Subject: Re: [PATCH net-next 11/12] ipvs: reorder keys in connection structure

From: Hans Schillstrom <[email-masked]>
Date: Thu, 07 Mar 2013 08:49:52 +0100

Hi Julian
On Wed, 2013-03-06 at 23:01 +0200, Julian Anastasov wrote:
> 	Hello,
> 
> On Wed, 6 Mar 2013, Hans Schillstrom wrote:
> 
> > Hi Julian
> > Great job you have done !
> > I'll test it immediate...
> 
> 	Thanks, it would be good to catch the problems
> in early phase...
> 
> > On Wed, 2013-03-06 at 10:42 +0200, Julian Anastasov wrote:
> > > 	__ip_vs_conn_in_get and ip_vs_conn_out_get are
> > > hot places. Optimize them, so that ports are matched first.
> > > By moving net and fwmark below, on 32-bit arch we can fit
> > > caddr in 32-byte cache line and all addresses in 64-byte
> > > cache line.
> > 
> > Earlier I made some rearrangements like the one you have made.
> > My conclusion at that time was that the best gain was to have
> > fwmark and net within the first 64 bytes, and move daddr to the next
> > cache line.
> 
> 	But fwmark is used only for lookups in backup
> server. The net field is checked first only in
> ip_vs_ct_in_get (on scheduling), it can be optimized too.
> Modern CPUs have 64-byte cache line and may be the
> places of these fields do not play much because checking
> the two ports is enough to differentiate most of the
> connections. The addresses play when ports do not
> differ, i.e. mostly for persistent connections. So,
> on 64-byte cache line it would be more difficult to
> see any difference.

I made some tests on weaker machine (i7-3930K) with moderate background
load, there is absolute no measurable difference with daddr in first
cache line or in second line.
So based on that I prefer your solution since it keeps data together.

> > I uesd UDP at ~7Gbit/sec and 256k source address into a x86_64 machine,
> > and a 50/50 mix of fwmarks and port in that tests. 
> > 
> > I guess that you have made similar test, and even take
> > ip_vs_conn_out_get() into your calculations ?
> 
> 	No, I have only virtual boxes for tests...
> 
> > Regards
> > Hans
> > 
> > > 
> > > Signed-off-by: Julian Anastasov <[email-masked]>

Signed-off-by: Hans Schillstrom <[email-masked]>

> > > ---
> > >  include/net/ip_vs.h             |   12 ++++++------
> > >  net/netfilter/ipvs/ip_vs_conn.c |    8 ++++----
> > >  2 files changed, 10 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> > > index 9059360..2bc30e6 100644
> > > --- a/include/net/ip_vs.h
> > > +++ b/include/net/ip_vs.h
> > > @@ -566,20 +566,19 @@ struct ip_vs_conn_param {
> > >   */
> > >  struct ip_vs_conn {
> > >  	struct hlist_node	c_list;         /* hashed list heads */
> > > -#ifdef CONFIG_NET_NS
> > > -	struct net              *net;           /* Name space */
> > > -#endif
> > >  	/* Protocol, addresses and port numbers */
> > > -	u16                     af;             /* address family */
> > >  	__be16                  cport;
> > > -	__be16                  vport;
> > >  	__be16                  dport;
> > > -	__u32                   fwmark;         /* Fire wall mark from skb */
> > > +	__be16                  vport;
> > > +	u16			af;		/* address family */
> > >  	union nf_inet_addr      caddr;          /* client address */
> > >  	union nf_inet_addr      vaddr;          /* virtual address */
> > >  	union nf_inet_addr      daddr;          /* destination address */
> > >  	volatile __u32          flags;          /* status flags */
> > >  	__u16                   protocol;       /* Which protocol (TCP/UDP) */
> > > +#ifdef CONFIG_NET_NS
> > > +	struct net              *net;           /* Name space */
> > > +#endif
> > >  
> > >  	/* counter and timer */
> > >  	atomic_t		refcnt;		/* reference count */
> > > @@ -593,6 +592,7 @@ struct ip_vs_conn {
> > >  						 * state transition triggerd
> > >  						 * synchronization
> > >  						 */
> > > +	__u32			fwmark;		/* Fire wall mark from skb */
> > >  	unsigned long		sync_endtime;	/* jiffies + sent_retries */
> > >  
> > >  	/* Control members */
> > > diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
> > > index b0cd2be..a4d8ec5 100644
> > > --- a/net/netfilter/ipvs/ip_vs_conn.c
> > > +++ b/net/netfilter/ipvs/ip_vs_conn.c
> > > @@ -265,8 +265,8 @@ __ip_vs_conn_in_get(const struct ip_vs_conn_param *p)
> > >  	rcu_read_lock();
> > >  
> > >  	hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
> > > -		if (cp->af == p->af &&
> > > -		    p->cport == cp->cport && p->vport == cp->vport &&
> > > +		if (p->cport == cp->cport && p->vport == cp->vport &&
> > > +		    cp->af == p->af &&
> > >  		    ip_vs_addr_equal(p->af, p->caddr, &cp->caddr) &&
> > >  		    ip_vs_addr_equal(p->af, p->vaddr, &cp->vaddr) &&
> > >  		    ((!p->cport) ^ (!(cp->flags & IP_VS_CONN_F_NO_CPORT))) &&
> > > @@ -404,8 +404,8 @@ struct ip_vs_conn *ip_vs_conn_out_get(const struct ip_vs_conn_param *p)
> > >  	rcu_read_lock();
> > >  
> > >  	hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
> > > -		if (cp->af == p->af &&
> > > -		    p->vport == cp->cport && p->cport == cp->dport &&
> > > +		if (p->vport == cp->cport && p->cport == cp->dport &&
> > > +		    cp->af == p->af &&
> > >  		    ip_vs_addr_equal(p->af, p->vaddr, &cp->caddr) &&
> > >  		    ip_vs_addr_equal(p->af, p->caddr, &cp->daddr) &&
> > >  		    p->protocol == cp->protocol &&
> 
> Regards
> 
> --
> Julian Anastasov <[email-masked]>