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From: Rusty Russell <rusty@rustcorp.com.au>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	Andi Kleen <ak@muc.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Chuck Ebbert <cebbert@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [patch 5/8] Immediate Values - x86 Optimization (simplified)
Date: Tue, 20 Nov 2007 10:06:34 +1100	[thread overview]
Message-ID: <200711201006.34954.rusty@rustcorp.com.au> (raw)
In-Reply-To: <20071119142803.GA19301@Krystal>

On Tuesday 20 November 2007 01:28:03 Mathieu Desnoyers wrote:
> * Rusty Russell (rusty@rustcorp.com.au) wrote:
> > I think it would be easier to just fast-path the num_online_cpus == 1
> > case, even if you want to keep this "update_early" interface.
>
> Nope, that could lead to problems. I call core_immediate_update()
> _very_ early, before boot_cpu_init() is called.

Ah, I see the problem.  It would in fact be clearer for us to move 
boot_cpu_init() up to just after smp_setup_processor_id() in start_kernel 
anyway, not just for this code, but in general.

> Therefore, 
> cpu_online_map is not set yet. I am not sure the benefit of using
> num_online_cpus outweights the added fragility wrt other boot process
> initializations.

I think it's still a win, though worth a comment that we always go via the 
non-IPI path for the early boot case.

Cheers,
Rusty.

  reply	other threads:[~2007-11-19 23:06 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-13 18:58 [patch 0/8] Immediate Values (now with merged x86 support) Mathieu Desnoyers
2007-11-13 18:58 ` [patch 1/8] Immediate Values - Architecture Independent Code Mathieu Desnoyers
2007-11-13 18:58 ` [patch 2/8] Immediate Values - Kconfig menu in EMBEDDED Mathieu Desnoyers
2007-11-13 18:58 ` [patch 3/8] Immediate Values - Move Kprobes x86 restore_interrupt to kdebug.h Mathieu Desnoyers
2007-11-13 18:58 ` [patch 4/8] Add asm-compat.h to x86 Mathieu Desnoyers
2007-11-13 19:05   ` H. Peter Anvin
2007-11-13 20:37     ` [patch 4/8] Add asm-compat.h to x86 -> use new asm.h instead Mathieu Desnoyers
2007-11-13 18:58 ` [patch 5/8] Immediate Values - x86 Optimization Mathieu Desnoyers
2007-11-13 19:07   ` H. Peter Anvin
2007-11-13 19:24     ` Mathieu Desnoyers
2007-11-13 19:36       ` H. Peter Anvin
2007-11-13 19:45         ` Mathieu Desnoyers
2007-11-13 19:56           ` H. Peter Anvin
2007-11-13 20:40             ` [patch 5/8] Immediate Values - x86 Optimization (update) Mathieu Desnoyers
2007-11-13 21:26               ` H. Peter Anvin
2007-11-13 22:02                 ` Mathieu Desnoyers
2007-11-13 22:35                   ` H. Peter Anvin
2007-11-14  0:34                     ` Mathieu Desnoyers
2007-11-14  1:02                       ` H. Peter Anvin
2007-11-14  1:44                         ` [patch 5/8] Immediate Values - x86 Optimization (update 2) Mathieu Desnoyers
2007-11-14  2:58                           ` H. Peter Anvin
2007-11-14 14:16                             ` Mathieu Desnoyers
2007-11-14 18:52                             ` [PATCH] Immediate Values x86 Optimization Declare Discarded Instruction Mathieu Desnoyers
2007-11-14 19:00                               ` H. Peter Anvin
2007-11-14 19:16                                 ` [PATCH] Add __discard section to x86 Mathieu Desnoyers
2007-11-14 19:33                                   ` H. Peter Anvin
2007-11-15  3:08   ` [patch 5/8] Immediate Values - x86 Optimization Rusty Russell
2007-11-15  4:06     ` Mathieu Desnoyers
2007-11-15  4:45       ` Rusty Russell
2007-11-15  5:37         ` Mathieu Desnoyers
2007-11-15 11:06           ` Rusty Russell
2007-11-16 14:03             ` [patch 5/8] Immediate Values - x86 Optimization (simplified) Mathieu Desnoyers
2007-11-18 23:11               ` Rusty Russell
2007-11-19 14:28                 ` Mathieu Desnoyers
2007-11-19 23:06                   ` Rusty Russell [this message]
2007-11-20 17:02                     ` Mathieu Desnoyers
2007-11-19 19:15                 ` Mathieu Desnoyers
2007-11-13 18:58 ` [patch 6/8] Immediate Values - Powerpc Optimization Mathieu Desnoyers
2007-11-13 18:58 ` [patch 7/8] Immediate Values - Documentation Mathieu Desnoyers
2007-11-13 18:58 ` [patch 8/8] Scheduler Profiling - Use Immediate Values Mathieu Desnoyers

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