netdev - Re: [PATCH 1/5] soreuseport: infrastructure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1358266444.8744.5892.camel@edumazet-glaptop>
Date:	Tue, 15 Jan 2013 08:14:04 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org,
	davem@...emloft.net, netdev@...kandruth.co.uk
Subject: Re: [PATCH 1/5] soreuseport: infrastructure

On Tue, 2013-01-15 at 07:53 -0800, Stephen Hemminger wrote:
> On Mon, 14 Jan 2013 12:00:18 -0800 (PST)
> Tom Herbert <therbert@...gle.com> wrote:
> 
> > +/* Pseudo random number generator from numerical recipes. */
> > +static inline u32 next_pseudo_random32(u32 seed)
> > +{
> > +	return seed * 1664525 + 1013904223;
> > +}
> > +
> 
> Don't reimplement a pseudo random number generator, there already
> exists net_random() 

net_random() is way more expensive and not needed in this context.

If you have 32 listeners bound on the same port, we can call this 32
times per SYN message.

Initial seed is random enough (phash = inet_ehashfn(net, daddr,
hnum,saddr,sport)

Anyway, the full idea of distributing SYN using a random generator is
not the best one for a multi queue NIC, and/or if RPS/RFS is used.

Ideally, we should chose a target given by the current CPU number, in
case SYN messages are spread on all cpus or a set of cpus.

(same idea than PACKET_FANOUT_CPU in net/packet/af_packet.c)




--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html