Messages in this thread | | | Subject | Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags | From | Matt Mackall <> | Date | Tue, 28 Apr 2009 13:34:31 -0500 |
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On Tue, 2009-04-28 at 11:11 -0700, Tony Luck wrote: > On Tue, Apr 28, 2009 at 1:33 AM, Wu Fengguang <fengguang.wu@intel.com> wrote: > > 1) FAST > > > > It takes merely 0.2s to scan 4GB pages: > > > > ./page-types 0.02s user 0.20s system 99% cpu 0.216 total > > OK on a tiny system ... but sounds painful on a big > server. 0.2s for 4G scales up to 3 minutes 25 seconds > on a 4TB system (4TB systems were being sold two > years ago ... so by now the high end will have moved > up to 8TB or perhaps 16TB). > > Would the resulting output be anything but noise on > a big system (a *lot* of pages can change state in > 3 minutes)?
Bah. The rate of change is proportional to #cpus, not #pages. Assuming you've got 1024 processors, you could run the scan in parallel in .2 seconds still.
It won't be an atomic snapshot, obviously. But stopping the whole machine on a system that size is probably not what you want anyway.
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