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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