dev_mcast", 0, net->proc_net, &dev_mc_seq_fops))
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return -ENOMEM;
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return 0;
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}
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static void __net_exit dev_mc_net_exit(struct net *net)
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{
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remove_proc_entry("dev_mcast", net->proc_net);
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}
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static struct pernet_operations __net_initdata dev_mc_net_ops = {
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.init = dev_mc_net_init,
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.exit = dev_mc_net_exit,
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};
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int __init dev_proc_init(void)
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{
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int ret = register_pernet_subsys(&dev_proc_ops);
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if (!ret)
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return register_pernet_subsys(&dev_mc_net_ops);
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return ret;
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}
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