Jamal & Stephen, I found BSS-hash paper you mentioned and have browsed it briefly. The issue "may end sending all your packets to one cpu" might be dealt with by cpu hash (srcip + dstip) % nr_cpus, plus checking cpu balance periodically, shift cpu by an extra seed value?
Any way, the cpu hash code must not be too expensive because every incoming packet hits the path. We are going to do further study on this BSS thing. __do_IRQ has a tendency to collect same IRQ on different CPUs into one CPU when NIC is busy(by IRQ_PENDING & IRQ_INPROGRESS control skill). so, dispatch the load to SMP here may be good thing(?). Thanks. John Ye ----- Original Message ----- From: "jamal" <[EMAIL PROTECTED]> To: "Stephen Hemminger" <[EMAIL PROTECTED]> Cc: "john ye" <[EMAIL PROTECTED]>; "David Miller" <[EMAIL PROTECTED]>; <netdev@vger.kernel.org>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Wednesday, September 26, 2007 6:22 AM Subject: Re: [PATCH: 2.6.13-15-SMP 3/3] network: concurrentlyrunsoftirqnetwork code on SMP > On Tue, 2007-25-09 at 09:03 -0700, Stephen Hemminger wrote: > > > There is a standard hash called RSS, that many drivers support because it is > > used by other operating systems. > > I think any stateless/simple thing will do (something along the lines > what 802.1ad does for trunk, a 5 classical five tuple etc). > > Having solved the reordering problem in such a stateless way introduces > a loadbalancing setback; you may end sending all your packets to one cpu > (a problem Mr Ye didnt have when he was re-orderding ;->). > > cheers, > jamal > > - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
