Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262574AbVCPNYh (ORCPT ); Wed, 16 Mar 2005 08:24:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262581AbVCPNXA (ORCPT ); Wed, 16 Mar 2005 08:23:00 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:32665 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S262580AbVCPNWH (ORCPT ); Wed, 16 Mar 2005 08:22:07 -0500 Date: Wed, 16 Mar 2005 14:21:52 +0100 From: Pavel Machek To: kernel list , "Rafael J. Wysocki" , rusty@rustcorp.com.au Subject: CPU hotplug on i386 Message-ID: <20050316132151.GA2227@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2977 Lines: 114 Hi! I tried to solve long-standing uglyness in swsusp cmp code by calling cpu hotplug... only to find out that CONFIG_CPU_HOTPLUG is not available on i386. Is there way to enable CPU_HOTPLUG on i386? Pavel --- clean/kernel/power/smp.c 2004-08-15 19:15:06.000000000 +0200 +++ linux/kernel/power/smp.c 2005-03-16 14:16:00.000000000 +0100 @@ -16,70 +16,39 @@ #include #include -static atomic_t cpu_counter, freeze; - - -static void smp_pause(void * data) -{ - struct saved_context ctxt; - __save_processor_state(&ctxt); - printk("Sleeping in:\n"); - dump_stack(); - atomic_inc(&cpu_counter); - while (atomic_read(&freeze)) { - /* FIXME: restore takes place at random piece inside this. - This should probably be written in assembly, and - preserve general-purpose registers, too - - What about stack? We may need to move to new stack here. - - This should better be ran with interrupts disabled. - */ - cpu_relax(); - barrier(); - } - atomic_dec(&cpu_counter); - __restore_processor_state(&ctxt); -} - -cpumask_t oldmask; +cpumask_t frozen_cpus; void disable_nonboot_cpus(void) { - printk("Freezing CPUs (at %d)", smp_processor_id()); - oldmask = current->cpus_allowed; - set_cpus_allowed(current, cpumask_of_cpu(0)); - current->state = TASK_INTERRUPTIBLE; - schedule_timeout(HZ); - printk("..."); - BUG_ON(smp_processor_id() != 0); - - /* FIXME: for this to work, all the CPUs must be running - * "idle" thread (or we deadlock). Is that guaranteed? */ - - atomic_set(&cpu_counter, 0); - atomic_set(&freeze, 1); - smp_call_function(smp_pause, NULL, 0, 0); - while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) { - cpu_relax(); - barrier(); + int cpu, error; + cpus_clear(frozen_cpus); + printk("Freezing cpus...\n"); + for_each_online_cpu(cpu) { + if (!cpu) + continue; + cpu_set(cpu, frozen_cpus); + error = cpu_down(cpu); + if (!error) + continue; + printk("Error taking cpu %d down: %d\n", cpu, error); + panic("Too many cpus"); } - printk("ok\n"); + BUG_ON(smp_processor_id() != 0); } void enable_nonboot_cpus(void) { - printk("Restarting CPUs"); - atomic_set(&freeze, 0); - while (atomic_read(&cpu_counter)) { - cpu_relax(); - barrier(); + int cpu, error; + printk("Thawing cpus...\n"); + for_each_cpu_mask(cpu, frozen_cpus) { + if (!cpu) + continue; + error = cpu_up(cpu); + if (!error) + continue; + printk("Error taking cpu %d up: %d\n", cpu, error); + panic("Not enough cpus"); } - printk("..."); - set_cpus_allowed(current, oldmask); - schedule(); - printk("ok\n"); - } -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/