| Message ID | 20250414160754.503321-13-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: Cover more per-CPU storage with local nested BH locking. | expand |
Sebastian Andrzej Siewior <bigeasy@linutronix.de> writes: > ovs_frag_data_storage is a per-CPU variable and relies on disabled BH for its > locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT > this data structure requires explicit locking. > > Move ovs_frag_data_storage into the struct ovs_pcpu_storage which already > provides locking for the structure. > > Cc: Aaron Conole <aconole@redhat.com> > Cc: Eelco Chaudron <echaudro@redhat.com> > Cc: Ilya Maximets <i.maximets@ovn.org> > Cc: dev@openvswitch.org > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- I'm going to reply here, but I need to bisect a bit more (though I suspect the results below are due to 11/18). When I tested with this patch there were lots of "unexplained" latency spikes during processing (note, I'm not doing PREEMPT_RT in my testing, but I guess it would smooth the spikes out at the cost of max performance). With the series: [SUM] 0.00-300.00 sec 3.28 TBytes 96.1 Gbits/sec 9417 sender [SUM] 0.00-300.00 sec 3.28 TBytes 96.1 Gbits/sec receiver Without the series: [SUM] 0.00-300.00 sec 3.26 TBytes 95.5 Gbits/sec 149 sender [SUM] 0.00-300.00 sec 3.26 TBytes 95.5 Gbits/sec receiver And while the 'final' numbers might look acceptable, one thing I'll note is I saw multiple stalls as: [ 5] 57.00-58.00 sec 128 KBytes 903 Kbits/sec 0 4.02 MBytes But without the patch, I didn't see such stalls. My testing: 1. Install openvswitch userspace and ipcalc 2. start userspace. 3. Setup two netns and connect them (I have a more complicated script to set up the flows, and I can send that to you) 4. Use iperf3 to test (-P5 -t 300) As I wrote I suspect the locking in 11 is leading to these stalls, as the data I'm sending shouldn't be hitting the frag path. Do these results seem expected to you? > net/openvswitch/actions.c | 20 ++------------------ > net/openvswitch/datapath.h | 16 ++++++++++++++++ > 2 files changed, 18 insertions(+), 18 deletions(-) > > diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c > index f4996c11aefac..4d20eadd77ceb 100644 > --- a/net/openvswitch/actions.c > +++ b/net/openvswitch/actions.c > @@ -39,22 +39,6 @@ > #include "flow_netlink.h" > #include "openvswitch_trace.h" > > -#define MAX_L2_LEN (VLAN_ETH_HLEN + 3 * MPLS_HLEN) > -struct ovs_frag_data { > - unsigned long dst; > - struct vport *vport; > - struct ovs_skb_cb cb; > - __be16 inner_protocol; > - u16 network_offset; /* valid only for MPLS */ > - u16 vlan_tci; > - __be16 vlan_proto; > - unsigned int l2_len; > - u8 mac_proto; > - u8 l2_data[MAX_L2_LEN]; > -}; > - > -static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage); > - > DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage) = { > .bh_lock = INIT_LOCAL_LOCK(bh_lock), > }; > @@ -771,7 +755,7 @@ static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key, > static int ovs_vport_output(struct net *net, struct sock *sk, > struct sk_buff *skb) > { > - struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage); > + struct ovs_frag_data *data = this_cpu_ptr(&ovs_pcpu_storage.frag_data); > struct vport *vport = data->vport; > > if (skb_cow_head(skb, data->l2_len) < 0) { > @@ -823,7 +807,7 @@ static void prepare_frag(struct vport *vport, struct sk_buff *skb, > unsigned int hlen = skb_network_offset(skb); > struct ovs_frag_data *data; > > - data = this_cpu_ptr(&ovs_frag_data_storage); > + data = this_cpu_ptr(&ovs_pcpu_storage.frag_data); > data->dst = skb->_skb_refdst; > data->vport = vport; > data->cb = *OVS_CB(skb); > diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h > index 4a665c3cfa906..1b5348b0f5594 100644 > --- a/net/openvswitch/datapath.h > +++ b/net/openvswitch/datapath.h > @@ -13,6 +13,7 @@ > #include <linux/skbuff.h> > #include <linux/u64_stats_sync.h> > #include <net/ip_tunnels.h> > +#include <net/mpls.h> > > #include "conntrack.h" > #include "flow.h" > @@ -173,6 +174,20 @@ struct ovs_net { > bool xt_label; > }; > > +#define MAX_L2_LEN (VLAN_ETH_HLEN + 3 * MPLS_HLEN) > +struct ovs_frag_data { > + unsigned long dst; > + struct vport *vport; > + struct ovs_skb_cb cb; > + __be16 inner_protocol; > + u16 network_offset; /* valid only for MPLS */ > + u16 vlan_tci; > + __be16 vlan_proto; > + unsigned int l2_len; > + u8 mac_proto; > + u8 l2_data[MAX_L2_LEN]; > +}; > + > struct deferred_action { > struct sk_buff *skb; > const struct nlattr *actions; > @@ -200,6 +215,7 @@ struct action_flow_keys { > struct ovs_pcpu_storage { > struct action_fifo action_fifos; > struct action_flow_keys flow_keys; > + struct ovs_frag_data frag_data; > int exec_level; > struct task_struct *owner; > local_lock_t bh_lock;
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index f4996c11aefac..4d20eadd77ceb 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -39,22 +39,6 @@ #include "flow_netlink.h" #include "openvswitch_trace.h" -#define MAX_L2_LEN (VLAN_ETH_HLEN + 3 * MPLS_HLEN) -struct ovs_frag_data { - unsigned long dst; - struct vport *vport; - struct ovs_skb_cb cb; - __be16 inner_protocol; - u16 network_offset; /* valid only for MPLS */ - u16 vlan_tci; - __be16 vlan_proto; - unsigned int l2_len; - u8 mac_proto; - u8 l2_data[MAX_L2_LEN]; -}; - -static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage); - DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage) = { .bh_lock = INIT_LOCAL_LOCK(bh_lock), }; @@ -771,7 +755,7 @@ static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key, static int ovs_vport_output(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage); + struct ovs_frag_data *data = this_cpu_ptr(&ovs_pcpu_storage.frag_data); struct vport *vport = data->vport; if (skb_cow_head(skb, data->l2_len) < 0) { @@ -823,7 +807,7 @@ static void prepare_frag(struct vport *vport, struct sk_buff *skb, unsigned int hlen = skb_network_offset(skb); struct ovs_frag_data *data; - data = this_cpu_ptr(&ovs_frag_data_storage); + data = this_cpu_ptr(&ovs_pcpu_storage.frag_data); data->dst = skb->_skb_refdst; data->vport = vport; data->cb = *OVS_CB(skb); diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h index 4a665c3cfa906..1b5348b0f5594 100644 --- a/net/openvswitch/datapath.h +++ b/net/openvswitch/datapath.h @@ -13,6 +13,7 @@ #include <linux/skbuff.h> #include <linux/u64_stats_sync.h> #include <net/ip_tunnels.h> +#include <net/mpls.h> #include "conntrack.h" #include "flow.h" @@ -173,6 +174,20 @@ struct ovs_net { bool xt_label; }; +#define MAX_L2_LEN (VLAN_ETH_HLEN + 3 * MPLS_HLEN) +struct ovs_frag_data { + unsigned long dst; + struct vport *vport; + struct ovs_skb_cb cb; + __be16 inner_protocol; + u16 network_offset; /* valid only for MPLS */ + u16 vlan_tci; + __be16 vlan_proto; + unsigned int l2_len; + u8 mac_proto; + u8 l2_data[MAX_L2_LEN]; +}; + struct deferred_action { struct sk_buff *skb; const struct nlattr *actions; @@ -200,6 +215,7 @@ struct action_flow_keys { struct ovs_pcpu_storage { struct action_fifo action_fifos; struct action_flow_keys flow_keys; + struct ovs_frag_data frag_data; int exec_level; struct task_struct *owner; local_lock_t bh_lock;
ovs_frag_data_storage is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Move ovs_frag_data_storage into the struct ovs_pcpu_storage which already provides locking for the structure. Cc: Aaron Conole <aconole@redhat.com> Cc: Eelco Chaudron <echaudro@redhat.com> Cc: Ilya Maximets <i.maximets@ovn.org> Cc: dev@openvswitch.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- net/openvswitch/actions.c | 20 ++------------------ net/openvswitch/datapath.h | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 18 deletions(-)