HPVM dynamic memory won't resize

Rike255 — Mon, 07 Nov 2011 18:55:15 GMT

Hello,

I have a VM Guest (HPVM 4.2.5) configured as follows:

[Memory Details]
Total memory : 32 GB
Minimum memory limit : 512 MB
Maximum memory limit : 64 GB
Reserved memory : 64 MB
Minimum reserved limit : 32 MB
Maximum reserved limit : 64 GB
VHPT Size : 1 MB

[Dynamic Memory Information]
Type : driver
Minimum memory : 1024 MB
Target memory : 30778 MB
Memory entitlement : Not specified
Maximum memory : 32768 MB
Current memory : 32762 MB
Comfortable minimum : 12538 MB
Total memory : 32762 MB
Free memory : 12264 MB
Available memory : 12577 MB
Memory pressure : 0
Memory chunksize : 65536 KB
AMR chunksize : 256 MB
Driver Mode(s) : STARTED ENABLED GUESTCTL
AMR state : DISABLED

When I run an hpvmmodify -x ram_target=30G the command returns no errors and I see the ram target change (shown above), but the memory never decreases. In the documentation it says it can take a long time if the memory is fragmented, but this guest is doing almost no work and has a lot of memory space available.

#hpvmmgmt -x ram_target=30G
Attempting to decrease memory from 32762 MB to 30720 MB.
Successfully began to change ram_target to 30720 MB.

# hpvmmgmt -V -l ram
[Dynamic Memory Information]
=======================================
Type : driver
Minimum memory : 1024 MB
Target memory : 30778 MB
Maximum memory : 32768 MB
Current memory : 32762 MB
Comfortable minimum : 12538 MB
Boot memory : 32762 MB
Free memory : 12264 MB
Available memory : 12577 MB
Memory pressure : 0
Memory chunksize : 65536 KB
Driver Mode(s) : STARTED ENABLED GUESTCTL

I waited a good 10 minutes with no changes to the current memory. I see an error in syslog that says:

vmunix: hpvmdynmem: unable to reach target memory size of 30778 MB after 60 seconds, resulting memory size is 32762 MB.

I can't figure out why I can't resize this VM. Anyone else run into this?

Thanks,

Ryan

Re: HPVM dynamic memory won't resize

Dave Olker — Thu, 24 Jun 2021 13:44:54 GMT

Hi Ryan,

I wonder if this is a situation where the memory on your VM Host has become fragmented. Looking at the HPVM 4.3 Admin Guide:

8.10.3 Troubleshooting Dynamic Memory Problems

This section describes how to solve problems in the use of dynamic memory.

8.10.3.1 Dynamic Memory Restrictions

• If the virtual machine memory has become fragmented , attempting to reduce the size of the virtual machine might fail or might take a very long time. If you cannot reduce the size the virtual machine might fail or might take a very long time. If you cannot reduce the size of the virtual machine to the desired size, end the operation by setting a new target size.

Are you setting the kctune parameter "base_pagesize" to 64 on your VM Host system? That can really reduce memory fragmentation issues on the VM Host and help with dynamic memory resizing issues.

Hope this helps,

Dave

topic HPVM dynamic memory won't resize in Operating System - HP-UX

HPVM dynamic memory won't resize

Re: HPVM dynamic memory won't resize