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Date: Tue, 08 Apr 2008 23:00:28 -0700 From: Mike Travis <travis@....com> To: Ingo Molnar <mingo@...e.hu> CC: Andi Kleen <andi@...stfloor.org>, Cyrill Gorcunov <gorcunov@...il.com>, "H. Peter Anvin" <hpa@...or.com>, LKML <linux-kernel@...r.kernel.org>, Yinghai Lu <yhlu.kernel@...il.com>, Eric Dumazet <dada1@...mosbay.com> Subject: Re: bootmem allocator Ingo Molnar wrote: > * Andi Kleen <andi@...stfloor.org> wrote: > >>> hm, bootmem allocator is supposed to clear memory. We have a couple >>> of places that rely on that. >> I was actually considering to change that for the GB pages hugetlbfs >> patchkit, because memset for 1G is a little slow and not needed (will >> be cleared later anyways) and it might be a problem for very large >> systems with a lot of such pages at boot. > > changing the default behavior of bootmem alloc to be non-clearing is a > really bad idea that will only cause unrobustness. The proper approach > is to add an _opt-in_ API that does not clear memory > (bootmem_alloc_dontclear() or whatever), available to callers that know > it for sure that they dont need the clearing. Yes, changing the default of bootmem_alloc is a bad idea. I just changed a bunch of static arrays to bootmem alloc's and it was pointed out early that not only does bootmem_alloc clear memory, but also panics if it's not available. > Also take into account that alloc_bootmem_low() : > - calls panic() if not enough memory > - already clears allocated memory > Signed-off-by: Eric Dumazet <dada1@...mosbay.com> A specialized call to bootmem_alloc probably needs it's own API... ;-) Thanks, Mike -- 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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