Messages in this thread | | | Date | Thu, 08 Dec 2005 11:13:06 +1100 | From | Nick Piggin <> | Subject | Re: [RFC 1/3] Framework for accurate node based statistics |
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Christoph Lameter wrote: > On Thu, 8 Dec 2005, Nick Piggin wrote: > > >>Christoph Lameter wrote: >> >>>On Wed, 7 Dec 2005, Nick Piggin wrote: >>> >>>>Sorry, I think I meant: why don't you just use the "add all counters >>>>from all per-cpu of the node" in order to find the node-statistic? >>> >>>which function is that? >>> >> >>I'm thinking of get_page_state_node... but that's not quite the same >>thing. I guess sum all per-CPU counters from all zones in the node, >>but that's going to be costly on big machines. > > > The per cpu counters count when a cpu did an allocation. They do not count > on which node the allocation was done and are thereofre not useful to > determine the memory use on one node. >
Yes, not that exact function of course.
> >>So I'm not sure, I guess I don't have any bright ideas... there is the >>batching approach used by current pagecache_acct - is something like >>that not sufficient either? > > > The framework provides a similar approach by keeping differential > counters for each processor. >
But the accounting delay has the unbounded error problem that the batching approach does not.
-- SUSE Labs, Novell Inc.
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