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net: factorize sync-rcu call in unregister_netdevice_many 

Add dev_close_many and dev_deactivate_many to factorize another
sync-rcu operation on the netdevice unregister path.

$ modprobe dummy numdummies=10000
$ ip link set dev dummy* up
$ time rmmod dummy

Without the patch           With the patch

real    0m 24.63s           real    0m 5.15s
user    0m 0.00s            user    0m 0.00s
sys     0m 6.05s            sys     0m 5.14s

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Octavian Purdila 2010-12-13 12:44:07 +00:00 committed by David S. Miller
parent c6c8fea297
commit 443457242b
3 changed files with 102 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/sch_generic.h
View File

@ -321,6 +321,7 @@ extern void dev_init_scheduler(struct net_device *dev);
extern void dev_shutdown(struct net_device *dev);
extern void dev_activate(struct net_device *dev);
extern void dev_deactivate(struct net_device *dev);
extern void dev_deactivate_many(struct list_head *head);
extern struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
struct Qdisc *qdisc);
extern void qdisc_reset(struct Qdisc *qdisc);

124
net/core/dev.c
View File

@ -1222,52 +1222,90 @@ int dev_open(struct net_device *dev)
}
EXPORT_SYMBOL(dev_open);
static int __dev_close(struct net_device *dev)
static int __dev_close_many(struct list_head *head)
{
const struct net_device_ops *ops = dev->netdev_ops;
struct net_device *dev;
ASSERT_RTNL();
might_sleep();
/*
* Tell people we are going down, so that they can
* prepare to death, when device is still operating.
*/
call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
list_for_each_entry(dev, head, unreg_list) {
/*
* Tell people we are going down, so that they can
* prepare to death, when device is still operating.
*/
call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
clear_bit(__LINK_STATE_START, &dev->state);
clear_bit(__LINK_STATE_START, &dev->state);
/* Synchronize to scheduled poll. We cannot touch poll list,
* it can be even on different cpu. So just clear netif_running().
*
* dev->stop() will invoke napi_disable() on all of it's
* napi_struct instances on this device.
*/
smp_mb__after_clear_bit(); /* Commit netif_running(). */
/* Synchronize to scheduled poll. We cannot touch poll list, it
* can be even on different cpu. So just clear netif_running().
*
* dev->stop() will invoke napi_disable() on all of it's
* napi_struct instances on this device.
*/
smp_mb__after_clear_bit(); /* Commit netif_running(). */
}
dev_deactivate(dev);
dev_deactivate_many(head);
list_for_each_entry(dev, head, unreg_list) {
const struct net_device_ops *ops = dev->netdev_ops;
/*
* Call the device specific close. This cannot fail.
* Only if device is UP
*
* We allow it to be called even after a DETACH hot-plug
* event.
*/
if (ops->ndo_stop)
ops->ndo_stop(dev);
/*
* Device is now down.
*/
dev->flags &= ~IFF_UP;
/*
* Shutdown NET_DMA
*/
net_dmaengine_put();
}
return 0;
}
static int __dev_close(struct net_device *dev)
{
LIST_HEAD(single);
list_add(&dev->unreg_list, &single);
return __dev_close_many(&single);
}
int dev_close_many(struct list_head *head)
{
struct net_device *dev, *tmp;
LIST_HEAD(tmp_list);
list_for_each_entry_safe(dev, tmp, head, unreg_list)
if (!(dev->flags & IFF_UP))
list_move(&dev->unreg_list, &tmp_list);
__dev_close_many(head);
/*
* Call the device specific close. This cannot fail.
* Only if device is UP
*
* We allow it to be called even after a DETACH hot-plug
* event.
* Tell people we are down
*/
if (ops->ndo_stop)
ops->ndo_stop(dev);
/*
* Device is now down.
*/
dev->flags &= ~IFF_UP;
/*
* Shutdown NET_DMA
*/
net_dmaengine_put();
list_for_each_entry(dev, head, unreg_list) {
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
}
/* rollback_registered_many needs the complete original list */
list_splice(&tmp_list, head);
return 0;
}
@ -1282,16 +1320,10 @@ static int __dev_close(struct net_device *dev)
*/
int dev_close(struct net_device *dev)
{
if (!(dev->flags & IFF_UP))
return 0;
LIST_HEAD(single);
__dev_close(dev);
/*
* Tell people we are down
*/
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
list_add(&dev->unreg_list, &single);
dev_close_many(&single);
return 0;
}
@ -4963,10 +4995,12 @@ static void rollback_registered_many(struct list_head *head)
}
BUG_ON(dev->reg_state != NETREG_REGISTERED);
}
/* If device is running, close it first. */
dev_close(dev);
/* If device is running, close it first. */
dev_close_many(head);
list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
unlist_netdevice(dev);

29
net/sched/sch_generic.c
View File

@ -810,20 +810,35 @@ static bool some_qdisc_is_busy(struct net_device *dev)
return false;
}
void dev_deactivate(struct net_device *dev)
void dev_deactivate_many(struct list_head *head)
{
netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
if (dev_ingress_queue(dev))
dev_deactivate_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
struct net_device *dev;
dev_watchdog_down(dev);
list_for_each_entry(dev, head, unreg_list) {
netdev_for_each_tx_queue(dev, dev_deactivate_queue,
&noop_qdisc);
if (dev_ingress_queue(dev))
dev_deactivate_queue(dev, dev_ingress_queue(dev),
&noop_qdisc);
dev_watchdog_down(dev);
}
/* Wait for outstanding qdisc-less dev_queue_xmit calls. */
synchronize_rcu();
/* Wait for outstanding qdisc_run calls. */
while (some_qdisc_is_busy(dev))
yield();
list_for_each_entry(dev, head, unreg_list)
while (some_qdisc_is_busy(dev))
yield();
}
void dev_deactivate(struct net_device *dev)
{
LIST_HEAD(single);
list_add(&dev->unreg_list, &single);
dev_deactivate_many(&single);
}
static void dev_init_scheduler_queue(struct net_device *dev,