I am still running CentOS 4.6 on our production systems, but I am starting to plan the upgrade to CentOS 5.1. I have one test system running 5.1 that is the exact same hardware configuration as my 4.6 test system. One of our builds runs about 6 times slower on the 5.1 system, even though is uses less overall CPU time. I first suspected something wrong with the disk, but the results from bonnie++ show that the 5.1 system is slightly faster:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- -- Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec % CP /sec %CP centos4.6 16G 35933 10 21301 5 46507 6 41.8 0
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- -- Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec % CP /sec %CP centos5.1 16G 42015 14 21179 5 49863 4 91.6 0
Then I ran the build with "/usr/bin/time --verbose", and here are the results (first 4.6 then 5.1):
Command being timed: "make" User time (seconds): 32.15 System time (seconds): 3.52 Percent of CPU this job got: 99% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:35.88
Command being timed: "make" User time (seconds): 22.05 System time (seconds): 3.11 Percent of CPU this job got: 11% Elapsed (wall clock) time (h:mm:ss or m:ss): 3:31.35
As you can see from the above, there is a lot of idle time on the 5.1 system. Finally, I ran the build with "strace -c", and here are the top ten lines of that output (again, 4.6 first and then 5.1):
% time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 53.81 16.804147 54916 306 58 waitpid 34.75 10.853461 82851 131 wait4 5.29 1.650844 9 177706 154581 open 1.61 0.503701 15 34408 read 0.91 0.283706 15 18607 write 0.60 0.185894 12 14919 10364 stat64 0.52 0.163340 10 16495 9079 access 0.47 0.146933 7 20581 mmap2
% time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 60.07 15.173924 52687 288 58 waitpid 38.50 9.724412 83831 116 wait4 0.54 0.135194 7 19199 10705 access 0.36 0.090850 54 1681 1334 execve 0.27 0.067686 5 14423 10570 stat64 0.11 0.027676 1 24832 read 0.09 0.022339 0 155810 135765 open 0.03 0.007617 159 48 unlink
Any suggestions as to what could possible be causing this? I am fresh out of other ideas to try.
Alfred
On Tue, 2008-02-12 at 21:15 -0500, Alfred von Campe wrote:
I am still running CentOS 4.6 on our production systems, but I am starting to plan the upgrade to CentOS 5.1. I have one test system running 5.1 that is the exact same hardware configuration as my 4.6 test system. One of our builds runs about 6 times slower on the 5.1 system, even though is uses less overall CPU time. I first suspected something wrong with the disk, but the results from bonnie++ show that the 5.1 system is slightly faster:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- -- Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec % CP /sec %CP centos4.6 16G 35933 10 21301 5 46507 6 41.8 0
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- -- Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec % CP /sec %CP centos5.1 16G 42015 14 21179 5 49863 4 91.6 0
Then I ran the build with "/usr/bin/time --verbose", and here are the results (first 4.6 then 5.1):
Command being timed: "make" User time (seconds): 32.15 System time (seconds): 3.52 Percent of CPU this job got: 99% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:35.88 Command being timed: "make" User time (seconds): 22.05 System time (seconds): 3.11 Percent of CPU this job got: 11% Elapsed (wall clock) time (h:mm:ss or m:ss): 3:31.35As you can see from the above, there is a lot of idle time on the 5.1 system. Finally, I ran the build with "strace -c", and here are the top ten lines of that output (again, 4.6 first and then 5.1):
% time seconds usecs/call calls errors syscall
53.81 16.804147 54916 306 58 waitpid 34.75 10.853461 82851 131 wait4 5.29 1.650844 9 177706 154581 open 1.61 0.503701 15 34408 read 0.91 0.283706 15 18607 write 0.60 0.185894 12 14919 10364 stat64 0.52 0.163340 10 16495 9079 access 0.47 0.146933 7 20581 mmap2
% time seconds usecs/call calls errors syscall
60.07 15.173924 52687 288 58 waitpid 38.50 9.724412 83831 116 wait4 0.54 0.135194 7 19199 10705 access 0.36 0.090850 54 1681 1334 execve 0.27 0.067686 5 14423 10570 stat64 0.11 0.027676 1 24832 read 0.09 0.022339 0 155810 135765 open 0.03 0.007617 159 48 unlink
Any suggestions as to what could possible be causing this? I am fresh out of other ideas to try.
Check BIOS settings? For memory, CAS etc. the same? Disk hardware the same and specified identically?
Presumming that nothing is found there, install system accounting packages and run some SAR reports. You may see a clue in them.
Any "tweaks" on the old system you forgot to apply on the new? Elevator, buffer flush interval changes, etc?
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.
I notice an execve shows on the new one that is not in the old. One says "hmmm....".
What does swapon -s show?
Is the system "seeing" the same amount of memory "available" or have BIOS settings in one reduced available?
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.
Front side bus and memory speeds set the same in BIOS?
That's all I can think of that may be even remotely related ATM
Alfred
<snip sig stuff>
HTH
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
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@centos.org [mailto:centos-bounces@centos.org] En nombre de Alfred von Campe Enviado el: Miércoles, 13 de Febrero de 2008 12:00 p.m. Para: CentOS mailing list Asunto: Re: [CentOS] 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
_______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On Feb 13, 2008 5:35 PM, Masters IT Gmail mastersit.com@gmail.com wrote:
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.
George,
I'm fairly confident your system is swapping and thereby causing the issue, you can check it out with dstat for example. A old 40 GB harddrive is not improving the situation, I'm sure iostat (part of the sysstat RPM package) will tell you by showing a high await value. You need at least 512 MB to run just Gnome in a resonable paste, you may want to consider some lightweight window manager such as xfce4, blackbox etc.
- Nicolas
Masters IT Gmail wrote:
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?
I think you should have at least double the memory of what you have. Even 512MB is light for a modern GNOME desktop (I recently re-built an older Athlon 1300 w/512MB ram for my mother and 512MB wouldn't get the system responsive enough for me to use on a regular basis, though she was used to slower computers anyways so it was still an improvement).
Or don't use gnome, there are plenty of other window managers out there(I'm a fan of Afterstep for example) that provide less things but at the same time use far less resources.
Of course if you try to run stuff like firefox, open office etc you'll still run into a memory wall pretty quick. Opera is a good choice for low memory systems. I'm sure there are others as well.
nate
nate
Thanks nate! Know I really understand how this Works, okay maybe a little more than yesterday, hehe. So I am going to buy some extra memory in order to keep with my Linux study, thanks for all I really appreciate you help.
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de nate Enviado el: Miércoles, 13 de Febrero de 2008 02:54 p.m. Para: centos@centos.org Asunto: RE: [CentOS] Strange performance issues under CentOS 5.1
Masters IT Gmail wrote:
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?
I think you should have at least double the memory of what you have. Even 512MB is light for a modern GNOME desktop (I recently re-built an older Athlon 1300 w/512MB ram for my mother and 512MB wouldn't get the system responsive enough for me to use on a regular basis, though she was used to slower computers anyways so it was still an improvement).
Or don't use gnome, there are plenty of other window managers out there(I'm a fan of Afterstep for example) that provide less things but at the same time use far less resources.
Of course if you try to run stuff like firefox, open office etc you'll still run into a memory wall pretty quick. Opera is a good choice for low memory systems. I'm sure there are others as well.
nate
nate
_______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Now that I understand that i need more ram after i add this ram to my centos, what I need to do in order to increase my swap partition, thanks in advance.
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de nate Enviado el: Miércoles, 13 de Febrero de 2008 02:54 p.m. Para: centos@centos.org Asunto: RE: [CentOS] Strange performance issues under CentOS 5.1
Masters IT Gmail wrote:
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?
I think you should have at least double the memory of what you have. Even 512MB is light for a modern GNOME desktop (I recently re-built an older Athlon 1300 w/512MB ram for my mother and 512MB wouldn't get the system responsive enough for me to use on a regular basis, though she was used to slower computers anyways so it was still an improvement).
Or don't use gnome, there are plenty of other window managers out there(I'm a fan of Afterstep for example) that provide less things but at the same time use far less resources.
Of course if you try to run stuff like firefox, open office etc you'll still run into a memory wall pretty quick. Opera is a good choice for low memory systems. I'm sure there are others as well.
nate
nate
_______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Masters IT Gmail wrote:
Now that I understand that i need more ram after i add this ram to my centos, what I need to do in order to increase my swap partition, thanks in advance.
How much swap do you currently have? You may not need to increase swap at all.
If you do - I haven't tried this method in CentOS (or any OS) but it should work:
https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143fc380f84d7ea92...
It creates a swap file instead of a swap partition. Much easier than finding unpartitioned space ...
I have a swap file of 512mb because i was using 256mb, now i already have 512mb ram installed and the swap continue on 512mb, the system is acting better now.
System monitor says:
CPU History 3.0 or 4.0 % User Memory: 224mb of 495mb Used swap: 0 bytes of 512mb
I have running one windows of firefox while viewing in system monitor. Don't know if this values are okay I think they are normal but I don't have to much experience.
Do you think I need to make some change in swap partition like going to 1gb, if so, where can I find some help in doing that?
Thanks for your help.
George from Uruguay.
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de Michael A. Peters Enviado el: Miércoles, 13 de Febrero de 2008 06:07 p.m. Para: CentOS mailing list Asunto: Re: [CentOS] Upgrade ram and what to do with SWAP PARTITION ?
Masters IT Gmail wrote:
Now that I understand that i need more ram after i add this ram to my centos, what I need to do in order to increase my swap partition, thanks
in
advance.
How much swap do you currently have? You may not need to increase swap at all.
If you do - I haven't tried this method in CentOS (or any OS) but it should work:
https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143fc380f84d7ea92 03f16a596d0
It creates a swap file instead of a swap partition. Much easier than finding unpartitioned space ... _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Sorry i miss that link that you give me i am reading now thanks for the tip i am going to try. Thanks for all!
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de Michael A. Peters Enviado el: Miércoles, 13 de Febrero de 2008 06:07 p.m. Para: CentOS mailing list Asunto: Re: [CentOS] Upgrade ram and what to do with SWAP PARTITION ?
Masters IT Gmail wrote:
Now that I understand that i need more ram after i add this ram to my centos, what I need to do in order to increase my swap partition, thanks
in
advance.
How much swap do you currently have? You may not need to increase swap at all.
If you do - I haven't tried this method in CentOS (or any OS) but it should work:
https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143fc380f84d7ea92 03f16a596d0
It creates a swap file instead of a swap partition. Much easier than finding unpartitioned space ... _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Masters IT Gmail wrote:
Sorry i miss that link that you give me i am reading now thanks for the tip i am going to try. Thanks for all!
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de Michael A. Peters Enviado el: Miércoles, 13 de Febrero de 2008 06:07 p.m. Para: CentOS mailing list Asunto: Re: [CentOS] Upgrade ram and what to do with SWAP PARTITION ?
Masters IT Gmail wrote:
Now that I understand that i need more ram after i add this
ram to my
centos, what I need to do in order to increase my swap
partition, thanks in
advance.
How much swap do you currently have? You may not need to increase swap at all.
If you do - I haven't tried this method in CentOS (or any OS) but it should work:
https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143 fc380f84d7ea92 03f16a596d0
It creates a swap file instead of a swap partition. Much easier than finding unpartitioned space ...
Yes and with today's kernels it provides the same level of performance.
# dd if=/dev/zero of=/.swapfile bs=1M count=512
# mkswap /.swapfile
fstab: /.swapfile swap swap defaults 0 0
Or if you use lvm, turn swapoff the lv, lvresize the lv, mkswap the lv again, then swapon the lv and you have a larger swap, but the swapfile will at least be contiguous.
-Ross
______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.
Thanks again, i did the change, i follow this steps : http://www.linuxtopia.org/online_books/centos5/centos5_administration_guide/ centos5_s1-swap-adding.html#s2-swap-creating-file
But I setup bs=1M count=1024 this I learn it from: https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143fc380f84d7ea92 03f16a596d0 I like it more to do it that way.
