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Message-Id: <200803112041.09217.nickpiggin@yahoo.com.au> Date: Tue, 11 Mar 2008 20:41:09 +1100 From: Nick Piggin <nickpiggin@...oo.com.au> To: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> Cc: Christoph Lameter <clameter@....com>, linux-kernel@...r.kernel.org Subject: Re: [RFC PATCH] Implement slub fastpath with sequence number On Tuesday 11 March 2008 20:31, Mathieu Desnoyers wrote: > Here is a new version that works. tested on x86. tweaked the bitmasks > into unions to remove operations from the critical path, but I tried to > keep that clean. It applies on vm.git HEAD. > > It allows the cmpxchg_local to detect object re-use by keeping a counter in > the freeoffset MSBs. > > Whenever an object is freed in the cpu slab cache, the counter is > incremented. Whenever the alloc/free slow paths are modifying the offset or > freebase, the sequence counter is also incremented. It is used to make sure > we know if freebase has been modified in an interrupt nested over the fast > path. Wow. I applaud the effort to micro optimise things ;) But I hope this doesn't get merged until macro-regressions in SLUB are verified to be fixed. It's pretty clear that SLUB's problem is not fastpath performance, so I think this would be premature optimisation. -- 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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