Mailinglist Archive: opensuse-factory (808 mails)

[Cristian Rodríguez <crrodriguez@xxxxxxxxxxxx>]

On 30/08/11 05:58, Ruediger Meier wrote:
> On Tuesday 30 August 2011, Claudio Freire wrote:
> > > BTW you can see that user time is 15% higher with pigz so
> > > compression per core cycle is worse.
> >
> > That's called cache pressure. It happens when more than one process
> > is running. Run four gzips concurrently, you'll probably experience
> > the same increase.
>
> Yes, ...
> ... and ouf course you will see that gzip has more throughput in any 
> case while the system is less on load:
>
> # 4 x gzip in parallel
> rudi@quant:/tmp> time  ( for i in `seq 1 4` ; do  gzip  -c hist.csv & 
> done ;wait )   > /dev/null
>
> real   0m30.500s
> user   1m59.311s
> sys    0m0.978s
>
> # 4 x pigz in parallel in parallel
> rudi@quant:/tmp> time  ( for i in `seq 1 4` ; do  
> ~rudi/tmp/pigz-2.1.6/pigz -c hist.csv & done ;wait )   > /dev/null
>
> real   0m35.164s
> user   2m18.944s
> sys    0m1.236s
>
> # 4 x pigz sequential
> -bash: syntax error near unexpected token `)'
> rudi@quant:/tmp> time  ( for i in `seq 1 4` ; do  
> ~rudi/tmp/pigz-2.1.6/pigz -c hist.csv ;done ;wait )   > /dev/null
>
> real   0m35.147s
> user   2m16.647s
> sys    0m3.398s

is /tmp and  in ram ? otherwise your "tests" are meaningless, because
you are then measuring I/O aka. the wrong thing!



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