Later I reboot my PC and run the command free, it seems that now I am using my newly created swap file, what a nice start. My linux experience is starting to like it more, thanks to all for your help, thoughts and time!
George from Uruguay.
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de Ross S. W. Walker Enviado el: Miércoles, 13 de Febrero de 2008 11:10 p.m. Para: CentOS mailing list Asunto: RE: [CentOS] Upgrade ram and what to do with SWAP PARTITION ?
Masters IT Gmail wrote:
Sorry i miss that link that you give me i am reading now thanks for the tip i am going to try. Thanks for all!
-----Mensaje original----- De: centos-bounces@centos.org [mailto:centos-bounces@centos.org] En nombre de Michael A. Peters Enviado el: Miércoles, 13 de Febrero de 2008 06:07 p.m. Para: CentOS mailing list Asunto: Re: [CentOS] Upgrade ram and what to do with SWAP PARTITION ?
Masters IT Gmail wrote:
Now that I understand that i need more ram after i add this
ram to my
centos, what I need to do in order to increase my swap
partition, thanks in
advance.
How much swap do you currently have? You may not need to increase swap at all.
If you do - I haven't tried this method in CentOS (or any OS) but it should work:
https://help.ubuntu.com/community/SwapFaq#head-75ffcb00cefe143 fc380f84d7ea92 03f16a596d0
It creates a swap file instead of a swap partition. Much easier than finding unpartitioned space ...
Yes and with today's kernels it provides the same level of performance.
# dd if=/dev/zero of=/.swapfile bs=1M count=512
# mkswap /.swapfile
fstab: /.swapfile swap swap defaults 0 0
Or if you use lvm, turn swapoff the lv, lvresize the lv, mkswap the lv again, then swapon the lv and you have a larger swap, but the swapfile will at least be contiguous.
-Ross
______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.
_______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
on 2/13/2008 5:59 AM Alfred von Campe spake the following:
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
I didn't see it but did you do a 'uname-a" on both systems to see if one is running a PAE kernel?
On Feb 13, 2008, at 11:37, Scott Silva wrote:
I didn't see it but did you do a 'uname-a" on both systems to see if one is running a PAE kernel?
No, that was not it. But I did finally track it down. There was one additional difference in the software configuration that I had forgotten about. The CentOS 5.1 system is in a different NIS domain and it has Kerberos enabled. We are going to move to an integrated NIS/AD environment to have a single sign-on for Windows and UNIX/ Linux, and I was planning to roll that out at the same time as CentOS 5.1. The performance issue went away when I used a local account to do the build, and also on another CentOS 5.1 system (on identical HW) that was bound to the old NIS domain.
Needless to say, we can not roll out CentOS 5.1 in the new NIS domain. I will be talking to the corporate IT folks tomorrow to track down what is causing this issue.
Thanks for all the help, Alfred
Alfred von Campe wrote:
On Feb 13, 2008, at 11:37, Scott Silva wrote:
I didn't see it but did you do a 'uname-a" on both systems to see if one is running a PAE kernel?
No, that was not it. But I did finally track it down. There was one additional difference in the software configuration that I had forgotten about. The CentOS 5.1 system is in a different NIS domain and it has Kerberos enabled. We are going to move to an integrated NIS/AD environment to have a single sign-on for Windows and UNIX/ Linux, and I was planning to roll that out at the same time as CentOS 5.1. The performance issue went away when I used a local account to do the build, and also on another CentOS 5.1 system (on identical HW) that was bound to the old NIS domain.
Needless to say, we can not roll out CentOS 5.1 in the new NIS domain. I will be talking to the corporate IT folks tomorrow to track down what is causing this issue.
Ah, I advise using Samba's winbind and the RID idmap backend. Winbind and it's local tdb cache is an order of magnitude faster then NIS and several orders of magnitude faster then nss_ldap.
I haven't tested Samba's ldap backend cause we have an AD domain here.
Winbind is a whole lot easier to setup and manages the kerberos keytab files too. We have winbind for user/group lookup and kerberos for authentication, works well and is fairly easy to automate setup through kickstart.
-Ross
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