Messages in this thread | | | Date | Mon, 27 Aug 2007 18:46:12 +0000 | From | Mike Travis <> | Subject | Re: [PATCH 0/6] x86: Reduce Memory Usage and Inter-Node message traffic (v2) |
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On Sat, 25 Aug 2007, Andi Kleen wrote:
> On Fri, Aug 24, 2007 at 05:50:18PM -0700, Siddha, Suresh B wrote: > > On Fri, Aug 24, 2007 at 03:26:54PM -0700, travis@sgi.com wrote: > > > Previous Intro: > > > > Thanks for doing this. > > > > > In x86_64 and i386 architectures most arrays that are sized > > > using NR_CPUS lay in local memory on node 0. Not only will most > > > (99%?) of the systems not use all the slots in these arrays, > > > particularly when NR_CPUS is increased to accommodate future > > > very high cpu count systems, but a number of cache lines are > > > passed unnecessarily on the system bus when these arrays are > > > referenced by cpus on other nodes. > > > > Can we move cpuinfo_x86 also to per cpu area? Though critical run > > I worry how much impact that would be? boot_cpu_data is quite > widely used. >
I looked at this and it would be a big memory savings. But I haven't yet analyzed the various accesses to verify that we can cleanly move the structure, and that we don't suffer a bunch of tlb misses because accesses are primarily from node 0.
More info soon.
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