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author | Mihai Maruseac <mihai.maruseac@gmail.com> | 2011-10-20 20:45:10 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2011-10-21 02:54:38 -0400 |
commit | f04565ddf52e401880f8ba51de0dff8ba51c99fd (patch) | |
tree | 720ebd86cb3012319023389a54ae7152073d6bdb | |
parent | e09eff7fc1c6f011f7bdb304e10d2ceef08c88ab (diff) | |
download | op-kernel-dev-f04565ddf52e401880f8ba51de0dff8ba51c99fd.zip op-kernel-dev-f04565ddf52e401880f8ba51de0dff8ba51c99fd.tar.gz |
dev: use name hash for dev_seq_ops
Instead of using the dev->next chain and trying to resync at each call to
dev_seq_start, use the name hash, keeping the bucket and the offset in
seq->private field.
Tests revealed the following results for ifconfig > /dev/null
* 1000 interfaces:
* 0.114s without patch
* 0.089s with patch
* 3000 interfaces:
* 0.489s without patch
* 0.110s with patch
* 5000 interfaces:
* 1.363s without patch
* 0.250s with patch
* 128000 interfaces (other setup):
* ~100s without patch
* ~30s with patch
Signed-off-by: Mihai Maruseac <mmaruseac@ixiacom.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | net/core/dev.c | 84 |
1 files changed, 69 insertions, 15 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 40d4395..ad5d702 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4093,6 +4093,60 @@ static int dev_ifconf(struct net *net, char __user *arg) } #ifdef CONFIG_PROC_FS + +#define BUCKET_SPACE (32 - NETDEV_HASHBITS) + +struct dev_iter_state { + struct seq_net_private p; + unsigned int pos; /* bucket << BUCKET_SPACE + offset */ +}; + +#define get_bucket(x) ((x) >> BUCKET_SPACE) +#define get_offset(x) ((x) & ((1 << BUCKET_SPACE) - 1)) +#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o)) + +static inline struct net_device *dev_from_same_bucket(struct seq_file *seq) +{ + struct dev_iter_state *state = seq->private; + struct net *net = seq_file_net(seq); + struct net_device *dev; + struct hlist_node *p; + struct hlist_head *h; + unsigned int count, bucket, offset; + + bucket = get_bucket(state->pos); + offset = get_offset(state->pos); + h = &net->dev_name_head[bucket]; + count = 0; + hlist_for_each_entry_rcu(dev, p, h, name_hlist) { + if (count++ == offset) { + state->pos = set_bucket_offset(bucket, count); + return dev; + } + } + + return NULL; +} + +static inline struct net_device *dev_from_new_bucket(struct seq_file *seq) +{ + struct dev_iter_state *state = seq->private; + struct net_device *dev; + unsigned int bucket; + + bucket = get_bucket(state->pos); + do { + dev = dev_from_same_bucket(seq); + if (dev) + return dev; + + bucket++; + state->pos = set_bucket_offset(bucket, 0); + } while (bucket < NETDEV_HASHENTRIES); + + return NULL; +} + /* * This is invoked by the /proc filesystem handler to display a device * in detail. @@ -4100,33 +4154,33 @@ static int dev_ifconf(struct net *net, char __user *arg) void *dev_seq_start(struct seq_file *seq, loff_t *pos) __acquires(RCU) { - struct net *net = seq_file_net(seq); - loff_t off; - struct net_device *dev; + struct dev_iter_state *state = seq->private; rcu_read_lock(); if (!*pos) return SEQ_START_TOKEN; - off = 1; - for_each_netdev_rcu(net, dev) - if (off++ == *pos) - return dev; + /* check for end of the hash */ + if (state->pos == 0 && *pos > 1) + return NULL; - return NULL; + return dev_from_new_bucket(seq); } void *dev_seq_next(struct seq_file *seq, void *v, loff_t *pos) { - struct net_device *dev = v; + struct net_device *dev; + + ++*pos; if (v == SEQ_START_TOKEN) - dev = first_net_device_rcu(seq_file_net(seq)); - else - dev = next_net_device_rcu(dev); + return dev_from_new_bucket(seq); - ++*pos; - return dev; + dev = dev_from_same_bucket(seq); + if (dev) + return dev; + + return dev_from_new_bucket(seq); } void dev_seq_stop(struct seq_file *seq, void *v) @@ -4225,7 +4279,7 @@ static const struct seq_operations dev_seq_ops = { static int dev_seq_open(struct inode *inode, struct file *file) { return seq_open_net(inode, file, &dev_seq_ops, - sizeof(struct seq_net_private)); + sizeof(struct dev_iter_state)); } static const struct file_operations dev_seq_fops = { |