profiling

Difference in performance of compiled accelerate code ran from ghci and shell

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I investigated accelerate and accelerate-cuda and put some debug code to measure a time both under ghci and in a compiled, optimised version. Results are below, you can see stack trace and execution times. ghci run $ ghc -O2 -dynamic -c -threaded Main.hs && ghci GHCi, version 7.8.3: http://www.haskell.org/ghc/ 😕 for help … Loading package … Read more

What is the System objects in chrome javascript memory profiler

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According to the JSHeapSnapshot.js implementation in Chromium, as mentioned in a comment by wOxxOm, a comparison for a given node distance to 100000000 is performed (distances[ordinal] >= WebInspector.HeapSnapshotCommon.baseSystemDistance, where WebInspector.HeapSnapshotCommon.baseSystemDistance = 100000000) and if passing, the size is accumulated into the System segment of the pie chart. The commit that last modifies this value mentions, … Read more

What restriction is perf_event_paranoid == 1 actually putting on x86 perf?

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In this case CPU event refers to monitoring events per CPU rather than per task. For perf tools this restricts the usage of -C, –cpu= Count only on the list of CPUs provided. Multiple CPUs can be provided as a comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. In … Read more

gprof : How to generate call graph for functions in shared library that is linked to main program

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gprof won’t work, you need to use sprof instead. I found these links helpful: How to use sprof? http://greg-n-blog.blogspot.com/2010/01/profiling-shared-library-on-linux-using.html Summary from the 2nd link: Compile your shared library (libmylib.so) in debug (-g) mode. No -pg. export LD_PROFILE_OUTPUT=`pwd` export LD_PROFILE=libmylib.so rm -f $LD_PROFILE.profile execute your program that loads libmylib.so sprof PATH-TO-LIB/$LD_PROFILE $LD_PROFILE.profile -p >log See the … Read more

What is -no-pie used for?

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That flag is telling gcc not to make a position independent executable (PIE). PIE is a precondition to enable address space layout randomization (ASLR). ASLR is a security feature where the kernel loads the binary and dependencies into a random location of virtual memory each time it’s run.

How to profile PostgreSQL Database?

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“Keep an eye on” and “profile” are two quite different tasks in my view. For profiling (not a live view on what’s going on right now, but to see which queries take most time etc), check out pgFouine: http://pgfouine.projects.postgresql.org/ This will let you see which queries are resource intensive, and take appropriate action: Add missing … Read more