That doesn't sound right. I use DHAT extensively and expect a slowdown of
perhaps 50:1, maybe less. What you're describing is a slowdown factor of
at least several thousand.
Bear in mind though that (1) V sequentialises thread execution, which wil
make a big difference if the program is heavily multithreaded, and (2)
I suspect dhat's scheme of looking up all memory accesses in an AVL tree
(of malloc'd blocks) doesn't scale all that well if you have tens of
millions of blocks.
Can you run it on a smaller workload?
J
On 26/05/2020 09:21, Paul FLOYD wrote:
Hi
I'm running DHAT on what I consider to be a relatively small example. Standalone the executable runs in a bit under 10 minutes. Based on the CPU time that we print after every 10% of progress, under DHAT the same executable is going to take about 422 hours - about two and a half weeks.
Does anyone have any ideas what could be causing it to be so slow? Indeed, is this the sort of slowdown that I should be expecting with DHAT? The executable is intensive in both memory and floating point. Probably not helping matters, the data structures that I want to look at are over 1kB in size so I tweaked the HISTOGRAM_SIZE_LIMIT to bump it up to 2kb.
On the DHAT side, I have thought of trying to use some macro hackery to try to inline the avl comparator function calls. Otherwise I don't have much in the way of other ideas, and DHAT doesn't have any cli options to tweak things.
A+
Paul
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