High DNS EXT

[Klem]

I have bad performances on my server since several days. mysql requests are very slow, even my vm backups are twice longer. However the resources are not saturated.
I checked proxmox performances with pveperf and I had the following results :

CPU BOGOMIPS: 55998.56
REGEX/SECOND: 873303
HD SIZE: 466.65 GB (/dev/md1)
BUFFERED READS: 895.69 MB/sec
AVERAGE SEEK TIME: 0.17 ms
FSYNCS/SECOND: 291.36
DNS EXT: 351.08 ms

DNS EXT seems very high (on another server I get 8.92ms).
I don't find explanation about this value. Can it be linked to my slow down ?

 

[Stoiko Ivanov]

DNS EXT checks how fast your system does DNS resolution for an (nonexistant) external domain.

* How is your /etc/resolv.conf setup?
* does DNS resolution work (somewhat fast)?

If not this could explain that things are slow (DNS is used quite heavily - even where you might not expect it)

I hope this helps!

 

[Klem]

I found the problem this morning.
Cpus were scaled down to 800Mhz instead of 3.5G

I got this line on syslog but I don't know what can cause this.
kernel: [9486277.982336] perf: interrupt took too long (5026 > 5011), lowering kernel.perf_event_max_sample_rate to 39750