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Date: Sat, 12 Jan 2008 17:52:26 -0800 From: Stephen Hemminger <shemminger@...ux-foundation.org> To: Andi Kleen <ak@...e.de> Cc: netdev@...r.kernel.org, linux-kerne@...r.kernel.org Subject: Re: [PATCH/RFC] synchronize_rcu(): high latency on idle system On Sat, 12 Jan 2008 19:35:58 +0100 Andi Kleen <ak@...e.de> wrote: > On Saturday 12 January 2008 18:51:35 Benjamin LaHaise wrote: > > On Sat, Jan 12, 2008 at 03:37:59AM +0100, Andi Kleen wrote: > > > > And yes, the > > > > network stack shouldn't call synchronize_rcu() quite so much, but fixing that > > > > is a little more involved. > > > > > > ... but the correct solution. > > > > There has to be at least 1 synchronize_rcu() or equivalent in the > > unregister_netdev() path. I suspect the easiest way to fix it might be to > > use call_rcu() to actually free the network device, as anything else will > > limit performance of single threaded teardown (ie, when an l2tp daemon > > gets terminated via kill -9). This means an API change that exposes > > rcu for unregister_netdev(). > > The call_rcu() could be in free_netdev() couldn't it? I think it should be in netdev_unregister_kobject(). But that would only get rid of one of the two calls to synchronize_rcu() in the unregister_netdev. The other synchronize_rcu() is for qdisc's and not sure if that one can be removed? -- Stephen Hemminger <stephen.hemminger@...tta.com> -- 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
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