On Wed, 2 Jan 2008, Gary Stanley wrote:
At 06:00 AM 1/2/2008, Kris Kennaway wrote:
Per later discussion you will also need to either comment out the syscalls
that are (might be) being cached by glibc to artificially inflate its
reported rate, or verify that it is not doing so.
IIRC linux uses vsyscalls on x86_64, and calling things like gettimeofday()
isn't as expensive as it normally should be.. vsyscalls are similar to
darwins' commpage.
How does it implement gettimeofday()'s 1us precision using direct access?
I see one way: put the time and other volatiles on an unmapped page, and
update the time in the trap handler. With a lot of work, this should
be only slightly slower than the gettimeofday() syscall.
Bruce
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