Mark Post wrote:
Of course not. CMM and CMMA are designed interfaces between Linux and z/VM. Their whole purpose in life is to let the two work together on virtual memory management.
Precisely ! if the linux kernel deems the page to be 'free' (and dropping a page from buffer/cache should do that - but then again, maybe not - and then I'll go back to my corner), and CMMA is available and functional (that is, activated and you have the right level of z/VM with the right PTFs), then the kernel Memory Manager (mm/page_alloc) should call the CMMA arch_free_page() In turn, arch/s390/mm/page_states.c[arch_free_page] (page_states.c IS CMMA) calls the z/VM EXTRACT_AND_SET_STORAGE_ATTRIBUTE (B9AB) instruction to indicate to CP that the page is no longer needed. arch_free_state sets the page to the 'Unused' state (as per 6.1.4.4 of the z/VM 5.4 CP Programing services) Setting the page to an 'Unused' state should make any physical page associated with the virtual page eligible to be reused for other purpose as well as free any associated paging slot as the guest operating system is declaring by that action that it won't be needing that page until it puts it back into a 'Stable' state. Thus achieving the intended result. You were stating : MP: - "Just because Linux no longer treats those pages as being used doesn't mean z/VM sees them as free." What I am saying is that, on the contrary, when linux treats those pages as no longer being in use, z/VM *WILL* see them as free ! ... CMM is different.. It uses a service virtual machine and is a completely different mechanism.. ... Then again, it's probably a better idea to let Linux and z/VM handle caching, buffering, paging and whatnot using their own heuristics than using a sledgehammer approach to flush the cache at regular intervals. --Ivan ---------------------------------------------------------------------- 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
smime.p7s
Description: S/MIME Cryptographic Signature
