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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>, Zachary Amsden <zach@vmware.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Ian Campbell <ian.campbell@citrix.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	linux-kernel@vger.kernel.org,
	Ravikiran Thirumalai <kiran@scalemp.com>,
	Xen-devel <xen-devel@lists.xensource.com>
Subject: Re: [PATCH 5 of 7] x86/paravirt: add register-saving thunks to reduce caller register pressure
Date: Fri, 06 Feb 2009 08:37:21 -0800	[thread overview]
Message-ID: <498C6741.8000605@goop.org> (raw)
In-Reply-To: <87fxisvxb9.fsf@basil.nowhere.org>

Andi Kleen wrote:
> I had something like this (but not as generic) for the old pre
> unification semaphores on x86-64 too. I think it's a generally useful
> facility for lots of things (in fact I've been asking gcc developers
> for providing this in a general way for some time).
>   

What other users do you have in mind?

> So I would suggest to move the necessary macros to do that outside
> paravirt.h into a separate include so that it can be used independently
> and not call it PV_*.

That wouldn't be too hard to do, but I don't think its something we 
should do lightly.  There are quite a few pitfalls, and the bugs can get 
pretty obscure.  It would also mean bringing out a lot of the PV_CALL 
machinery, and I'm not sure we really want to give that too much 
exposure in the light of day.

    J


WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Zachary Amsden <zach@vmware.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Ian Campbell <ian.campbell@citrix.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	linux-kernel@vger.kernel.org,
	Ravikiran Thirumalai <kiran@scalemp.com>,
	Xen-devel <xen-devel@lists.xensource.com>,
	Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 5 of 7] x86/paravirt: add register-saving thunks to reduce caller register pressure
Date: Fri, 06 Feb 2009 08:37:21 -0800	[thread overview]
Message-ID: <498C6741.8000605@goop.org> (raw)
In-Reply-To: <87fxisvxb9.fsf@basil.nowhere.org>

Andi Kleen wrote:
> I had something like this (but not as generic) for the old pre
> unification semaphores on x86-64 too. I think it's a generally useful
> facility for lots of things (in fact I've been asking gcc developers
> for providing this in a general way for some time).
>   

What other users do you have in mind?

> So I would suggest to move the necessary macros to do that outside
> paravirt.h into a separate include so that it can be used independently
> and not call it PV_*.

That wouldn't be too hard to do, but I don't think its something we 
should do lightly.  There are quite a few pitfalls, and the bugs can get 
pretty obscure.  It would also mean bringing out a lot of the PV_CALL 
machinery, and I'm not sure we really want to give that too much 
exposure in the light of day.

    J

  reply	other threads:[~2009-02-06 16:37 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-28 22:35 [PATCH 0 of 7] x86/paravirt: optimise pvop calls and register use Jeremy Fitzhardinge
2009-01-28 22:35 ` Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 1 of 7] xen: move remaining mmu-related stuff into mmu.c Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 2 of 7] x86/pvops: add a paravirt_ident functions to allow special patching Jeremy Fitzhardinge
2009-01-29  8:05   ` Rusty Russell
2009-01-29  9:26     ` Jeremy Fitzhardinge
2009-01-29  9:26       ` Jeremy Fitzhardinge
2009-01-29 10:46     ` Jeremy Fitzhardinge
2009-01-29 10:46       ` Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 3 of 7] x86: fix paravirt clobber in entry_64.S Jeremy Fitzhardinge
2009-01-29  8:39   ` Rusty Russell
2009-01-29  9:28     ` Jeremy Fitzhardinge
2009-01-29  9:28       ` Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 4 of 7] x86/paravirt: selectively save/restore regs around pvops calls Jeremy Fitzhardinge
2009-01-29  8:47   ` Rusty Russell
2009-01-29  9:30     ` Jeremy Fitzhardinge
2009-01-29  9:30       ` Jeremy Fitzhardinge
2009-01-30  0:27       ` Rusty Russell
2009-01-28 22:35 ` [PATCH 5 of 7] x86/paravirt: add register-saving thunks to reduce caller register pressure Jeremy Fitzhardinge
2009-01-28 22:35   ` Jeremy Fitzhardinge
2009-02-06  7:28   ` Andi Kleen
2009-02-06 16:37     ` Jeremy Fitzhardinge [this message]
2009-02-06 16:37       ` Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 6 of 7] x86/paravirt: implement PVOP_CALL macros for callee-save functions Jeremy Fitzhardinge
2009-01-28 22:35 ` [PATCH 7 of 7] x86/paravirt: use callee-saved convention for pte_val/make_pte/etc Jeremy Fitzhardinge
2009-01-29  7:14 ` [PATCH 0 of 7] x86/paravirt: optimise pvop calls and register use H. Peter Anvin
2009-01-29  9:51   ` Jeremy Fitzhardinge
2009-01-29  9:51     ` Jeremy Fitzhardinge
2009-01-31  5:04     ` H. Peter Anvin
2009-01-31  7:16       ` Jeremy Fitzhardinge
2009-01-31 22:43         ` H. Peter Anvin
2009-01-31  7:17       ` [PATCH 1/2] x86/paravirt: don't restore second return reg Jeremy Fitzhardinge
2009-01-31  7:17         ` Jeremy Fitzhardinge
2009-01-31  7:18       ` [PATCH 2/2] x86/vmi: fix interrupt enable/disable/save/restore calling convention Jeremy Fitzhardinge
2009-01-31  7:18         ` Jeremy Fitzhardinge
2009-01-31 16:12       ` [PATCH 0 of 7] x86/paravirt: optimise pvop calls and register use Ingo Molnar
2009-01-31 16:12         ` Ingo Molnar
2009-01-31 17:00         ` Jeremy Fitzhardinge
2009-01-31 17:00           ` Jeremy Fitzhardinge
2009-02-04  2:10         ` Ingo Molnar
2009-02-04  2:10           ` Ingo Molnar
2009-02-04  2:16           ` Jeremy Fitzhardinge
2009-02-04  2:16             ` Jeremy Fitzhardinge
2009-02-04 14:26             ` Ingo Molnar
2009-02-04 14:26               ` Ingo Molnar
2009-02-04 17:06               ` Ingo Molnar

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