Perl slowness

[Arie Skliarouk]

Try to measure disk seek time on both disks:

 time echo $(dd if=/dev/sda of=/dev/null count=1 bs=512; dd if=/dev/sda
of=/dev/null count=1 bs=1 skip=200049647116;)

Replace the last number with size of the disk - several bytes (check using
fdisk -l).
The operation would give meaningful result only the first time you run it.

If someone has better way to check disk seek speed, please share.

Are you running the script as root?
Do you get the same slow results each time you run it or only the first
time?
Is there disk thrashing during startup?

--
Arie



2009/9/8 Noam Rathaus <noamr at beyondsecurity.com>

> Everything is on the /dev/sda
>
> And local
>
> That is not the answer...
>
>
> On Tue, Sep 8, 2009 at 3:28 PM, Gabor Szabo <szabgab at gmail.com> wrote:
>
>> 2009/9/8 Noam Rathaus <noamr at beyondsecurity.com>:
>> > Hi,
>> >
>> > I have two machines, their hardware is not identical, but their
>> installation
>> > is.
>> >
>> > One is a 3 years old DELL server, while the other is a 1 year old
>> server.
>> >
>> > One is running 2.6.26-2-686 while the other 2.6.30-1-686
>> >
>> > What I am seeing is slow startup - emphasis on startup, the code works
>> fast
>> > once its running - of perl scripts
>> >
>> > Even the smallest perl script such as this:
>> > ===
>> > #!/usr/bin/perl
>> >
>> > use lib '/usr/local/MySystem/lib';
>> >
>> > use DB;
>> >
>> > ===
>> >
>> > Take 7 seconds to start, in comparison to 0.030secods
>> >
>> > If I don't use the "use DB;" which my package
>> >
>> > It loads fast
>> >
>> > I am trying to figure out why, I checked the HD speeds via hdparam, the
>> > newer server is 1.5 times faster 103MB/sec
>> >
>> > I tried to see what libraries were being used, used strace, but I can't
>> see
>> > something "big" that is causing the delay.
>> >
>> > The "use DB;" can be replaced with any other "custom" library package I
>> > wrote, they all take 2-7 seconds to load, while on the other machine it
>> > takes negligible time
>> >
>> > Does someone have a "thread" to cling to?
>> >
>>
>>
>> A wide guess is that it is searching the @INC and on one system
>> @INC points to a slow disk maybe via NFS ?
>>
>> Gabor
>>
>>
>
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