| Message ID | 20240219104238.3782658-1-leitao@debian.org (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,v3] net: sysfs: Do not create sysfs for non BQL device | expand |
On Mon, Feb 19, 2024 at 02:42:36AM -0800, Breno Leitao wrote: > Creation of sysfs entries is expensive, mainly for workloads that > constantly creates netdev and netns often. > > Do not create BQL sysfs entries for devices that don't need, > basically those that do not have a real queue, i.e, devices that has > NETIF_F_LLTX and IFF_NO_QUEUE, such as `lo` interface. > > This will remove the /sys/class/net/eth0/queues/tx-X/byte_queue_limits/ > directory for these devices. > > In the example below, eth0 has the `byte_queue_limits` directory but not > `lo`. > > # ls /sys/class/net/lo/queues/tx-0/ > traffic_class tx_maxrate tx_timeout xps_cpus xps_rxqs > > # ls /sys/class/net/eth0/queues/tx-0/byte_queue_limits/ > hold_time inflight limit limit_max limit_min > > This also removes the #ifdefs, since we can also use netdev_uses_bql() to > check if the config is enabled. (as suggested by Jakub). > > Suggested-by: Eric Dumazet <edumazet@google.com> > Signed-off-by: Breno Leitao <leitao@debian.org> Thanks Breno, I like that this removes sysfs entries for devices for which they do not act on. Although I understand it is not a complete solution - still not all devices that have these entries use BQL - I think a key value there is to alleviate potential confusion for users. And as such, this is a step in the right direction. I also like that some #ifdefs disappear. Reviewed-by: Simon Horman <horms@kernel.org> ...
On Mon, 19 Feb 2024 02:42:36 -0800 Breno Leitao wrote: > Creation of sysfs entries is expensive, mainly for workloads that > constantly creates netdev and netns often. > > Do not create BQL sysfs entries for devices that don't need, > basically those that do not have a real queue, i.e, devices that has > NETIF_F_LLTX and IFF_NO_QUEUE, such as `lo` interface. FTR, I applied v2, thanks!
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 946caefdd959..e2a01b7b7992 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1459,6 +1459,9 @@ static const struct attribute_group dql_group = { .name = "byte_queue_limits", .attrs = dql_attrs, }; +#else +/* Fake declaration, all the code using it should be dead */ +extern const struct attribute_group dql_group; #endif /* CONFIG_BQL */ #ifdef CONFIG_XPS @@ -1696,6 +1699,15 @@ static const struct kobj_type netdev_queue_ktype = { .get_ownership = netdev_queue_get_ownership, }; +static bool netdev_uses_bql(const struct net_device *dev) +{ + if ((dev->features & NETIF_F_LLTX) || + (dev->priv_flags & IFF_NO_QUEUE)) + return false; + + return IS_ENABLED(CONFIG_BQL); +} + static int netdev_queue_add_kobject(struct net_device *dev, int index) { struct netdev_queue *queue = dev->_tx + index; @@ -1713,11 +1725,11 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index) if (error) goto err; -#ifdef CONFIG_BQL - error = sysfs_create_group(kobj, &dql_group); - if (error) - goto err; -#endif + if (netdev_uses_bql(dev)) { + error = sysfs_create_group(kobj, &dql_group); + if (error) + goto err; + } kobject_uevent(kobj, KOBJ_ADD); return 0; @@ -1738,9 +1750,9 @@ static int tx_queue_change_owner(struct net_device *ndev, int index, if (error) return error; -#ifdef CONFIG_BQL - error = sysfs_group_change_owner(kobj, &dql_group, kuid, kgid); -#endif + if (netdev_uses_bql(ndev)) + error = sysfs_group_change_owner(kobj, &dql_group, kuid, kgid); + return error; } #endif /* CONFIG_SYSFS */ @@ -1772,9 +1784,10 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num) if (!refcount_read(&dev_net(dev)->ns.count)) queue->kobj.uevent_suppress = 1; -#ifdef CONFIG_BQL - sysfs_remove_group(&queue->kobj, &dql_group); -#endif + + if (netdev_uses_bql(dev)) + sysfs_remove_group(&queue->kobj, &dql_group); + kobject_put(&queue->kobj); }
Creation of sysfs entries is expensive, mainly for workloads that constantly creates netdev and netns often. Do not create BQL sysfs entries for devices that don't need, basically those that do not have a real queue, i.e, devices that has NETIF_F_LLTX and IFF_NO_QUEUE, such as `lo` interface. This will remove the /sys/class/net/eth0/queues/tx-X/byte_queue_limits/ directory for these devices. In the example below, eth0 has the `byte_queue_limits` directory but not `lo`. # ls /sys/class/net/lo/queues/tx-0/ traffic_class tx_maxrate tx_timeout xps_cpus xps_rxqs # ls /sys/class/net/eth0/queues/tx-0/byte_queue_limits/ hold_time inflight limit limit_max limit_min This also removes the #ifdefs, since we can also use netdev_uses_bql() to check if the config is enabled. (as suggested by Jakub). Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Breno Leitao <leitao@debian.org> --- Changelog v1: * https://lore.kernel.org/all/20240215112729.1778958-1-leitao@debian.org/ v2: * Removed the ifdefs by adding them inside the netdev_uses_bql(), as suggested by Jakub Kicinski. v3: * Added an extra parenthesis between or (||) clauses as suggested by Stephen Hemminger --- net/core/net-sysfs.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-)