From mboxrd@z Thu Jan 1 00:00:00 1970 From: mel@skynet.ie (Mel Gorman) Date: Wed, 14 Mar 2007 19:49:41 +0000 Subject: Re: [QUICKLIST 4/6] x86_64: Single Quicklist Message-Id: <20070314194941.GA21862@skynet.ie> List-Id: References: <20070311020923.19905.49260.sendpatchset@schroedinger.engr.sgi.com> <20070311020944.19905.87599.sendpatchset@schroedinger.engr.sgi.com> <200703110854.05799.ak@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Andi Kleen , linux-kernel@vger.kernel.org, ak@suse.com, linux-ia64@vger.kernel.org, holt@sgi.com, mpm@selenic.com On (11/03/07 09:44), Christoph Lameter didst pronounce: > On Sun, 11 Mar 2007, Andi Kleen wrote: > > > This and i386 version are ok to me, although it might be better to just > > finish __GFP_ZERO support to do this. > > This would not work for pgds on i386 and x86_64 > > GFP_ZERO support the way I have done it in the past would mean another set > of buddy lists in the page allocator and another issue with fragmentation. > So I have stayed away from it although patches exist in my archives (See > my ftp.kernel.org archive). I haven't checked this in a while but when we experimented with keeping zero'd pages on separate lists before, the performance sucked. I haven't looked at it in a *long* time though. > > Maybe we could implemento limited GFP_ZERO support by just keeping an > additional per cpu list of pages? I imagine that adding an additional per-cpu list will not be welcome. > The issue with that one is that a page > may grow cold on that list. And that growing cold appeared to hurt before. It could be checked out again though. The anti-fragmentation breaks out the buddy lists already and has the ability to search the per-cpu lists for pages of an appropriate type. I'll try and find an hour or two to hack something together to see what it looks like but I suspect it'll still be a performance loss. At least then though, we can see if quicklists are a better plan or not. > One usually want the page to be hot in the > cache when it is allocated. This is different for page table pages. Page > table pages are typically sparsely accessed. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab