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  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 04 May 2012 22:53:27 +0200
From:	Eric Dumazet <>
To:	Tom Herbert <>
Cc:	Deng-Cheng Zhu <>,,
Subject: Re: [PATCH v2] RPS: Sparse connection optimizations - v2

On Fri, 2012-05-04 at 17:47 +0200, Eric Dumazet wrote:
> On Fri, 2012-05-04 at 08:31 -0700, Tom Herbert wrote:
> > > I think the mechanisms of rps_dev_flow_table and cpu_flow (in this
> > > patch) are different: The former works along with rps_sock_flow_table
> > > whose CPU info is based on recvmsg by the application. But for the tests
> > > like what I did, there's no application involved.
> > >
> > While rps_sock_flow_table is currently only managed by recvmsg, it
> > still is the general mechanism that maps flows to CPUs for steering.
> > There should be nothing preventing you from populating and managing
> > entries in other ways.
> It might be done from a netfilter module, activated in FORWARD chain for
> example.

A good indicator of the network load of a cpu would be to gather
&per_cpu(softnet_data, cpu)->input_pkt_queue.qlen in an EWMA.

We could dynamically adjust active cpus in RPS set given the load of the

On low load, cpu handling NIC interrupt could also bypass RPS and avoid
IPI to other cpus for low overhead.

tcpu = map->cpus[((u64) skb->rxhash * map->len) >> 32];


	if (map->curlen) {
		tcpu = map->cpus[((u64) skb->rxhash * map->curlen) >> 32];
		if (cpu_online(tcpu)) 
			return tcpu;
	return -1;

Every second or so (to reduce Out Of Order impact), allow curlen to be
incremented/decremented in [0 .. map->len] if load is

To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists