On Sun, Jul 09, 2023 at 08:45:19PM +0300, Julian Anastasov wrote:
>
> Hello,
>
>On Fri, 7 Jul 2023, Dust Li wrote:
>
>> From: Jiejian Wu <jiejian@xxxxxxxxxxxxxxxxx>
>>
>> Current ipvs uses one global mutex "__ip_vs_mutex" to keep the global
>> "ip_vs_svc_table" and "ip_vs_svc_fwm_table" safe. But when there are
>> tens of thousands of services from different netns in the table, it
>> takes a long time to look up the table, for example, using "ipvsadm
>> -ln" from different netns simultaneously.
>>
>> We make "ip_vs_svc_table" and "ip_vs_svc_fwm_table" per netns, and we
>> add "service_mutex" per netns to keep these two tables safe instead of
>> the global "__ip_vs_mutex" in current version. To this end, looking up
>> services from different netns simultaneously will not get stuck,
>> shortening the time consumption in large-scale deployment. Evaluation
>> methods and results are provided below.
>>
>> init.sh: #!/bin/bash
>> for((i=1;i<=4;i++));do
>> ip netns add ns$i
>> ip netns exec ns$i ip link set dev lo up
>> ip netns exec ns$i sh add-services.sh
>> done
>>
>> add-services.sh: #!/bin/bash
>> for((i=0;i<30000;i++)); do
>> ipvsadm -A -t 10.10.10.10:$((80+$i)) -s rr
>> done
>>
>> runtest.sh: #!/bin/bash
>> for((i=1;i<4;i++));do
>> ip netns exec ns$i ipvsadm -ln > /dev/null &
>> done
>> ip netns exec ns4 ipvsadm -ln > /dev/null
>>
>> Run "sh init.sh" to initiate the network environment. Then run "time
>> ./runtest.sh" to evaluate the time consumption. Our testbed is a 4-core
>> Intel Xeon ECS. The result of the original version is around 8 seconds,
>> while the result of the modified version is only 0.8 seconds.
>>
>> Signed-off-by: Jiejian Wu <jiejian@xxxxxxxxxxxxxxxxx>
>> Co-developed-by: Dust Li <dust.li@xxxxxxxxxxxxxxxxx>
>> Signed-off-by: Dust Li <dust.li@xxxxxxxxxxxxxxxxx>
>> ---
>> include/net/ip_vs.h | 12 ++++
>> net/netfilter/ipvs/ip_vs_ctl.c | 109 +++++++++++++++------------------
>> 2 files changed, 62 insertions(+), 59 deletions(-)
>>
>> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
>> index ff406ef4fd4aa..83ab2db4a994b 100644
>> --- a/include/net/ip_vs.h
>> +++ b/include/net/ip_vs.h
>> @@ -33,6 +33,12 @@
>>
>> #define IP_VS_HDR_INVERSE 1
>> #define IP_VS_HDR_ICMP 2
>> +/*
>> + * Hash table: for virtual service lookups
>> + */
>> +#define IP_VS_SVC_TAB_BITS 8
>> +#define IP_VS_SVC_TAB_SIZE (1 << IP_VS_SVC_TAB_BITS)
>> +#define IP_VS_SVC_TAB_MASK (IP_VS_SVC_TAB_SIZE - 1)
>>
>> /* Generic access of ipvs struct */
>> static inline struct netns_ipvs *net_ipvs(struct net* net)
>> @@ -1041,6 +1047,12 @@ struct netns_ipvs {
>> */
>> unsigned int mixed_address_family_dests;
>> unsigned int hooks_afmask; /* &1=AF_INET, &2=AF_INET6 */
>> +
>> + struct mutex service_mutex;
>> + /* the service table hashed by <protocol, addr, port> */
>> + struct hlist_head ip_vs_svc_table[IP_VS_SVC_TAB_SIZE];
>> + /* the service table hashed by fwmark */
>> + struct hlist_head ip_vs_svc_fwm_table[IP_VS_SVC_TAB_SIZE];
>
> Can we use svc_table and svc_fwm_table for the table names?
>
Sure, will do.
>> };
>>
>> #define DEFAULT_SYNC_THRESHOLD 3
>> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
>> index 62606fb44d027..c8b30f9ec5106 100644
>> --- a/net/netfilter/ipvs/ip_vs_ctl.c
>> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
>
>> @@ -414,7 +404,7 @@ __ip_vs_service_find(struct netns_ipvs *ipvs, int af, __u16 protocol,
>> /* Check for "full" addressed entries */
>> hash = ip_vs_svc_hashkey(ipvs, af, protocol, vaddr, vport);
>>
>> - hlist_for_each_entry_rcu(svc, &ip_vs_svc_table[hash], s_list) {
>> + hlist_for_each_entry_rcu(svc, &ipvs->ip_vs_svc_table[hash], s_list) {
>> if ((svc->af == af)
>> && ip_vs_addr_equal(af, &svc->addr, vaddr)
>> && (svc->port == vport)
>> @@ -441,7 +431,7 @@ __ip_vs_svc_fwm_find(struct netns_ipvs *ipvs, int af, __u32 fwmark)
>> /* Check for fwmark addressed entries */
>> hash = ip_vs_svc_fwm_hashkey(ipvs, fwmark);
>>
>> - hlist_for_each_entry_rcu(svc, &ip_vs_svc_fwm_table[hash], f_list) {
>> + hlist_for_each_entry_rcu(svc, &ipvs->ip_vs_svc_fwm_table[hash], f_list) {
>> if (svc->fwmark == fwmark && svc->af == af
>> && (svc->ipvs == ipvs)) {
>
> __ip_vs_service_find and __ip_vs_svc_fwm_find: match
>by svc->ipvs is not needed anymore. There are other svc->ipvs == ipvs
>checks in this file.
