Re: [PATCH 00/05] robust per_cpu allocation for modules

From: Paul Mackerras <paulus_at_samba.org>
Date: 2006-04-16 17:02:19
Steven Rostedt writes:

> So now I'm asking for advice on some ideas that can be a work around to
> keep the robustness and speed.

Ideally, what I'd like to do on powerpc is to dedicate one register to
storing a per-cpu base address or offset, and be able to resolve the
offset at link time, so that per-cpu variable accesses just become a
register + offset memory access.  (For modules, "link time" would be
module load time.)

We *might* be able to use some of the infrastructure that was put into
gcc and binutils to support TLS (thread local storage) to achieve
this.  (See http://people.redhat.com/drepper/tls.pdf for some of the
details of that.)

Also, I've added Rusty Russell to the cc list, since he designed the
per-cpu variable stuff in the first place, and would be able to
explain the trade-offs that led to the PERCPU_ENOUGH_ROOM thing.  (I
think you're discovering them as you go, though. :)

Paul.
-
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Received on Sun Apr 16 17:03:03 2006

This archive was generated by hypermail 2.1.8 : 2006-04-16 17:03:12 EST