Hello ,
After upgrading the system from CentOS 7.2.1511 to CenOS 7.3.1611 I see that the average processing time has increased from 5-7% to 12-15% (doubled). Not critical but it is not pleasant. Server as KVM with 5 virtual machines. Someone noticed something similar? If so, how to fix that?
Thx.
On Wed, Jan 18, 2017 at 2:34 PM, Subscriber ml-lists@agoris.net.ua wrote:
Hello ,
After upgrading the system from CentOS 7.2.1511 to CenOS 7.3.1611 I see that the average processing time has increased from 5-7% to 12-15% (doubled). Not critical but it is not pleasant. Server as KVM with 5 virtual machines. Someone noticed something similar? If so, how to fix that?
Thx.
In the mean time, if you have not disabled it, you should find some collected statistics from sysstat/sar. Look at the sarXX files under /var/log/sa. They should be kept for 30 day by default in CentOS 7. So you can compare cpu, mem, I/O profiles before and after the upgrade. If you have access to Red Hat documents you can look also here: https://access.redhat.com/articles/325783
or in general some articles like this: https://www.blackmoreops.com/2014/06/18/sysstat-sar-examples-usage/ and to create pdf graphics with kSar https://www.thomas-krenn.com/en/wiki/Linux_Performance_Analysis_using_kSar
HIH, Gianluca
Hello Gianluca,
Wednesday, January 18, 2017, 3:54:15 PM, you wrote:
In the mean time, if you have not disabled it, you should find some collected statistics from sysstat/sar. Look at the sarXX files under /var/log/sa. They should be kept for 30 day by default in CentOS 7.
Unfortunately, on that host such statistics is disabled.
So you can compare cpu, mem, I/O profiles before and after the upgrade. If you have access to Red Hat documents you can look also here: https://access.redhat.com/articles/325783
or in general some articles like this: https://www.blackmoreops.com/2014/06/18/sysstat-sar-examples-usage/ and to create pdf graphics with kSar https://www.thomas-krenn.com/en/wiki/Linux_Performance_Analysis_using_kSar
HIH, Gianluca _______________________________________________ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Hello Subscriber,
Thursday, January 19, 2017, 4:44:04 PM, you wrote:
Hello Gianluca,
Wednesday, January 18, 2017, 3:54:15 PM, you wrote:
In the mean time, if you have not disabled it, you should find some collected statistics from sysstat/sar. Look at the sarXX files under /var/log/sa. They should be kept for 30 day by default in CentOS 7.
Unfortunately, on that host such statistics is disabled.
But I collect such statistics in Zabbix. And the numbers and graphs indicate an increase in the load on the CPU (ie System time).
On 01/19/2017 06:54 AM, Subscriber wrote:
But I collect such statistics in Zabbix. And the numbers and graphs indicate an increase in the load on the CPU (ie System time).
"load" has another meaning in the context of POSIX system performance counters. I'm pretty sure you're talking about CPU utilization and not "load", right?
Hello Gordon,
Thursday, January 19, 2017, 5:09:29 PM, you wrote:
On 01/19/2017 06:54 AM, Subscriber wrote:
But I collect such statistics in Zabbix. And the numbers and graphs indicate an increase in the load on the CPU (ie System time).
"load" has another meaning in the context of POSIX system performance counters. I'm pretty sure you're talking about CPU utilization and not "load", right?
Definitely.
Subscriber wrote:
Hello Gianluca,
Wednesday, January 18, 2017, 3:54:15 PM, you wrote:
In the mean time, if you have not disabled it, you should find some collected statistics from sysstat/sar. Look at the sarXX files under /var/log/sa. They should be kept for 30 day by default in CentOS 7.
Unfortunately, on that host such statistics is disabled.
<snip> That's surprising. That's such an old, low-level daemon/reporting tool.... Was it disabled deliberately? And why?
mark
Hello m,
Thursday, January 19, 2017, 5:17:48 PM, you wrote:
In the mean time, if you have not disabled it, you should find some collected statistics from sysstat/sar. Look at the sarXX files under /var/log/sa. They should be kept for 30 day by default in CentOS 7.
Unfortunately, on that host such statistics is disabled.
<snip> That's surprising. That's such an old, low-level daemon/reporting tool.... Was it disabled deliberately? And why?
Heritage from the old admin to me.
On 01/18/2017 05:34 AM, Subscriber wrote:
Someone noticed something similar?
How is your storage arranged, and what kind of IO patterns do those VMs have?
During recent testing, I found that the read performance of software RAID volumes was worse under 7.3 than it was under 7.2. Most other IO had improved significantly:
https://plus.google.com/+GordonMessmer/posts/eSe6iNmk1Fs?sfc=false
Hello Gordon,
Wednesday, January 18, 2017, 11:52:35 PM, you wrote:
On 01/18/2017 05:34 AM, Subscriber wrote:
Someone noticed something similar?
How is your storage arranged,
It is software RAID1 + LVM
and what kind of IO patterns do those VMs have?
Do not quite understand. What do you mean?
During recent testing, I found that the read performance of software RAID volumes was worse under 7.3 than it was under 7.2. Most other IO had improved significantly:
https://plus.google.com/+GordonMessmer/posts/eSe6iNmk1Fs?sfc=false
On 01/19/2017 06:29 AM, Subscriber wrote:
and what kind of IO patterns do those VMs have?
Do not quite understand. What do you mean?
What at the VMs doing? Are they entirely idle? Are they doing light work, mostly reading from disks? If they're not generating disk IO, then that's not related. However, during a recent set of benchmarks, I found that disk reads were slower under 7.3 than under 7.2. That might be specific to the system I tested, or it might be related to the change you're seeing.
Hello Gordon,
Thursday, January 19, 2017, 4:57:48 PM, you wrote:
On 01/19/2017 06:29 AM, Subscriber wrote:
and what kind of IO patterns do those VMs have?
Do not quite understand. What do you mean?
What at the VMs doing?
Its gateway from local network to Internet
Are they entirely idle?
At work time - No. Another time in most - Yes
Are they doing light work, mostly reading from disks? If they're not generating disk IO, then that's not related.
Well no. They are not loaded the disc(s). No heavy for write operations.
-
Gianluca Cecchi -
Gordon Messmer -
m.roth＠5-cent.us -
Subscriber