I am having the same problem about performance issue, well perhaps it is
because I have slow memory, I have a P4 HT with 256mb DDR 400 and HD 40 gb,
today I reinstalled the -OS Centos 5.1 final with gnome. I don´t know if it
is okay to have only 4 megs of ram free. Perhaps I need more ram because I
am using gnome I ask because is the first time I probe linux in my desktop
pc, I note that is acting slow what do you think?
There are some ways to free up some memory in order to better adjust my os
with a minimum amount of ram like 256mb. This pc is for learning, so I don´t
know if it deserves buying more memory but your experience is more than
mine.
Thanks in advance.
George from Uruguay.
-----Mensaje original-----
De: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] En nombre
de Alfred von Campe
Enviado el: Miércoles, 13 de Febrero de 2008 12:00 p.m.
Para: CentOS mailing list
Asunto: Re: Strange performance issues under CentOS 5.1
On Feb 12, 2008, at 21:57, William L. Maltby wrote:
> Check BIOS settings? For memory, CAS etc. the same? Disk hardware the
> same and specified identically?
Pretty much all the same. They are standard Lenovo desktops, with a
3.4 GHz Core 2 Duo and 3 GB of memory (the BIOS doesn't let the OS
address more than 3 GB).
> Presumming that nothing is found there, install system accounting
> packages and run some SAR reports. You may see a clue in them.
I will try that next.
> Any "tweaks" on the old system you forgot to apply on the new?
> Elevator,
> buffer flush interval changes, etc?
Nope, it's a vanilla kickstart install. I am using the same scripts
(with only slight variations) to build both the 4.x and 5.x systems.
I didn't do anything to "tune" the 4.x systems. That's one of the
things I like about CentOS (and RHEL for that matter): they just work
out of the box. A build (make/gcc) is typically CPU bound. I don't
understand how it can get only 11% of the CPU. That's unheard of.
> Any other noticeable things on there that may cause it? Presume the
> slowdown is caused by a process that you are not looking at. "Hangs"
> while some other process is waiting or tying up the CPU. Try running
> top.
There is nothing else running on the systems at the time. I have
lots of terminal windows open on the 4.x system, but I am ssh'ed into
the 5.x system and nobody else is logged in. If anything, the 4.x
system should be slower since there are many more things running on it.
>
> I notice an execve shows on the new one that is not in the old. One
> says
> "hmmm....".
The execve is in the other as well, just a few lines further down
(i.e., it didn't make the cut when I did the "head strace.log").
> What does swapon -s show?
CentOS 4.6:
Filename Type Size
Used Priority
/dev/mapper/VolGroup00-LogVol00 partition 4095992
210592 -1
CentOS 5.1:
Filename Type Size
Used Priority
/dev/mapper/VolGroup00-LogVol00 partition 3047416
120 -1
> Is the system "seeing" the same amount of memory "available" or have
> BIOS settings in one reduced available?
CentOS 4.6:
MemTotal: 3113612 kB
MemFree: 24868 kB
Buffers: 23164 kB
Cached: 2428508 kB
SwapCached: 136108 kB
Active: 1685808 kB
Inactive: 1257004 kB
HighTotal: 2226560 kB
HighFree: 1088 kB
LowTotal: 887052 kB
CentOS 5.1:
MemTotal: 3114452 kB
MemFree: 2722528 kB
Buffers: 84592 kB
Cached: 174804 kB
SwapCached: 0 kB
Active: 187084 kB
Inactive: 137220 kB
HighTotal: 2226560 kB
HighFree: 1972860 kB
LowTotal: 887892 kB
> If all new equipment on the new one, open her up and reseat all
> connections, PCI cards and mem sticks. Make sure all power connectors
> are well seated to MB and drives.
I will double check that. I may also try to install 4.6 on the HW
that is currently running 5.1 and see if there is a problem. With my
kickstart scripts I can have the system up and running in less than
30 minutes. That is probably the best next step to rule out any HW
issues. I'll do that as soon as I get into the office.
> Front side bus and memory speeds set the same in BIOS?
Should be.
> That's all I can think of that may be even remotely related ATM
Thanks for all the excellent suggestions, Bill.
Alfred
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