From: Andi Kleen <ak@muc.de>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
virtualization <virtualization@lists.osdl.org>,
Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCH 5/7] Use %gs for per-cpu sections in kernel
Date: 23 Sep 2006 10:17:55 +0200
Date: Sat, 23 Sep 2006 10:17:55 +0200 [thread overview]
Message-ID: <20060923081755.GB10534@muc.de> (raw)
In-Reply-To: <1158987075.26261.79.camel@localhost.localdomain>
> Mainly that it makes more sense to use the existing per-cpu concept than
> introduce another kind of per-cpu var within a special structure, but
> it's also more efficient (see other post). Hopefully it will spark
What post exactly? AFAIK it is the same code for common code.
The advantage of the PDA split is that the important variables which are
in the PDA can be accessed with a single reference, while generic portable
per CPU data is the same as it was before. With your scheme even
the PDA accesses are at least two instructions, right? (I don't
think gcc/ld can resolve the per cpu section offset into a constant,
so it has to load them into a register first)
> interest in making dynamic-percpu pointers use the same offset scheme,
> now x86 will experience the benefits.
>
> And we might even get a third user of local_t!
I'm not holding my breath. I guess it was a nice idea before preemption
became popular ...
-Andi
next prev parent reply other threads:[~2006-09-23 8:17 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-22 11:51 [PATCH 0/7] Using %gs for per-cpu areas on x86 Rusty Russell
2006-09-22 11:53 ` [PATCH 1/7] Use per-cpu GDT tables from early in boot Rusty Russell
2006-09-22 11:55 ` [PATCH 2/7] Rusty Russell
2006-09-22 11:56 ` [PATCH 3/7] Update sys_vm86 to cope with changed pt_regs and %gs usage Rusty Russell
2006-09-22 11:58 ` [PATCH 4/7] Fix places where using %gs changes the usermode ABI Rusty Russell
2006-09-22 11:59 ` [PATCH 5/7] Use %gs for per-cpu sections in kernel Rusty Russell
2006-09-22 12:00 ` [PATCH 6/7] (Optional) implement smp_processor_id() as a per-cpu var Rusty Russell
2006-09-22 12:01 ` [PATCH 7/7] (Optional) implement current " Rusty Russell
2006-09-25 5:29 ` Rusty Russell
2006-09-25 5:27 ` [PATCH 6/7] (Optional) implement smp_processor_id() " Rusty Russell
2006-09-22 12:32 ` [PATCH 5/7] Use %gs for per-cpu sections in kernel Andi Kleen
2006-09-22 22:43 ` Jeremy Fitzhardinge
2006-09-22 23:52 ` Andi Kleen
2006-09-23 4:51 ` Rusty Russell
2006-09-23 8:17 ` Andi Kleen [this message]
2006-09-23 8:55 ` Rusty Russell
2006-09-22 22:39 ` Jeremy Fitzhardinge
2006-09-23 4:31 ` Rusty Russell
2006-09-25 1:03 ` Jeremy Fitzhardinge
2006-09-25 1:16 ` Rusty Russell
2006-09-25 1:36 ` Jeremy Fitzhardinge
2006-09-25 2:51 ` Rusty Russell
2006-09-25 5:25 ` Jeremy Fitzhardinge
2006-09-25 6:03 ` Rusty Russell
2006-09-25 6:25 ` Jeremy Fitzhardinge
2006-09-25 23:33 ` Rusty Russell
2006-09-23 8:13 ` Andi Kleen
2006-09-25 1:07 ` Jeremy Fitzhardinge
2006-09-25 1:20 ` Rusty Russell
2006-09-25 5:26 ` Rusty Russell
2006-09-22 22:24 ` [PATCH 2/7] Jeremy Fitzhardinge
2006-09-23 4:36 ` Rusty Russell
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