From: Andi Kleen <ak@suse.de>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>,
davidm@hpl.hp.com, linux-kernel@vger.kernel.org, rth@twiddle.net
Subject: Re: [PATCH] 2.5.1-pre5: per-cpu areas
Date: Tue, 19 Mar 2002 01:15:34 +0100 [thread overview]
Message-ID: <20020319011534.A32751@wotan.suse.de> (raw)
In-Reply-To: <20020318083511.A19810@wotan.suse.de> <E16n74r-00024V-00@wagner.rustcorp.com.au>
On Tue, Mar 19, 2002 at 11:02:09AM +1100, Rusty Russell wrote:
> In message <20020318083511.A19810@wotan.suse.de> you write:
> > On Sun, Mar 17, 2002 at 06:17:32PM +1100, Rusty Russell wrote:
> > > On Fri, 15 Mar 2002 10:13:09 +0100
> > > Andi Kleen <ak@suse.de> wrote:
> > >
> > > > On Fri, Mar 15, 2002 at 03:07:27PM +1100, Rusty Russell wrote:
> > > > > They must return an lvalue, otherwise they're useless for 50% of cases
> > > > > (ie. assignment). x86_64 can still use its own mechanism for
> > > > > arch-specific per-cpu data, of course.
> > > >
> > > > Assignment should use an own macro (set_this_cpu()) or use per_cpu().
> > >
> > > So, we'd have "get_this_cpu(x)" and "set_this_cpu(x, y)". So far, so good.
> > >
> > > struct myinfo
> > > {
> > > int x;
> > > int y;
> > > };
> > >
> > > static struct myinfo mystuff __per_cpu_data;
> > >
> > > Now how do we set mystuff.x on this CPU?
> >
> > set_this_cpu(mystuff.x, y) could be eventually supported properly, it just
> > needs compiler work (and before that can use address calculation & reference)
>
> I think the effort would be better spent on teaching the compiler
> about these special variables, and how to do efficient assignments on
> them.
That would be the idea. gcc would learn how to use the %gs segment prefix
(similar to the equivalent feature in Windows compilers). The only
drawback is that it still cannot easily load the address except if you
define some silly convention (like a pointer to the segment base being
always stored at the segment base address)
But it is a lot of work to teach gcc about the multiple address spaces...
-Andi
next prev parent reply other threads:[~2002-03-19 0:15 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <15504.7958.677592.908691@napali.hpl.hp.com.suse.lists.linux.kernel>
[not found] ` <E16lMzi-0002bb-00@wagner.rustcorp.com.au.suse.lists.linux.kernel>
2002-03-14 8:39 ` [PATCH] 2.5.1-pre5: per-cpu areas Andi Kleen
2002-03-14 11:09 ` Rusty Russell
2002-03-14 11:14 ` Andi Kleen
2002-03-14 19:48 ` H. Peter Anvin
2002-03-14 18:04 ` David Mosberger
2002-03-14 18:51 ` Andi Kleen
2002-03-15 4:07 ` Rusty Russell
2002-03-15 9:13 ` Andi Kleen
2002-03-17 7:17 ` Rusty Russell
2002-03-18 7:35 ` Andi Kleen
2002-03-19 0:02 ` Rusty Russell
2002-03-19 0:08 ` J.A. Magallon
2002-03-19 0:15 ` Andi Kleen [this message]
2002-03-19 17:05 ` Richard Henderson
2002-03-15 4:19 ` David Mosberger
2002-03-15 5:52 ` Rusty Russell
[not found] <15504.7958.677592.908691@napali.hpl.hp.com>
2002-03-14 4:37 ` Rusty Russell
2002-03-14 5:05 ` Jeff Garzik
2002-03-14 11:14 ` Rusty Russell
2002-03-14 11:26 ` Jeff Garzik
2002-03-14 12:16 ` Rusty Russell
2002-03-14 12:25 ` Jeff Garzik
2002-03-15 1:00 ` Richard Henderson
2002-03-14 9:37 ` Richard Henderson
2002-03-14 18:06 ` David Mosberger
2001-12-05 22:09 Rusty Russell
2001-12-06 7:21 ` Keith Owens
2001-12-06 8:07 ` David S. Miller
2001-12-06 9:18 ` Chris Wedgwood
2001-12-07 15:03 ` Pavel Machek
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