Messages in this thread | | | Date | Wed, 16 Oct 2002 04:07:54 -0400 | From | Jakub Jelinek <> | Subject | Re: [patch] mmap-speedup-2.5.42-C3 |
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On Wed, Oct 16, 2002 at 10:03:52AM +0200, Ingo Molnar wrote: > > On 15 Oct 2002, Andi Kleen wrote: > > > When you oprofile KDE startup you notice that a lot of time is spent in > > get_unmapped_area too. The reason is that every KDE process links with > > 10-20 libraries and ends up with a 40-50 entry /proc/<pid>/maps. > > actually, library mappings alone should not cause a slowdown, since we > start the search at MAP_UNMAPPED_BASE and most library mappings are below > 1GB. But if those libraries use mmap()-ed anonymous RAM that has different > protections then the anonymous areas do not get merged and the scanning > overhead goes up.
Libraries mapped by dynamic linker are mapped without MAP_FIXED and unless you use prelinking, with 0 virtual address, ie. they all end up above 1GB. And 99% of libraries uses different protections, for the read-only and read-write segment.
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