Jes Sorensen wrote: > Zhang, Xiantao wrote: >>> From 697d50286088e98da5ac8653c80aaa96c81abf87 Mon Sep 17 00:00:00 >>> 2001 >> From: Xiantao Zhang <xiantao.zhang@xxxxxxxxx> >> Date: Mon, 31 Mar 2008 09:50:24 +0800 >> Subject: [PATCH] KVM:IA64: Implement smp_call_function_mask for ia64 >> >> This function provides more flexible interface for smp >> infrastructure. Signed-off-by: Xiantao Zhang >> <xiantao.zhang@xxxxxxxxx> > > Hi Xiantao, > > I'm a little wary of the performance impact of this change. Doing a > cpumask compare on all smp_call_function calls seems a little > expensive. Maybe it's just noise in the big picture compared to the > actual cost of the IPIs, but I thought I'd bring it up. > Keep in mind that a cpumask can be fairly big these days, max NR_CPUS > is currently 4096. For those booting a kernel with NR_CPUS at 4096 on > a dual CPU machine, it would be a bit expensive. > > Why not keep smp_call_function() the way it was before, rather than > implementing it via the call to smp_call_function_mask()? Hi, Jes I'm not aware of the performance impact before. If the worst case occurs, it need 64 comparisions ? Maybe keeping old smp_call_function is better ? Xiantao > > ------------------------------------------------------------------------ - > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services for > just about anything Open Source. > http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketp lace > _______________________________________________ > kvm-devel mailing list > kvm-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/kvm-devel -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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