>>>>> "DS" == Dan Sugalski <[EMAIL PROTECTED]> writes:
>> obviously gets called for memalign - at least for this arena size)
>> does clear the memory. We need some tests, from which size memory is
>> cleard for malloc and memalign.
>> I tossed the memset for now and saved ~450.000 L2-misses or ~0.2 s.
DS> While I didn't see any memsets in smallobject.c, I'm really, *really*
DS> uncomfortable counting on implied behavior. There's no reason that
DS> mmap has to return zeroed memory, and none of the man pages I have
DS> claim that it does. While it *probably* does, it certainly doesn't
DS> have to, and I'd definitely not count that it does, nor that it's
DS> actually called implicitly. I've been burned by stuff like that before.
you can mmap chunks from /dev/zero and get the behavior you want. it
shouldn't do any L1 stuff until you reference the actual pages and then
they will be zero filled for you on demand. i also don't recall mmap
ever guaranteeing any level of cleanliness.
solaris says this about /dev/zero:
Mapping a zero special file creates a zero-initialized
unnamed memory object of a length equal to the length of the
mapping and rounded up to the nearest page size as returned
by sysconf.
linux says nothing about mmap on /dev/zero in either man page.
uri
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