Re: [PATCH] Native POSIX Thread Library(NPTL) ARM SupportingPatches(1/3)

[Dan Kegel <dank kegel com>]

> > I wonder what the performance impact is of having a system call in
> > THREAD_SELF.  If it turns out to be too great, it may be possible to
> > reduce the overhead by adding some more support to the kernel.  What
> > I've been thinking of is a way for applications to supply a pointer to
> > the kernel (via a new system call), and have it store the 
> > current thread
> > ID at that address during context switch.  That way, retrieving the
> > thread descriptor would be just a regular memory access.

This reminds me of vsyscalls.  Can someone in the know compare and
contrast the current proposal and vsyscalls?
Thanks!

- Dan

p.s. Here's a recent message from around the time they switched
the vsyscall page from something created specially by the kernel
to a tiny ELF image:
http://marc.theaimsgroup.com/?l=linux-kernel&m=105123323202704&w=2

--
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045