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Message-ID: <Pine.LNX.4.64.0710301155240.12746@schroedinger.engr.sgi.com> Date: Tue, 30 Oct 2007 11:58:08 -0700 (PDT) From: Christoph Lameter <clameter@....com> To: Andrew Morton <akpm@...ux-foundation.org> cc: matthew@....cx, linux-kernel@...r.kernel.org, linux-mm@...ck.org, penberg@...helsinki.fi, Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>, linux-arch@...r.kernel.org Subject: Re: [patch 08/10] SLUB: Optional fast path using cmpxchg_local On Tue, 30 Oct 2007, Andrew Morton wrote: > Let's cc linux-arch: presumably other architectures can implement cpu-local > cmpxchg and would see some benefit from doing so. Matheiu had a whole series of cmpxchg_local patches. Ccing him too. I think he has some numbers for other architectures. > The semantics are "atomic wrt interrutps on this cpu, not atomic wrt other > cpus", yes? Right. > Do you have a feel for how useful it would be for arch maintainers to implement > this? IOW, is it worth their time? That depends on the efficiency of a cmpxchg_local vs. the interrupt enable/ disable sequence on a particular arch. On x86 this yields about 50% so it doubles the speed of the fastpath. On other architectures the cmpxchg is so slow that it is not worth it (ia64 f.e.) - 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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