Re: Android performance drop moving from LuaJIT-2.0.1 -> LuaJIT-2.0.2 ?
- From: Mike Pall <mike-1309@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Fri, 6 Sep 2013 00:16:00 +0200
Kriss@xxxxxxxx wrote:
> As far as I can tell the problem is just that android is not letting me
> allocate any memory close enough to the location I want, when the range was
> double it works first time.
I think it's just a coincidence that it worked. It looks like
regular memory allocations and the space for shared libraries are
drawn from the same linear address pool. Due to the high virtual
memory pressure in your app, all gaps around the shared library
will eventually be filled.
An easy way to work around this would be prelinking the shared
library to a specific address far away from everything else. Alas,
Android deprecated prelinking with 4.x due to security concerns
and finally disabled it in 4.2.
Playing with the ELF virtual load address doesn't work, because
Bionic doesn't permit a non-zero image base address for shared
libraries.
The only workaround I can think of (without rewriting the dynamic
linker) would be to mmap() a huge block of virtual memory with
PROT_NONE, then load the LuaJIT shared library and munmap() the
block right after that. That should put the shared library out of
reach of the memory allocator.
--Mike
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