>
Yes, will remove the check in the next version.
>> @@ -1732,12 +1722,12 @@ void ip_vs_service_nets_cleanup(struct list_head *net_list)
>> struct net *net;
>>
>> /* Check for "full" addressed entries */
>> - mutex_lock(&__ip_vs_mutex);
>> list_for_each_entry(net, net_list, exit_list) {
>> ipvs = net_ipvs(net);
>> + mutex_lock(&ipvs->service_mutex);
>> ip_vs_flush(ipvs, true);
>> + mutex_unlock(&ipvs->service_mutex);
>> }
>> - mutex_unlock(&__ip_vs_mutex);
>
> This reverts speedups from commit 5d5a0815f854 but with some
Yes :)
>reordering we probably can remove the mutex completely as part from
>further optimizations.
>
Agree. It is not a frequently called routine, so we kept it here.
>> }
>>
>> /* Put all references for device (dst_cache) */
>> @@ -1775,9 +1765,9 @@ static int ip_vs_dst_event(struct notifier_block *this, unsigned long event,
>> if (event != NETDEV_DOWN || !ipvs)
>> return NOTIFY_DONE;
>> IP_VS_DBG(3, "%s() dev=%s\n", __func__, dev->name);
>> - mutex_lock(&__ip_vs_mutex);
>> + mutex_lock(&ipvs->service_mutex);
>
> Looks like with global notifier we have a problem where
>ip_vs_dst_event() can not know if net->ipvs is not in process
>of freeing from another CPU. The global __ip_vs_mutex helped
>to avoid the problem, if we see svc then svc->ipvs is valid.
>But now even the ipvs->dest_trash_lock access looks under risk.
>Probably, we should switch to register_netdevice_notifier_net,
>so that ip_vs_dst_event() can safely work with the ipvs struct.
>At first look, unregister_netdevice_notifier_net() should be
>called in ip_vs_control_net_cleanup() just after the
>ip_vs_trash_cleanup() call. A drawback is that when we unregister
>from netns exit context __unregister_netdevice_notifier_net()
>still calls call_netdevice_unregister_net_notifiers, something
>that we do not want. May be we can silence these events with
>some new wrapper/parameter.
>
>> @@ -2303,9 +2293,9 @@ static struct ip_vs_service *ip_vs_info_array(struct seq_file *seq, loff_t pos)
>>
>> /* look in hash by protocol */
>> for (idx = 0; idx < IP_VS_SVC_TAB_SIZE; idx++) {
>> - hlist_for_each_entry_rcu(svc, &ip_vs_svc_table[idx], s_list) {
>> + hlist_for_each_entry_rcu(svc, &ipvs->ip_vs_svc_table[idx], s_list) {
>> if ((svc->ipvs == ipvs) && pos-- == 0) {
>> - iter->table = ip_vs_svc_table;
>> + iter->table = ipvs->ip_vs_svc_table;
>
> We can change iter->table to int table_id, 0 (ip_vs_svc_table)
>and 1 (ip_vs_svc_fwm_table), for all these ip_vs_info_* funcs.
Sorry, I don't get this. Why do we need to change this ?
>
>> iter->bucket = idx;
>> return svc;
>> }
>> @@ -2314,10 +2304,10 @@ static struct ip_vs_service *ip_vs_info_array(struct seq_file *seq, loff_t pos)
>>
>> /* keep looking in fwmark */
>> for (idx = 0; idx < IP_VS_SVC_TAB_SIZE; idx++) {
>> - hlist_for_each_entry_rcu(svc, &ip_vs_svc_fwm_table[idx],
>> + hlist_for_each_entry_rcu(svc, &ipvs->ip_vs_svc_fwm_table[idx],
>> f_list) {
>> if ((svc->ipvs == ipvs) && pos-- == 0) {
>> - iter->table = ip_vs_svc_fwm_table;
>> + iter->table = ipvs->ip_vs_svc_fwm_table;
>> iter->bucket = idx;
>> return svc;
>> }
>
>> @@ -3058,7 +3050,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>> return ret;
>> }
>>
>> - mutex_lock(&__ip_vs_mutex);
>> + mutex_lock(&ipvs->service_mutex);
>> switch (cmd) {
>> case IP_VS_SO_GET_VERSION:
>> {
>> @@ -3157,7 +3149,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>> }
>>
>> out:
>> - mutex_unlock(&__ip_vs_mutex);
>> + mutex_unlock(&ipvs->service_mutex);
>> return ret;
>> }
>>
>> @@ -3392,9 +3384,9 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb,
>> struct net *net = sock_net(skb->sk);
>> struct netns_ipvs *ipvs = net_ipvs(net);
>>
>> - mutex_lock(&__ip_vs_mutex);
>> + mutex_lock(&ipvs->service_mutex);
>
> While do_ip_vs_get_ctl is a reader that can block we
>can not use RCU but in ip_vs_genl_dump_services() we can replace
>the __ip_vs_mutex with rcu_read_lock because we just fill the skb.
