From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Mon, 21 Jan 2002 20:10:56 +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 21:32:28 +0100 (CET), Ingo Molnar said: Ingo> On Mon, 21 Jan 2002, Erich Focht wrote: >> Unfortunately the context switch in Ingo's scheduler happens with >> the runqueue lock held, which can lead to a deadlock eg. if the >> timer interrupt is called inside and sched_tick spinlocks on the >> runqueue lock held by schedule(). On IA64 (HZ24) this probably >> happens much more frequently than on IA32 (HZ0). 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. If the new scheduler guarantees to call switch_to() with irqs disabled, we can simply drop the relevant code. --david