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Date: Wed, 14 Jan 2009 15:41:15 +0100 From: Frederik Deweerdt <frederik.deweerdt@...og.eu> To: Andi Kleen <andi@...stfloor.org> Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>, Ravikiran G Thirumalai <kiran@...lex86.org>, tglx@...utronix.de, hpa@...or.com, linux-kernel@...r.kernel.org Subject: Re: [patch] tlb flush_data: replace per_cpu with an array On Wed, Jan 14, 2009 at 10:08:11AM +0100, Andi Kleen wrote: > > > > It also would save some memory > > > on most distros out there (Ubuntu x86_64 has NR_CPUS=64 by default). > > As pointed out several times this claim in the changelog is incorrect. > Please fix it. > > A correct description would be: > > - This patch wastes memory of one configured cache line for each CPU > on systems with less than 8 cores (e.g. 896 bytes on a 1 core system > with CONFIG_GENERIC_CPU/ cache line size 128) > It saves some memory on systems with more than 8 cores (one cache > line size for each core above 8) To be fair, it also depends on whenever HOTPLUG_CPU is on or not (if it is we allocate NR_CPUS percpu sections). In that case, which is Ubuntu's and Fedora's, we do save memory. This would make for a fairly long changelog, how about a link to this thread, and removing the NR_CPUS bit? Regards, Frederik > > -Andi > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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