Messages in this thread | | | Date | Mon, 14 Nov 2011 18:39:29 +0100 | Subject | Re: [PATCH] perf_events: fix and improve x86 event scheduling | From | Stephane Eranian <> |
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On Mon, Nov 14, 2011 at 5:00 PM, Peter Zijlstra <peterz@infradead.org> wrote: > On Mon, 2011-11-14 at 15:26 +0100, Stephane Eranian wrote: >> There is an edge from the source to all the events. >> There is an edge from all the counters to the sync. >> There is an edge between an event and a counter, if >> it can count the event. >> >> The capacity of any edge is 1. > > Ah indeed. > > So that gives: > > E = e+e*c+c ~= O(c^2); since e<=c > V = 2+e+c ~= O(c) > > Then going by: > > http://en.wikipedia.org/wiki/Maximum_flow_problem > > we have to stay away from Edmonds-Karp. > > Ford-Fulkerson would end up being O(E * c) = O(c^3), since max |f| is c. > Which is pretty much identical to all these O(V^2 E) = O(c^3) as well. > > Dinitz blocking flow with dynamic trees looks more interesting at O(c^2 > log(c)). Push relabel with dynamic trees looks to be best at O(c^2), > since V^2/E ends up being c^2/c^2 = 1. > > Creating the graph itself will be O(c^2) as well, due to E. > I think we are in the special case of a bi-partite graph with unit capacities, thus the complexity can be reduced even more.
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