This is the mail archive of the
mailing list for the systemtap project.
Re: DTrace for Linux
Martin Hunt <firstname.lastname@example.org> writes:
> OK, now this is much different than what Sun got. There is certainly no
> munmap() problem here. Without detail about Sun's emulation environment
> and what version of linux they are running, I cannot even guess what the
> problem is. Maybe one clue is this odd comment "[...]what I've heard my
If I understand BrandZ from the link above correctly it is essentially
running Linux user space on a Solaris kernel.
When munmap is a problem for them and it isn't on native Linux
it just means munmap is much slower on Solaris than on real Linux.
Now that they know they can hopefully do something about this.
However he makes a point that munmap flushes TLBs and scales
with number of CPUs. So it's possible that he ran it on a bigger
system than you and it cost more CPU time because of that.
But I don't quite buy this argument for top because top
is single threaded and Linux will never do remote TLB flushes
for a single threaded process.
It should only make a difference for multithreaded programs where
multiple threads sharing the same VM run on different CPUs.
Perhaps Solaris isn't that clever in avoiding TLB flushes(?) although
it is hard to imagine this.