/srv/irclogs.linaro.org/2011/09/21/#linaro-mm-sig.txt

=== benjiG1 is now known as benjiG
benjiGmszyprow: hi14:54
mszyprowbenjiG: hello14:54
benjiGmszyprow: on CMA reserved area we can only allocate movable pages, right ?14:55
mszyprowbenjiG: right14:55
mszyprowbenjiG: kernel cannot allocate non-movable pages from CMA regions14:55
benjiGmszyprow: ok,  but which kind of kernel operations allocate movable pages ? it isn't kmalloc ...14:56
mszyprowbenjiG: allocation of disk buffers, page cache, etc14:57
mszyprowbenjiG: I'm not sure about vmalloc14:57
mszyprowbenjiG: kmalloc defintely allocates pages as non-movable14:58
robclarkuserspace memory?   (although I guess that could later be pinned w/ get_user_pages())14:58
mszyprowrobclark: yes, all userspace memory is movable14:58
mszyprowunless pinned14:58
robclarkwhat happens when you pin but the page is from CMA?14:59
robclarkdoes get_user_pages() fail?  or page is migrated?14:59
mszyprowrobclark: frankly I have no idea yet, but this is really a good question14:59
mszyprowrobclark: I will investigate this case and let you know14:59
robclarkhmm.. ok, thx..14:59
robclarkI prefer kernel allocated buffers for DMA or passing to DSP or other coprocessors..15:00
benjiGmszyprow: so a cmd like "find . -name *" can request the allocation of movable pages ?15:00
robclark(esp. when we start dealing w/ a15 and LPAE)15:00
robclarkbenjiG, any disk I/O could.. although I guess that depends on the filesystem15:01
mszyprowbenjiG: yes, most of the memory will be allocated as movable15:01
mszyprowbenjiG: besides some filesystem internal helper structures and structures like new process descriptor15:02
mszyprowI need to go home now, see You tomorrow15:04
benjiGmszyprow: ok thx15:04

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