From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 15 Dec 2008 15:16:47 +0100 From: Nick Piggin Subject: Re: [rfc][patch] SLQB slab allocator Message-ID: <20081215141647.GC30163@wotan.suse.de> References: <20081212002518.GH8294@wotan.suse.de> <20081214230407.GB7318@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Linux Kernel Mailing List , Linux Memory Management List , bcrl@kvack.org, list-linux-mm@kvack.org List-ID: On Mon, Dec 15, 2008 at 08:02:47AM -0600, Christoph Lameter wrote: > On Mon, 15 Dec 2008, Nick Piggin wrote: > > > > Does this mean that SLQB is less efficient than SLUB for off node > > > allocations? SLUB can do off node allocations from the per cpu objects. It > > > does not need to make the distinction for allocation. > > > > I haven't measured them, but that could be the case. However I haven't > > found a workload that does a lot of off-node allocations (short lived > > allocations are better on-node, and long lived ones are not going to > > be so numerous). > > A memoryless node is a case where all allocations will be like that. Yes. Can the memoryless node revert to a default (closest) memory node? > > That's more complexity, though. Given that objects are often hot when > > they are freed, and need to be touched after they are allocated anyway, > > the simple queue seems to be reasonable. > > Yup. > > > This case does improve the database score by around 1.5-2%, yes. I > > don't know what you mean exactly, though. What case, and what do you > > mean by bad cache unfriendly programming? I would be very interested > > in improving that benchmark of course, but I don't know what you > > suggest by keeping cachelines hot in the right way? > > What I was told about the database test is that it collects lists of > objects from various processors that are then freed on a different > processor. This means all objects are cache cold. Well it's running an unmodified kernel... the database itself I guess is just submitting direct-IO requests from multiple processes to multiple disks. The objects should be pretty warm on the freeing CPU, but yes it would take a cacheline transfer at some level I guess. -- 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