From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [Pv-ops][PATCH] Netback multiple tasklet support Date: Thu, 10 Dec 2009 10:01:10 -0800 Message-ID: <4B213766.7030201@goop.org> References: <4FA716B1526C7C4DB0375C6DADBC4EA342A7A7E951@LONPMAILBOX01.citrite.net> <4FA716B1526C7C4DB0375C6DADBC4EA342A7A7E95E@LONPMAILBOX01.citrite.net> <4B182D87.6030901@goop.org> <4B187513.80003@goop.org> <4B200727.8040000@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Xu, Dongxiao" Cc: Steven Smith , Ian Pratt , "xen-devel@lists.xensource.com" , Ian Campbell List-Id: xen-devel@lists.xenproject.org On 12/09/09 19:29, Xu, Dongxiao wrote: >> Also, is it worth making it a tunable? Presumably it needn't scale >> exactly with the number of dom0 cpus; if you only have one or two gbit >> interfaces, then you could saturate that pretty quickly with a small >> number of cpus, regardless of how many domains you have. >> > How many CPUs are serving for the NIC interface is determined by how > interrupt is delivered. If system only has two gbit interfaces, and they > delivier interrupts to CPU0 and CPU1, then the case is: two CPUs handle > two tasklets. Other CPUs are idle. The group_nr just defines the max > number of tasklets, however it doesn't decide how tasklet is handled by > CPU. > So does this mean that a given vcpu will be used to handle the interrupt if happens to be running on a pcpu with affinity for the device? Or that particular devices will be handled by particular vcpus? >> I've pushed this out in its own branch: >> xen/dom0/backend/netback-tasklet; please post any future patches >> against this branch. >> > What's my next step for this netback-tasklet tree merging into xen/master? > Hm, well, I guess: * I'd like to see some comments Keir/Ian(s)/others that this is basically the right approach. It looks OK to me, but I don't have much experience with performance in the field. o does nc2 make nc1 obsolete? * Testing to make sure it really works. Netback is clearly critical functionality, so I'd like to be sure we're not introducing big regressions J