On Wed, 8 Jul 2009 03:00:27 +0200 Ivan Warren <i...@vmfacility.fr> wrote:
> cmm-1 (arch/s390/mm/cmm.c) uses SMSGs to communicate with the VMRM > service virtual machine. The VMRM will instruct the guest to release its > pages using good ole Diag 10.. nothing fancy here.. diag 10 actively tells z/VM that the page is free. > cmma (arch/s390/mm/page_states.c) uses the B9AB instruction to indicate > to CP which pages linux no longer needs.. It uses the standard Linux MM > mechanism to be instructed to do so. (page_free()).. The only diff > between Diag 10 and B9AB is that a page marked "Unused" with B9AB will > generate an Addressing Exception (PIC 5) if you attempt to access it, > while Diag 10 won't do that. The B9AB instruction will mark a page as free in the pgste. That does not cause a sie exit to z/VM which means z/VM doesn't know the page is free until it does a page scan for the guest. So you won't see an immediate effect in the z/VM page counts. If z/VM needs memory it will eventually find the unused pages and the page count will drop belately. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
