From f8729e8531cd92e892dd85a3d10669834ad0b23c Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Mon, 25 May 2009 20:25:49 +0000 Subject: [PATCH] powerpc: Convert RTAS event scan from kernel thread to workqueue RTAS event scan has to run across all cpus. Right now we use a kernel thread and set_cpus_allowed but in doing so we wake up the previous cpu unnecessarily. Some ftrace output shows this: previous cpu (2): [002] 7.022331: sched_switch: task swapper:0 [140] ==> rtasd:194 [120] [002] 7.022338: sched_switch: task rtasd:194 [120] ==> migration/2:9 [0] [002] 7.022344: sched_switch: task migration/2:9 [0] ==> swapper:0 [140] next cpu (3): [003] 7.022345: sched_switch: task swapper:0 [140] ==> rtasd:194 [120] [003] 7.022371: sched_switch: task rtasd:194 [120] ==> swapper:0 [140] We can use schedule_delayed_work_on and avoid the unnecessary wakeup. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pseries/rtasd.c | 72 +++++++++++++------------- 1 file changed, 36 insertions(+), 36 deletions(-) diff --git a/arch/powerpc/platforms/pseries/rtasd.c b/arch/powerpc/platforms/pseries/rtasd.c index afad9f5ac0ac..b3cbac855924 100644 --- a/arch/powerpc/platforms/pseries/rtasd.c +++ b/arch/powerpc/platforms/pseries/rtasd.c @@ -19,7 +19,7 @@ #include #include #include -#include +#include #include #include @@ -387,36 +387,51 @@ static void do_event_scan(void) } while(error == 0); } -static void do_event_scan_all_cpus(long delay) +static void rtas_event_scan(struct work_struct *w); +DECLARE_DELAYED_WORK(event_scan_work, rtas_event_scan); + +/* + * Delay should be at least one second since some machines have problems if + * we call event-scan too quickly. + */ +static unsigned long event_scan_delay = 1*HZ; +static int first_pass = 1; + +static void rtas_event_scan(struct work_struct *w) { - int cpu; + unsigned int cpu; + + do_event_scan(); get_online_cpus(); - cpu = first_cpu(cpu_online_map); - for (;;) { - set_cpus_allowed(current, cpumask_of_cpu(cpu)); - do_event_scan(); - set_cpus_allowed(current, CPU_MASK_ALL); - /* Drop hotplug lock, and sleep for the specified delay */ - put_online_cpus(); - msleep_interruptible(delay); - get_online_cpus(); + cpu = next_cpu(smp_processor_id(), cpu_online_map); + if (cpu == NR_CPUS) { + cpu = first_cpu(cpu_online_map); - cpu = next_cpu(cpu, cpu_online_map); - if (cpu == NR_CPUS) - break; + if (first_pass) { + first_pass = 0; + event_scan_delay = 30*HZ/rtas_event_scan_rate; + + if (surveillance_timeout != -1) { + pr_debug("rtasd: enabling surveillance\n"); + enable_surveillance(surveillance_timeout); + pr_debug("rtasd: surveillance enabled\n"); + } + } } + + schedule_delayed_work_on(cpu, &event_scan_work, + __round_jiffies_relative(event_scan_delay, cpu)); + put_online_cpus(); } -static int rtasd(void *unused) +static void start_event_scan(void) { unsigned int err_type; int rc; - daemonize("rtasd"); - printk(KERN_DEBUG "RTAS daemon started\n"); pr_debug("rtasd: will sleep for %d milliseconds\n", (30000 / rtas_event_scan_rate)); @@ -434,22 +449,8 @@ static int rtasd(void *unused) } } - /* First pass. */ - do_event_scan_all_cpus(1000); - - if (surveillance_timeout != -1) { - pr_debug("rtasd: enabling surveillance\n"); - enable_surveillance(surveillance_timeout); - pr_debug("rtasd: surveillance enabled\n"); - } - - /* Delay should be at least one second since some - * machines have problems if we call event-scan too - * quickly. */ - for (;;) - do_event_scan_all_cpus(30000/rtas_event_scan_rate); - - return -EINVAL; + schedule_delayed_work_on(first_cpu(cpu_online_map), &event_scan_work, + event_scan_delay); } static int __init rtas_init(void) @@ -487,8 +488,7 @@ static int __init rtas_init(void) if (!entry) printk(KERN_ERR "Failed to create error_log proc entry\n"); - if (kernel_thread(rtasd, NULL, CLONE_FS) < 0) - printk(KERN_ERR "Failed to start RTAS daemon\n"); + start_event_scan(); return 0; }