From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ken Chen" Date: Tue, 07 Aug 2007 21:26:16 +0000 Subject: Re: [PATCH] disable irq's and check need_resched before safe_halt Message-Id: List-Id: References: <20070807134932.GA30447@sgi.com> In-Reply-To: <20070807134932.GA30447@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On 8/7/07, Luck, Tony wrote: > This looks like it re-introduces code that Ken Chen backed out > about two years ago. Here's Ken's commit that explains what > broke last time we made the idle loop look like this. Now > that code was wider ranging ... messing with TIF bits too, > so maybe this is different this time? Yeah, I think the TIF flag was the key in fixing the resched IPI notification. The change in default_idle() is an optimization. I'm horrified to see the same code coming back: doing interrupt enable/disable in the most inner while loop. Disable interrupt is just crude, but I suppose that's the only way to resolve the race condition? Looking at other arch like x86_64, it is also doing the same thing. - Ken