Created attachment 376697 [details] xend.log Description of problem: In a host with 4G memory,I create a PV guest with 512M memory.I set mammem as 1024M when I create the PV guest. But when I try to enlarge the memory size via xm mem-set, Domain0 just not balloon out memory so that the memory size of PV guest doesn`t change as requested. Version-Release number of selected component (if applicable): xen-3.0.3-94.el5 How reproducible: Always Steps to Reproduce: 1. List free memory size of host: # xm info | grep free free_memory : 512 2. Create PV guest: In the config file of PV guest: memory = 512 maxmem = 1024 Create PV guest via xm create: # xm cr /etc/xen/test_pv Using config file "/etc/xen/test_pv". file /root/pv.img Started domain PvDomain 3. Check free memory size of host after creating PV guest: # xm info | grep free free_memory : 0 4. Check memory information of PV guest: # xm li Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 3409 4 r----- 71.7 PvDomain 2 511 4 -b---- 7.2 # xm li 2 -l | grep maxmem (maxmem 1024) 5. Change memory size of PV guest via xm mem-set: # xm mem-set 2 1500 6. Check memory size of PV guest: In the host: # xm li 2 Name ID Mem(MiB) VCPUs State Time(s) PvDomain 2 512 4 -b---- 12.7 # cat /proc/xen/balloon Current allocation: 3490816 kB Requested target: 3490816 kB Low-mem balloon: 133532 kB High-mem balloon: 0 kB Driver pages: 1024 kB Xen hard limit: ??? kB In the guest: # cat /proc/xen/balloon Current allocation: 525096 kB Requested target: 1536000 kB Low-mem balloon: 531672 kB High-mem balloon: 0 kB Driver pages: 208 kB Xen hard limit: 525096 kB Actual results: Domain0 don`t balloon out memory when DomainU request Expected results: Domain0 balloon out memory when DomainU request Additional info:
Yeah, this is the way it is supposed to work. The behavior is a bit surprising, and has tripped up people before, but I'm not sure we can reasonably change it this late in RHEL-5's life. The correct procedure is to: # xm mem-set 0 1024 # xm mem-set <guest> <memory> I think the best we can do here is to write a kbase article about it. Chris Lalancette
Currently, Domain0 doesn`t automatically balloon down when DomainU balloon up. So close this bug. *** This bug has been marked as a duplicate of bug 219724 ***