From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Mon, 21 Jan 2002 20:23:08 +0000 Subject: Re: [Linux-ia64] Help with Ingo scheduler on IA64 Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Mon, 21 Jan 2002 23:11:49 +0100 (CET), Ingo Molnar said: Ingo> On Mon, 21 Jan 2002, David Mosberger wrote: Ingo> we call context_switch() with irqs disabled. The ia64 version Ingo> of switch_to() should not re-enable IRQs or it will deadlock. >> The existing switch_to() enables interrupts if the new task's >> stack is on a different (kernel-) page. Ingo> oh, i see. Why were irqs enabled explicitly? The old scheduler Ingo> called switch_to() with irqs enabled, all the time. Eh, that's not true. The old scheduler did spin_unlock_irq() before calling switch_to(). If your scheduler requires irq's to be disabled during context switch, it's going to have bigger interrupt response latency. That's a disadvantage. --david