Messages in this thread | | | Date | Fri, 06 Apr 2007 12:28:19 +1000 | From | Nick Piggin <> | Subject | Re: missing madvise functionality |
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Ulrich Drepper wrote: > In case somebody wants to play around with Rik patch or another > madvise-based patch, I have x86-64 glibc binaries which can use it: > > http://people.redhat.com/drepper/rpms > > These are based on the latest Fedora rawhide version. They should work > on older systems, too, but you screw up your updates. Use them only if > you know what you do. > > By default madvise(MADV_DONTNEED) is used. With the environment variable
Cool. According to my thinking, madvise(MADV_DONTNEED) even in today's kernels using down_write(mmap_sem) for MADV_DONTNEED is better than mmap/mprotect, which have more fundamental locking requirements, more overhead and no benefits (except debugging, I suppose).
MADV_DONTNEED is twice as fast in single threaded performance, and an order of magnitude faster for multiple threads, when MADV_DONTNEED only takes mmap_sem for read.
Do you plan to include this change in general glibc releases? Maybe it will make google malloc obsolete? ;) (I don't suppose you'd be able to get any tests done, Andrew?)
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