#5749: GHC 7.0.4 Performance Regression (Possibly Vector)
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Reporter: sanketr | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version: 7.0.4
Resolution: invalid | Keywords: performance, vector
Os: Linux | Architecture: x86_64 (amd64)
Failure: Runtime performance bug | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related: 5623
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Changes (by simonmar):
* status: new => closed
* resolution: => invalid
Comment:
I suspect this caused the change:
commit 5e195173cd1921e838eb977f649ef178dff00415
{{{
Author: Simon Marlow <[email protected]>
Date: Mon Sep 13 13:38:18 2010 +0000
Use clock_gettime (if available) to measure the process CPU time
This is much more accurate than getrusage, which was giving misleading
results when trying to time very quick operations like a minor GC.
}}}
Your program is spending a lot of time in the kernel:
{{{
real 0m1.331s
user 0m0.467s
sys 0m0.679s
}}}
and it looks like in 6.12 the method we used for measuring CPU time did
not include time spent in the kernel (`sys` time in the `time` output
above), whereas now it does.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5749#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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