Messages in this thread | | | Date | Tue, 19 Jan 2010 10:26:38 +0200 | From | Gleb Natapov <> | Subject | Re: [PATCH v6] add MAP_UNLOCKED mmap flag |
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On Tue, Jan 19, 2010 at 10:07:07AM +0200, Pekka Enberg wrote: > Hi Gleb, > > On Tue, Jan 19, 2010 at 9:52 AM, Gleb Natapov <gleb@redhat.com> wrote: > >> It would be probably useful if you could point us to the application > >> source code that actually wants this feature. > >> > > This is two line patch to qemu that calls mlockall(MCL_CURRENT|MCL_FUTURE) > > at the beginning of the main() and changes guest memory allocation to > > use MAP_UNLOCKED flag. All alternative solutions in this thread suggest > > that I should rewrite qemu + all library it uses. You see why I can't > > take them seriously? > > Well, that's not going to be portable, is it, so the application KVM is not portable ;) and that is what my main interest is.
> design would still be broken, no? Did you try using (or extending) > posix_madvise(MADV_DONTNEED) for the guest address space? It seems to After mlockall() I can't even allocate guest address space. Or do you mean instead of mlockall()? Then how MADV_DONTNEED will help? It just drops page table for the address range (which is not what I need) and does not have any long time effect.
> me that you're trying to use a big hammer (mlock) when a polite hint > for the VM would probably be sufficient for it do its job. > I what to tell to VM "swap this, don't swap that" and as far as I see there is no other way to do it currently.
-- Gleb.
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