Hi
I did not any "benchmarks", but I upgraded our smp-box from 2.0.36 to
2.2.5-ac7 and
it seems to be much faster.
The cpu load went nearly always to 100% under 2.0.36 with heavy load on
the machine;
now the system seems to be more "fresher" and cpu load varies from 0 to
70% under
the same load.
My system (single cpu) at home behaves the same way.
I think to compare both kernelversions by doing a gzip does not give you
much
information of the systems behaviour under heavy load (much users).
Greetings, Dietmar
Alan Watson wrote:
>
> I've had two disconcerting experiences lately. Last month,
> we upgraded a Sun from Solaris 2.6 to Solaris 2.7; it got
> faster. Last week, I upgraded my dual 450 MHz PII machine
> from RedHat 5.2 (2.0.36) to RedHat 6.0 (2.2.5-15smp); it got
> slower.
>
> I'm working on a two-stage image compression method. The
> image is quantized in one process and fed into gzip or bzip2
> using popen(). In sh terms, this is "process1 | process2".
> This used to parallelize quite nicely, with one process
> running on each processor, but now about the best I can get
> is 120% CPU usage, often less. Overall, the pipe is slower.
>
> You can see this for yourself, by piping two gzips or bzip2s
> together:
>
> $ dd if=/dev/urandom of=random bs=1M count=5
> 5+0 records in
> 5+0 records out
>
> $ time sh -c "gzip -9 <random | gzip -9 >/dev/null"
> 5.57user 0.14system 0:04.72elapsed 120%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (355major+215minor)pagefaults 0swaps
>
> $ time sh -c "bzip2 -1 <random | bzip2 -1 >/dev/null"
> 53.01user 0.11system 0:47.52elapsed 111%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (379major+585minor)pagefaults 0swaps
>
> I don't think this is just latency (i.e., the second process
> in the pipe waiting for data from the first), since "bzip2
> -1" will consume and produce data in roughly 100k chunks and
> so will have a latency of only about half a second. Dropping
> into single-user mode and stopping the raid daemons do not
> help.
>
> Any great ideas about how to get this back to more like 200%
> CPU usage?
>
> Alan
>
> (To add insult to injury, I'm still using the binaries for
> gzip/gunzip from 5.2, as they are about 20% faster than the
> ones shipped with 6.0. Go figure.)
> --
> Dr Alan Watson
> Instituto de Astronom�a UNAM
> -
> Linux SMP list: FIRST see FAQ at http://www.irisa.fr/prive/mentre/smp-faq/
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--
"For those about to rock - we salute you!"
Dietmar Stein, Systemadministrator UNIX/Linux
http://home.t-online.de/home/dstein2203
[EMAIL PROTECTED], [EMAIL PROTECTED]
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