lkml.org 
[lkml]   [2011]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] dev: use name hash for dev_seq_ops.
Date
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


\
 
 \ /
  Last update: 2011-10-07 17:23    [W:0.193 / U:0.472 seconds]
©2003-2014 Jasper Spaans. Advertise on this site