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Re: NPTL <=> NGPT performance test results with pingpong benchmark



Ingo Molnar wrote:
> 
> On Wed, 4 Dec 2002, Liu, Bing Wei wrote:
> 
> > Has anyone tried some performance tests to compare certain aspect of
> > nptl and ngpt? I found a program named pingpong in a white paper at
> > http://wwws.sun.com/software/whitepapers/solaris9/multithread.pdf, which
> > was devised to evaluate the efficiency of lock/unlock operation and
> > context switch.
> >
> > With a SMP machine (2xPIII 933MHz w/ 512MB), on top of kernel 2.5.49,
> > I run a round of tests with both ngpt 2.0.4 and nptl 0.10.
> 
> i've organized your results into a bit more compact form:
> 
>                                 NGPT 2.0.4     NPTL 0.10    ( speedup )
> -----------------------------------------------------------------------
>  pp32                             15.2 sec       4.5 sec    (   230%  )
>  pp32 -s system                   16.3 sec       4.5 sec    (   260%  )
>  pp32 -n 4                        54.0 sec      30.8 sec    (    70%  )
>  pp32 -n 4 -p shared             174.1 sec      27.3 sec    (   530%  )
>  pp32 -n 4000 -i 100 -S 32768    211.4 sec      10.1 sec    (  1990%  )
> -----------------------------------------------------------------------
> 
> what you measured is in line with our preliminary tests, where we found a
> 4x speedup over NGPT. (and an 8x speedup over LinuxThreads.)
> 
 
When I ran this program on a 4-way SMP system (4xPIII 700MHZ w/1GB) on 
top of 2.5.49 kernel, using NPTL 0.10 (latest glibc), the results are
real strange.

pp32 -n 128 -i 100 takes more than 40 sec
pp32 -n 128 -i 10 also takes 35sec
pp32 -n 4000 -i 100 -S 32768 didn't complete (hangs or takes long time)

As the iteration (-i) goes down, it behaves badly.
Am I missing something?


- Saurabh





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