From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx184.postini.com [74.125.245.184]) by kanga.kvack.org (Postfix) with SMTP id 4BD426B002B for ; Tue, 16 Oct 2012 14:36:45 -0400 (EDT) Received: by mail-ie0-f169.google.com with SMTP id 10so12887781ied.14 for ; Tue, 16 Oct 2012 11:36:44 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <507DA245.9050709@am.sony.com> References: <1350392160.3954.986.camel@edumazet-glaptop> <507DA245.9050709@am.sony.com> Date: Tue, 16 Oct 2012 15:36:44 -0300 Message-ID: Subject: Re: [Q] Default SLAB allocator From: Ezequiel Garcia Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Tim Bird Cc: Eric Dumazet , David Rientjes , Andi Kleen , Linux Kernel Mailing List , "linux-mm@kvack.org" , "celinux-dev@lists.celinuxforum.org" On Tue, Oct 16, 2012 at 3:07 PM, Tim Bird wrote: > On 10/16/2012 05:56 AM, Eric Dumazet wrote: >> On Tue, 2012-10-16 at 09:35 -0300, Ezequiel Garcia wrote: >> >>> Now, returning to the fragmentation. The problem with SLAB is that >>> its smaller cache available for kmalloced objects is 32 bytes; >>> while SLUB allows 8, 16, 24 ... >>> >>> Perhaps adding smaller caches to SLAB might make sense? >>> Is there any strong reason for NOT doing this? >> >> I would remove small kmalloc-XX caches, as sharing a cache line >> is sometime dangerous for performance, because of false sharing. >> >> They make sense only for very small hosts. > > That's interesting... > > It would be good to measure the performance/size tradeoff here. > I'm interested in very small systems, and it might be worth > the tradeoff, depending on how bad the performance is. Maybe > a new config option would be useful (I can hear the groans now... :-) > It might be worth reminding that very small systems can use SLOB allocator, which does not suffer from this kind of fragmentation. Ezequiel -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org