Messages in this thread | | | Date | Wed, 7 Oct 2009 22:47:18 +0200 | From | Gleb Natapov <> | Subject | Re: [PATCH][RFC] add MAP_UNLOCKED mmap flag |
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On Wed, Oct 07, 2009 at 10:10:17PM +0200, Olivier Galibert wrote: > On Wed, Oct 07, 2009 at 08:59:52PM +0200, Gleb Natapov wrote: > > On Wed, Oct 07, 2009 at 08:50:54PM +0200, Olivier Galibert wrote: > > > On Tue, Oct 06, 2009 at 02:16:03PM +0200, Gleb Natapov wrote: > > > > I did. It allows me to achieve something I can't now. Steps you provide > > > > just don't fit my needs. I need all memory areas (current and feature) to be > > > > locked except one. Very big one. You propose to lock memory at some > > > > arbitrary point and from that point on all newly mapped memory areas will > > > > be unlocked. Don't you see it is different? > > > > > > What about mlockall(MCL_CURRENT); mmap(...); mlockall(MCL_FUTURE);? > > > Or toggle MCL_FUTURE if a mlockall call can stop it? > > > > > This may work. And MCL_FUTURE can be toggled, but this is not thread > > safe. > > Just ensure that your one special mmap is done with the other threads > not currently allocating stuff. It's probably a synchronization point > for the whole process anyway. > How can you stop other threads and libraries from calling malloc()? And if it is two special allocations? Or many mmap(big file)/munmap(big file)? This is the same issue as opening file CLOEXEC atomically. Why not prevent other thread from calling fork() instead of adding flags to bunch of system calls.
-- Gleb.
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