Messages in this thread Patch in this message | | | From | Mihai Maruseac <> | Subject | [PATCH] dev: use name hash for dev_seq_ops. | Date | Fri, 7 Oct 2011 18:20:49 +0300 |
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Instead of using the dev->next chain and trying to resync at each call to dev_seq_start, use this hash and store bucket number and bucket offset in seq->private field.
Tests revealed the following results for ifconfig > /dev/null * 1000 interfaces: * 0.114s without patch * 0.020s with patch * 3000 interfaces: * 0.489s without patch * 0.048s with patch * 5000 interfaces: * 1.363s without patch * 0.131s with patch
As one can notice the improvement is of 1 order of magnitude.
Signed-off-by: Mihai Maruseac <mmaruseac@ixiacom.com> --- net/core/dev.c | 73 +++++++++++++++++++++++++++++++++++++++++++------------- 1 files changed, 56 insertions(+), 17 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index bf49a47..2d0f126 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4034,6 +4034,51 @@ static int dev_ifconf(struct net *net, char __user *arg) } #ifdef CONFIG_PROC_FS + +struct dev_iter_state { + struct seq_net_private p; + int bucket; + int offset; +}; + +static inline struct net_device *dev_from_same_bucket(struct seq_file *seq) +{ + struct net_device *dev = NULL; + struct net *net = seq_file_net(seq); + struct dev_iter_state *state = seq->private; + struct hlist_node *p; + struct hlist_head *h; + int count; + + h = &net->dev_name_head[state->bucket]; + count = 0; + hlist_for_each_entry_rcu(dev, p, h, name_hlist) { + if (count++ == state->offset) { + state->offset = 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 = NULL; + + while (state->bucket < NETDEV_HASHENTRIES) { + dev = dev_from_same_bucket(seq); + if (dev) + return dev; + + state->bucket++; + state->offset = 0; + } + + return NULL; +} + /* * This is invoked by the /proc filesystem handler to display a device * in detail. @@ -4041,33 +4086,27 @@ 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; - rcu_read_lock(); if (!*pos) return SEQ_START_TOKEN; - off = 1; - for_each_netdev_rcu(net, dev) - if (off++ == *pos) - return dev; - - 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 = NULL; + + ++*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) @@ -4166,7 +4205,7 @@ 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 = { -- 1.7.4.1
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