netdev - Re: [RFC v2: Patch 1/3] net: hand off skb list to other cpu to submit to upper layer

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 for Android: free password hash cracker in your pocket

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

Date:	Fri, 13 Mar 2009 11:51:37 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	therbert@...gle.com
Cc:	yanmin_zhang@...ux.intel.com, bhutchings@...arflare.com,
	andi@...stfloor.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, herbert@...dor.apana.org.au,
	jesse.brandeburg@...el.com, shemminger@...tta.com
Subject: Re: [RFC v2: Patch 1/3] net: hand off skb list to other cpu to
 submit to upper layer

From: Tom Herbert <therbert@...gle.com>
Date: Fri, 13 Mar 2009 10:06:56 -0700

> You'll definitely want to look at the hardware provided hash.  We've
> been using a 10G NIC which provides a Toeplitz hash (the one defined
> by Microsoft) and a software RSS-like capability to move packets from
> an interrupting CPU to another for processing.  The hash could be used
> to index to a set of CPUs, but we also use the hash as a connection
> identifier to key into a lookup table to steer packets to the CPU
> where the application is running based on the running CPU of the last
> recvmsg.  Using the device provided hash in this manner is a HUGE win,
> as opposed to taking cache misses to get 4-tuple from packet itself to
> compute a hash.  I posted some patches a while back on our work if
> you're interested.

I never understood this.

If you don't let the APIC move the interrupt around, the individual
MSI-X interrupts will steer packets to individual specific CPUS and as
a result the scheduler will migrate tasks over to those cpus since the
wakeup events keep occuring there.
--
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