andreas1234567 has asked for the wisdom of the Perl Monks concerning the following question:
- First has 40 GB RAM (IBM 3850 M2 / x3950 M2, PCI-E)
- Second has 64 GB RAM (IBM x3950, PCI-X)
- OS Red Hat Enterprise Linux 4.7
- linux kernel 2.6.9-89 x86_64
- perl 5.8.9
- identical processor, disks, etc.
use warnings; use strict; use JSON::XS; use Benchmark qw(cmpthese); my $coder = JSON::XS->new->ascii->pretty->allow_nonref; my $hashref = { one => 1, two => 2, three => 3, four => { nested => 'b +ird' } }; my $arrayref = [ 'one', 'two', 'three', 'four', 'five', 'six' ]; # cmpthese can be used both ways as well cmpthese( -1, { 'enc+dec hashref ' => sub { $coder->decode( $coder->encode( $hashref ) ) }, 'enc+dec arrayref ' => sub { $coder->decode( $coder->encode( $arrayref ) ) }, } ); __END__
[me@first ~]$ ./perl-json-test.pl Rate enc+dec hashref enc+dec arrayref enc+dec hashref 344063/s -- -22% enc+dec arrayref 438597/s 27% -- [me@second ~]$ ./perl-json-test.pl Rate enc+dec hashref enc+dec arrayref enc+dec hashref 153121/s -- -24% enc+dec arrayref 200972/s 31% --
Do any of the honorable monks have made similar observations or even reasonable explanation to why the machine with the most memory is the slower one?
Update 1: Actually, I have 4 machines of which 2 are pairwise identical. Each machine behaves identically as its twin.
Update 2 : Thanks for helpful replies. As I have remote access only to the machines in question, I can't experiment as broadly as I otherwise would have, but I'll surely update this thread once I get some results. I have asked the services provider to reduce physical memory down to 16 Gb.
Update 3 : It turns the machines were not identical after all (see top), and that reducing the memory down to 16 Gb did not significantly change the benchmarks. Whether or not the PCI bus type can account for the huge difference in overall performance is unknown.
No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]
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Re: Less is more? 40G memory twice as fast as 64G
by Herkum (Parson) on Feb 12, 2010 at 14:51 UTC | |
by ikegami (Patriarch) on Feb 12, 2010 at 15:42 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by zentara (Archbishop) on Feb 12, 2010 at 12:43 UTC | |
by afoken (Chancellor) on Feb 14, 2010 at 12:11 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by BrowserUk (Patriarch) on Feb 12, 2010 at 15:59 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by davis (Vicar) on Feb 12, 2010 at 18:44 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by Anonymous Monk on Feb 12, 2010 at 13:33 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by MidLifeXis (Monsignor) on Feb 12, 2010 at 14:49 UTC | |
Re: Less is more? 40G memory twice as fast as 64G
by Marshall (Canon) on Feb 14, 2010 at 15:26 UTC |