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Date: Wed, 27 Dec 2006 13:52:46 +0000 From: "Catalin Marinas" <catalin.marinas@...il.com> To: "Ingo Molnar" <mingo@...e.hu> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH 2.6.20-rc1 00/10] Kernel memory leak detector 0.13 On 18/12/06, Ingo Molnar <mingo@...e.hu> wrote: > * Catalin Marinas <catalin.marinas@...il.com> wrote: > > I could also use a simple allocator based on alloc_pages [...] > > [...] It could be so simple that it would never need to free any > > pages, just grow the size as required and reuse the freed memleak > > objects from a list. > > sounds good to me. Please make it a per-CPU pool. We'll have to fix the > locking too, to be per-CPU - memleak_lock is quite a scalability problem > right now. (Add a memleak_object->cpu pointer so that freeing can be > done on any other CPU as well.) I did some simple statistics about allocations happening on one CPU and freeing on a different one. On a 4-CPU ARM system (and without IRQ balancing and without CONFIG_PREEMPT), these seem to happen in about 8-10% of the cases. Do you expect higher figures on other systems/configurations? As I mentioned in a different e-mail, a way to remove the global hash table is to create per-cpu hashes. The only problem is that in these 8-10% of the cases, freeing would need to look up the other hashes. This would become a problem with a high number of CPUs but I'm not sure whether it would overtake the performance issues introduced by cacheline ping-ponging in the single-hash case. Any thoughts? Thanks. -- Catalin - 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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