>
I think we can replace mutex in ip_vs_genl_dump_services() by RCU.
Do you prefer replacing it in this patch or later ?
>> for (i = 0; i < IP_VS_SVC_TAB_SIZE; i++) {
>> - hlist_for_each_entry(svc, &ip_vs_svc_table[i], s_list) {
>> + hlist_for_each_entry(svc, &ipvs->ip_vs_svc_table[i], s_list) {
>> if (++idx <= start || (svc->ipvs != ipvs))
>> continue;
>> if (ip_vs_genl_dump_service(skb, svc, cb) < 0) {
>> @@ -3405,7 +3397,7 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb,
>> }
>>
>> for (i = 0; i < IP_VS_SVC_TAB_SIZE; i++) {
>> - hlist_for_each_entry(svc, &ip_vs_svc_fwm_table[i], f_list) {
>> + hlist_for_each_entry(svc, &ipvs->ip_vs_svc_fwm_table[i], f_list) {
>> if (++idx <= start || (svc->ipvs != ipvs))
>> continue;
>> if (ip_vs_genl_dump_service(skb, svc, cb) < 0) {
>> @@ -3416,7 +3408,7 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb,
>> }
>>
>> nla_put_failure:
>> - mutex_unlock(&__ip_vs_mutex);
>> + mutex_unlock(&ipvs->service_mutex);
>> cb->args[0] = idx;
>>
>> return skb->len;
>> @@ -3605,7 +3597,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb,
>> struct net *net = sock_net(skb->sk);
>> struct netns_ipvs *ipvs = net_ipvs(net);
>>
>> - mutex_lock(&__ip_vs_mutex);
>> + mutex_lock(&ipvs->service_mutex);
>
> In ip_vs_genl_dump_dests() we can use RCU too but there
>will be probably double rcu_read_lock in ip_vs_genl_parse_service(),
>so rcu_read_lock can be moved into the top caller.
Yes.
>
>>
>> /* Try to find the service for which to dump destinations */
>> if (nlmsg_parse_deprecated(cb->nlh, GENL_HDRLEN, attrs, IPVS_CMD_ATTR_MAX, ip_vs_cmd_policy, cb->extack))
>> @@ -3630,7 +3622,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb,
>> cb->args[0] = idx;
>>
>> out_err:
>> - mutex_unlock(&__ip_vs_mutex);
>> + mutex_unlock(&ipvs->service_mutex);
>>
>> return skb->len;
>> }
>
>> @@ -4058,7 +4050,7 @@ static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info)
>> if (!msg)
>> return -ENOMEM;
>>
>> - mutex_lock(&__ip_vs_mutex);
>> + mutex_lock(&ipvs->service_mutex);
>
> ip_vs_genl_get_cmd is another place that we can use RCU.
>
OK
>>
>> reply = genlmsg_put_reply(msg, info, &ip_vs_genl_family, 0, reply_cmd);
>> if (reply == NULL)
>> @@ -4126,7 +4118,7 @@ static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info)
>> out_err:
>> nlmsg_free(msg);
>> out:
>> - mutex_unlock(&__ip_vs_mutex);
>> + mutex_unlock(&ipvs->service_mutex);
>>
>> return ret;
>> }
>
> Note that ip_vs_est.c uses __ip_vs_mutex too, it should be
>changed to service_mutex. Do not keep __ip_vs_mutex anymore.
OK, will fix in the next version.
>
> Also, there is more work if we want independent
>namespaces and to give power to users:
>
>- account memory: GFP_KERNEL -> GFP_KERNEL_ACCOUNT
>
>- the connections table is still global but it should be possible
>to make all tables per-net and to grow on load from NULL to max bits
>
>- convert GENL_ADMIN_PERM -> GENL_UNS_ADMIN_PERM and make
>sysctls visible to other namespaces
>
> If the plan is to have multiple netns loaded with many
>conns may be I can follow your patch with more optimization
>patches.
Yes, we do missed those details. I think moving those into different
netns is good, besides we already have netns supported. So why not do
it more completely ?
If it is convenient for you to do more optimizations, we would greatly
appreciate it !
Best regards,
Dust
>
>Regards
>
>--
>Julian Anastasov <ja@xxxxxx>
