Re: [PATCH net-next v4] net: ipvs: add sysctl_run_estimation to support disable estimation

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On Sat, Aug 21, 2021 at 11:41:50AM +0300, Julian Anastasov wrote:
> 
> 	Hello,
> 
> On Fri, 20 Aug 2021, Dust Li wrote:
> 
> > estimation_timer will iterate the est_list to do estimation
> > for each ipvs stats. When there are lots of services, the
> > list can be very large.
> > We found that estimation_timer() run for more then 200ms on a
> > machine with 104 CPU and 50K services.
> > 
> > yunhong-cgl jiang report the same phenomenon before:
> > https://www.spinics.net/lists/lvs-devel/msg05426.html
> > 
> > In some cases(for example a large K8S cluster with many ipvs services),
> > ipvs estimation may not be needed. So adding a sysctl blob to allow
> > users to disable this completely.
> > 
> > Default is: 1 (enable)
> > 
> > Cc: yunhong-cgl jiang <xintian1976@xxxxxxxxx>
> > Signed-off-by: Dust Li <dust.li@xxxxxxxxxxxxxxxxx>
> 
> 	Looks good to me, thanks!
> 
> Acked-by: Julian Anastasov <ja@xxxxxx>

Likwewise, thanks. And sorry for the delay.

Acked-by: Simon Horman <horms@xxxxxxxxxxxx>

Pablo, could you consider picking this up?

> > ---
> > v2: Use common sysctl facilities
> > v3: Fix sysctl_run_estimation() redefine when CONFIG_SYSCTL not enabled
> > v4: Some typo and minor fixes
> > 
> >  Documentation/networking/ipvs-sysctl.rst | 11 +++++++++++
> >  include/net/ip_vs.h                      | 11 +++++++++++
> >  net/netfilter/ipvs/ip_vs_ctl.c           |  8 ++++++++
> >  net/netfilter/ipvs/ip_vs_est.c           |  5 +++++
> >  4 files changed, 35 insertions(+)
> > 
> > diff --git a/Documentation/networking/ipvs-sysctl.rst b/Documentation/networking/ipvs-sysctl.rst
> > index 2afccc63856e..95ef56d62077 100644
> > --- a/Documentation/networking/ipvs-sysctl.rst
> > +++ b/Documentation/networking/ipvs-sysctl.rst
> > @@ -300,3 +300,14 @@ sync_version - INTEGER
> >  
> >  	Kernels with this sync_version entry are able to receive messages
> >  	of both version 1 and version 2 of the synchronisation protocol.
> > +
> > +run_estimation - BOOLEAN
> > +	0 - disabled
> > +	not 0 - enabled (default)
> > +
> > +	If disabled, the estimation will be stop, and you can't see
> > +	any update on speed estimation data.
> > +
> > +	You can always re-enable estimation by setting this value to 1.
> > +	But be careful, the first estimation after re-enable is not
> > +	accurate.
> > diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> > index 7cb5a1aace40..ff1804a0c469 100644
> > --- a/include/net/ip_vs.h
> > +++ b/include/net/ip_vs.h
> > @@ -931,6 +931,7 @@ struct netns_ipvs {
> >  	int			sysctl_conn_reuse_mode;
> >  	int			sysctl_schedule_icmp;
> >  	int			sysctl_ignore_tunneled;
> > +	int			sysctl_run_estimation;
> >  
> >  	/* ip_vs_lblc */
> >  	int			sysctl_lblc_expiration;
> > @@ -1071,6 +1072,11 @@ static inline int sysctl_cache_bypass(struct netns_ipvs *ipvs)
> >  	return ipvs->sysctl_cache_bypass;
> >  }
> >  
> > +static inline int sysctl_run_estimation(struct netns_ipvs *ipvs)
> > +{
> > +	return ipvs->sysctl_run_estimation;
> > +}
> > +
> >  #else
> >  
> >  static inline int sysctl_sync_threshold(struct netns_ipvs *ipvs)
> > @@ -1163,6 +1169,11 @@ static inline int sysctl_cache_bypass(struct netns_ipvs *ipvs)
> >  	return 0;
> >  }
> >  
> > +static inline int sysctl_run_estimation(struct netns_ipvs *ipvs)
> > +{
> > +	return 1;
> > +}
> > +
> >  #endif
> >  
> >  /* IPVS core functions
> > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> > index c25097092a06..cbea5a68afb5 100644
> > --- a/net/netfilter/ipvs/ip_vs_ctl.c
> > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> > @@ -2017,6 +2017,12 @@ static struct ctl_table vs_vars[] = {
> >  		.mode		= 0644,
> >  		.proc_handler	= proc_dointvec,
> >  	},
> > +	{
> > +		.procname	= "run_estimation",
> > +		.maxlen		= sizeof(int),
> > +		.mode		= 0644,
> > +		.proc_handler	= proc_dointvec,
> > +	},
> >  #ifdef CONFIG_IP_VS_DEBUG
> >  	{
> >  		.procname	= "debug_level",
> > @@ -4090,6 +4096,8 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> >  	tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode;
> >  	tbl[idx++].data = &ipvs->sysctl_schedule_icmp;
> >  	tbl[idx++].data = &ipvs->sysctl_ignore_tunneled;
> > +	ipvs->sysctl_run_estimation = 1;
> > +	tbl[idx++].data = &ipvs->sysctl_run_estimation;
> >  
> >  	ipvs->sysctl_hdr = register_net_sysctl(net, "net/ipv4/vs", tbl);
> >  	if (ipvs->sysctl_hdr == NULL) {
> > diff --git a/net/netfilter/ipvs/ip_vs_est.c b/net/netfilter/ipvs/ip_vs_est.c
> > index 05b8112ffb37..9a1a7af6a186 100644
> > --- a/net/netfilter/ipvs/ip_vs_est.c
> > +++ b/net/netfilter/ipvs/ip_vs_est.c
> > @@ -100,6 +100,9 @@ static void estimation_timer(struct timer_list *t)
> >  	u64 rate;
> >  	struct netns_ipvs *ipvs = from_timer(ipvs, t, est_timer);
> >  
> > +	if (!sysctl_run_estimation(ipvs))
> > +		goto skip;
> > +
> >  	spin_lock(&ipvs->est_lock);
> >  	list_for_each_entry(e, &ipvs->est_list, list) {
> >  		s = container_of(e, struct ip_vs_stats, est);
> > @@ -131,6 +134,8 @@ static void estimation_timer(struct timer_list *t)
> >  		spin_unlock(&s->lock);
> >  	}
> >  	spin_unlock(&ipvs->est_lock);
> > +
> > +skip:
> >  	mod_timer(&ipvs->est_timer, jiffies + 2*HZ);
> >  }
> >  
> > -- 
> > 2.19.1.3.ge56e4f7
> > 
> > 
> > 
> 
> Regards
> 
> --
> Julian Anastasov <ja@xxxxxx>
> 



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