From: Martin KaFai Lau <kafai@fb•com>
To: Steffen Klassert <steffen.klassert@secunet•com>
Cc: <netdev@vger•kernel.org>,
Hannes Frederic Sowa <hannes@stressinduktion•org>,
<kernel-team@fb•com>
Subject: Re: [RFC PATCH net-next 10/10] ipv6: Create percpu rt6_info
Date: Mon, 13 Apr 2015 13:16:17 -0700 [thread overview]
Message-ID: <20150413201617.GA2211108@devbig242.prn2.facebook.com> (raw)
In-Reply-To: <20150413105944.GE8928@secunet.com>
On Mon, Apr 13, 2015 at 12:59:44PM +0200, Steffen Klassert wrote:
> On Fri, Apr 10, 2015 at 06:59:36PM -0700, Martin KaFai Lau wrote:
>
> > diff --git a/include/uapi/linux/ipv6_route.h b/include/uapi/linux/ipv6_route.h
> > index 2be7bd1..f6598d1 100644
> > --- a/include/uapi/linux/ipv6_route.h
> > +++ b/include/uapi/linux/ipv6_route.h
> > @@ -34,6 +34,7 @@
> > #define RTF_PREF(pref) ((pref) << 27)
> > #define RTF_PREF_MASK 0x18000000
> >
> > +#define RTF_PCPU 0x40000000
>
> This percpu flag is something internal, should IMO not be added
> to the uapi.
Make sense. Where may be the right place for it?
It seems 'uapi/linux/ipv6_route.h' is the one which has all IPv6 flags laid out.
It makes modification easier since it tells us which bit is still available.
How about we add a comment to 'uapi/linux/ipv6_route.h' and move the '#define'
to 'linux/ipv6_route.h'?
>
> > @@ -1978,8 +2100,13 @@ static void ip6_rt_copy_init(struct rt6_info *rt,
> > static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
> > const struct in6_addr *dest)
> > {
> > - struct rt6_info *rt = ip6_dst_alloc(dev_net(ort->dst.dev), ort->dst.dev,
> > - 0, ort->rt6i_table);
> > + struct rt6_info *rt;
> > +
> > + if (ort->rt6i_flags & RTF_PCPU)
> > + ort = (struct rt6_info *)ort->dst.from;
> > +
> > + rt = __ip6_dst_alloc(dev_net(ort->dst.dev), ort->dst.dev,
> > + 0, ort->rt6i_table);
>
> Why don't you allocate the percpu resources for cached routes?
> I think using ip6_dst_alloc() would be better here, cached routes
> could benefit from this too.
Not sure if we want to open up percpu cache opportunity for RTF_CACHE
route after receiving ICMPv6 too-big from remote peers and some of our machines
have a lot of CPU (like 40), so I opt not to do it.
If we do this, we probably need to modify the gc and its related counting also.
> And in particular rt6_release() tries
> to free the percpu resources unconditionally when the route is removed
> from the fib tree. This crashes if the percpu resources are not allocated.
Good catch and will fix in v2.
Thanks,
--Martin
next prev parent reply other threads:[~2015-04-13 20:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-11 1:59 [RFC PATCH net-next 00/10] ipv6: Only create RTF_CACHE route after encountering pmtu exception Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 01/10] ipv6: Remove external dependency on rt6i_dst and rt6i_src Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 02/10] ipv6: Remove external dependency on rt6i_gateway and RTF_ANYCAST Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 03/10] ipv6: Combine rt6_alloc_cow and rt6_alloc_clone Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 04/10] ipv6: Only create RTF_CACHE routes after encountering pmtu exception Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 05/10] ipv6: Allow pmtu update on /128 via gateway route Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 06/10] ipv6: Avoid deleting RTF_CACHE route from ip6_route_del() Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 07/10] ipv6: Extend the route lookups to low priority metrics Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 08/10] ipv6: Do not use inetpeer when creating RTF_CACHE route for /128 via gateway entry Martin KaFai Lau
2015-04-13 11:06 ` Steffen Klassert
2015-04-13 17:51 ` Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 09/10] ipv6: Break up ip6_rt_copy() Martin KaFai Lau
2015-04-11 1:59 ` [RFC PATCH net-next 10/10] ipv6: Create percpu rt6_info Martin KaFai Lau
2015-04-13 10:59 ` Steffen Klassert
2015-04-13 20:16 ` Martin KaFai Lau [this message]
2015-04-13 21:46 ` Hannes Frederic Sowa
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