| Message ID | 200911130720.19671.opurdila@ixiacom.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Fri, 13 Nov 2009 07:20:19 +0200 Octavian Purdila <opurdila@ixiacom.com> wrote: > On Friday 13 November 2009 07:01:14 you wrote: > > This patch speeds up the network device name allocation for the case > > where a significant number of devices of the same type are created > > consecutively. > > > > Tests performed on a PPC750 @ 800Mhz machine with per device sysctl > > and sysfs entries disabled: > > > > Without the patch With the patch > > > > real 0m 43.43s real 0m 0.49s > > user 0m 0.00s user 0m 0.00s > > sys 0m 43.43s sys 0m 0.48s Since the main overhead here is building the bitmap table used in the name scan. Why not mantain the bitmap table between calls by implementing a rbtree with prefix -> bitmap. The tree would have to be limited and per namespace but then you could handle the general case of adding a device, then its vlans, then another device, ...
On Saturday 14 November 2009 02:04:45 you wrote: > On Fri, 13 Nov 2009 07:20:19 +0200 > > Octavian Purdila <opurdila@ixiacom.com> wrote: > > On Friday 13 November 2009 07:01:14 you wrote: > > > This patch speeds up the network device name allocation for the case > > > where a significant number of devices of the same type are created > > > consecutively. > > > > > > Tests performed on a PPC750 @ 800Mhz machine with per device sysctl > > > and sysfs entries disabled: > > > > > > Without the patch With the patch > > > > > > real 0m 43.43s real 0m 0.49s > > > user 0m 0.00s user 0m 0.00s > > > sys 0m 43.43s sys 0m 0.48s > > Since the main overhead here is building the bitmap table used in the > name scan. Why not mantain the bitmap table between calls by > implementing a rbtree with prefix -> bitmap. > The tree would have to be limited and per namespace but then you > could handle the general case of adding a device, then its vlans, > then another device, ... > I'll do that ! That was my original intent but I thought it would be too much bloat :) But I see your point, even if it is more complex, its more useful. Thanks, tavi -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, 14 Nov 2009 02:14:21 +0200 Octavian Purdila <opurdila@ixiacom.com> wrote: > On Saturday 14 November 2009 02:04:45 you wrote: > > On Fri, 13 Nov 2009 07:20:19 +0200 > > > > Octavian Purdila <opurdila@ixiacom.com> wrote: > > > On Friday 13 November 2009 07:01:14 you wrote: > > > > This patch speeds up the network device name allocation for the case > > > > where a significant number of devices of the same type are created > > > > consecutively. > > > > > > > > Tests performed on a PPC750 @ 800Mhz machine with per device sysctl > > > > and sysfs entries disabled: > > > > > > > > Without the patch With the patch > > > > > > > > real 0m 43.43s real 0m 0.49s > > > > user 0m 0.00s user 0m 0.00s > > > > sys 0m 43.43s sys 0m 0.48s > > > > Since the main overhead here is building the bitmap table used in the > > name scan. Why not mantain the bitmap table between calls by > > implementing a rbtree with prefix -> bitmap. > > The tree would have to be limited and per namespace but then you > > could handle the general case of adding a device, then its vlans, > > then another device, ... > > > > I'll do that ! > > That was my original intent but I thought it would be too much bloat :) But I > see your point, even if it is more complex, its more useful. There might even be a VM notifier hook that could be used to drop the whole tree if any memory pressure was felt.
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 0addd45..39c65a2 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -56,6 +56,9 @@ struct net { struct list_head dev_base_head; struct hlist_head *dev_name_head; struct hlist_head *dev_index_head; + /* fast consecutive name allocation (e.g. eth0, eth1, ...) */ + char fcna_name[IFNAMSIZ]; + int fcna_no; /* core fib_rules */ struct list_head rules_ops; diff --git a/net/core/dev.c b/net/core/dev.c index ad8e320..008e3c7 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -226,8 +226,12 @@ static int list_netdevice(struct net_device *dev) */ static void unlist_netdevice(struct net_device *dev) { + struct net *net = dev_net(dev); + ASSERT_RTNL(); + net->fcna_no = -1; + /* Unlink dev from the device chain */ write_lock_bh(&dev_base_lock); list_del_rcu(&dev->dev_list); @@ -872,6 +876,16 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) if (p[1] != 'd' || strchr(p + 2, '%')) return -EINVAL; + /* avoid fast allocation for strange templates like "fan%dcy" */ + if (net->fcna_no >= 0 && p[2] == 0 && + net->fcna_name[p - name] == 0 && + memcmp(name, net->fcna_name, p - name) == 0) { + snprintf(buf, IFNAMSIZ, name, ++net->fcna_no); + if (!__dev_get_by_name(net, buf)) + return net->fcna_no; + net->fcna_no = -1; + } + /* Use one page as a bit array of possible slots */ inuse = (unsigned long *) get_zeroed_page(GFP_ATOMIC); if (!inuse) @@ -894,8 +908,15 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) } snprintf(buf, IFNAMSIZ, name, i); - if (!__dev_get_by_name(net, buf)) + if (!__dev_get_by_name(net, buf)) { + if (p[2] == 0) { + memcpy(net->fcna_name, name, p - name); + net->fcna_name[p - name] = 0; + net->fcna_no = i; + } else + net->fcna_no = -1; return i; + } /* It is possible to run out of possible slots * when the name is long and there isn't enough space left