Messages in this thread | | | Date | Thu, 25 Sep 2008 17:39:31 +0200 | From | Thomas Hellström <> | Subject | Re: [patch] mm: pageable memory allocator (for DRM-GEM?) |
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Keith Packard wrote: > On Thu, 2008-09-25 at 00:19 -0700, Thomas Hellström wrote: > >> If data is >> dirtied in VRAM or the page(s) got discarded >> we need new pages and to set up a copy operation. >> > > Note that this can occur as a result of a suspend-to-memory transition > at which point *all* of the objects in VRAM will need to be preserved in > main memory, and so the pages aren't really 'freed', they just don't > need to have valid contents, but the system should be aware that the > space may be needed at some point in the future. > > Actually, I think the pages must be allowed to be freed, and that we don't put a requirement on "pageable" to keep swap-space slots for these pages. If we hit an OOM-condition during suspend-to-memory that's bad, but let's say we required "pageable" to keep swap space slots for us, the result would perhaps be that another device wasn't able to suspend, or a user-space program was killed due to lack of swap-space prior to suspend.
I'm not really sure what's the worst situation, but my feeling is that we should not require swap-space to be reserved for VRAM, and abort the suspend operation if we hit OOM. That would, in the worst case, mean that people with non-UMA laptops and a too small swap partition would see their battery run out much quicker than they expected...
/Thomas
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