Hi Noam, 1) Both machines have 2GB of memory and are using 200Mb of it..
I think the problem is not memory 2) no weird errors, of any kind in the dmesg or /var/log The newer machine is very new :) I wrote 1 year, it is actually 3 months, I don't think its a hardware malfunction, but I could be wrong 3) What is iostat / sar ? how would you measure those values? I thought hdparm was accurate, I guess it isn't On Tue, Sep 8, 2009 at 4:13 PM, Noam Meltzer <[email protected]> wrote: > Hi, > > I would try to focus on the I/O issue. (best guess I have so far) > Some things I would check: > 1. file system cache. mayeb the file is already in cache? maybe all memory > is allocated and no free ram for cache? etc. > 2. dmesg and/or /var/log/messages -> check if there are weird I/O errors. > (same for raid controller if any) > 3. iostat / sar. check the disk performance. see the numbers, especially > throughput, service time & average wait looks reasonable. > > > > On Tue, Sep 8, 2009 at 3:30 PM, Noam Rathaus <[email protected]>wrote: > >> Hi Noam, >> >> Yes I looked with strace. >> >> The most notable difference is the read time on files (new HD) >> 0.047210 read(7, " <= 0)\n {\n $numLimit = 10;\n }\n\n "..., 4096) >> >> Instead of (old HW) >> 0.001462 read(6, "owItem = $1;\n\n my $RowItems = $s"..., 4096) = 4096 >> >> That is 40 times slower (it is the same file being opened) >> >> I have no idea why there is such a difference >> >> hdparm on the old: >> hdparm -t /dev/sda >> >> /dev/sda: >> Timing buffered disk reads: 190 MB in 3.02 seconds = 62.87 MB/sec >> >> hdparm on the new: >> # hdparm -t /dev/sda >> >> /dev/sda: >> Timing buffered disk reads: 314 MB in 3.01 seconds = 104.22 MB/sec >> >> >> On Tue, Sep 8, 2009 at 3:02 PM, Noam Meltzer <[email protected]> wrote: >> >>> Did you try to check with strace ? >>> >>> 2009/9/8 Noam Rathaus <[email protected]> >>> >>>> 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? >>>> >>>> Thanks, >>>> Noam Rathaus >>>> >>>> _______________________________________________ >>>> Linux-il mailing list >>>> [email protected] >>>> http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il >>>> >>>> >>> >> >
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