Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936206AbZDJRew (ORCPT ); Fri, 10 Apr 2009 13:34:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757617AbZDJRel (ORCPT ); Fri, 10 Apr 2009 13:34:41 -0400 Received: from relay3.sgi.com ([192.48.156.57]:60581 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1762149AbZDJRej (ORCPT ); Fri, 10 Apr 2009 13:34:39 -0400 Date: Fri, 10 Apr 2009 12:34:37 -0500 From: Dimitri Sivanich To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Ingo Molnar , john stultz , Thomas Gleixner Subject: [PATCH v2] Move calc_load call out from xtime_lock protection Message-ID: <20090410173437.GA23415@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 14947 Lines: 472 The xtime_lock is being held for long periods on larger systems due to an extensive amount of time being spent in calc_load(), specifically here: do_timer->update_times->calc_load->count_active_tasks->nr_active() On a 64 cpu system I've seen this take approximately 55 usec. Presumably it would be worse on larger systems. This causes other cpus to be held off in places such as scheduler_tick->sched_clock_tick waiting for the xtime_lock to be released. >From e3e61df08f615c39d2d6f27918561c84e1439050 Mon Sep 17 00:00:00 2001 From: Dimitri Sivanich Date: Thu, 9 Apr 2009 14:37:28 -0500 Subject: [PATCH] Remove calc_load from xtime_lock protection. --- Made modifications recommended by John Stultz. Refreshed for 2.6.30-rc1. Tested on ia64 and x86. arch/alpha/kernel/time.c | 1 + arch/arm/kernel/time.c | 1 + arch/arm/mach-clps711x/include/mach/time.h | 2 ++ arch/arm/mach-l7200/include/mach/time.h | 2 ++ arch/blackfin/kernel/time.c | 2 ++ arch/cris/arch-v10/kernel/time.c | 2 ++ arch/cris/arch-v32/kernel/time.c | 1 + arch/frv/kernel/time.c | 1 + arch/h8300/kernel/time.c | 1 + arch/ia64/kernel/time.c | 1 + arch/ia64/xen/time.c | 2 ++ arch/m32r/kernel/time.c | 1 + arch/m68k/kernel/time.c | 1 + arch/m68k/sun3/sun3ints.c | 1 + arch/m68knommu/kernel/time.c | 2 ++ arch/mn10300/kernel/time.c | 1 + arch/parisc/kernel/time.c | 1 + arch/sh/kernel/time_32.c | 1 + arch/sh/kernel/time_64.c | 1 + arch/sparc/kernel/pcic.c | 2 ++ arch/sparc/kernel/time_32.c | 1 + arch/xtensa/kernel/time.c | 2 ++ include/linux/timer.h | 5 +++++ kernel/time/tick-common.c | 1 + kernel/time/tick-sched.c | 2 ++ kernel/timer.c | 22 +++++++++++++++------- 26 files changed, 53 insertions(+), 7 deletions(-) diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c index b04e2cb..461fe34 100644 --- a/arch/alpha/kernel/time.c +++ b/arch/alpha/kernel/time.c @@ -137,6 +137,7 @@ irqreturn_t timer_interrupt(int irq, void *dev) } write_sequnlock(&xtime_lock); + calc_load(nticks); #ifndef CONFIG_SMP while (nticks--) diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c index 4cdc4a0..aa96509 100644 --- a/arch/arm/kernel/time.c +++ b/arch/arm/kernel/time.c @@ -339,6 +339,7 @@ void timer_tick(void) write_seqlock(&xtime_lock); do_timer(1); write_sequnlock(&xtime_lock); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif diff --git a/arch/arm/mach-clps711x/include/mach/time.h b/arch/arm/mach-clps711x/include/mach/time.h index 8fe283c..afa3c3b 100644 --- a/arch/arm/mach-clps711x/include/mach/time.h +++ b/arch/arm/mach-clps711x/include/mach/time.h @@ -17,6 +17,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ +#include #include #include @@ -31,6 +32,7 @@ p720t_timer_interrupt(int irq, void *dev_id) struct pt_regs *regs = get_irq_regs(); do_leds(); do_timer(1); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(regs)); #endif diff --git a/arch/arm/mach-l7200/include/mach/time.h b/arch/arm/mach-l7200/include/mach/time.h index 061771c..80df87b 100644 --- a/arch/arm/mach-l7200/include/mach/time.h +++ b/arch/arm/mach-l7200/include/mach/time.h @@ -11,6 +11,7 @@ #ifndef _ASM_ARCH_TIME_H #define _ASM_ARCH_TIME_H +#include #include /* @@ -47,6 +48,7 @@ timer_interrupt(int irq, void *dev_id) { struct pt_regs *regs = get_irq_regs(); do_timer(1); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(regs)); #endif diff --git a/arch/blackfin/kernel/time.c b/arch/blackfin/kernel/time.c index 1bbacfb..b5b55d2 100644 --- a/arch/blackfin/kernel/time.c +++ b/arch/blackfin/kernel/time.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -164,6 +165,7 @@ irqreturn_t timer_interrupt(int irq, void *dummy) } #endif write_sequnlock(&xtime_lock); + calc_load(1); #ifdef CONFIG_IPIPE update_root_process_times(get_irq_regs()); diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c index 2b73c7a..951712a 100644 --- a/arch/cris/arch-v10/kernel/time.c +++ b/arch/cris/arch-v10/kernel/time.c @@ -231,6 +231,8 @@ timer_interrupt(int irq, void *dev_id) /* call the real timer interrupt handler */ do_timer(1); + + calc_load(1); cris_do_profile(regs); /* Save profiling information */ diff --git a/arch/cris/arch-v32/kernel/time.c b/arch/cris/arch-v32/kernel/time.c index 65633d0..2b4bb52 100644 --- a/arch/cris/arch-v32/kernel/time.c +++ b/arch/cris/arch-v32/kernel/time.c @@ -240,6 +240,7 @@ timer_interrupt(int irq, void *dev_id) /* Call the real timer interrupt handler */ do_timer(1); + calc_load(1); /* * If we have an externally synchronized Linux clock, then update * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be diff --git a/arch/frv/kernel/time.c b/arch/frv/kernel/time.c index fb0ce75..3d73275 100644 --- a/arch/frv/kernel/time.c +++ b/arch/frv/kernel/time.c @@ -97,6 +97,7 @@ static irqreturn_t timer_interrupt(int irq, void *dummy) #endif /* CONFIG_HEARTBEAT */ write_sequnlock(&xtime_lock); + calc_load(1); update_process_times(user_mode(get_irq_regs())); diff --git a/arch/h8300/kernel/time.c b/arch/h8300/kernel/time.c index 7f2d6cf..d3a9b6f 100644 --- a/arch/h8300/kernel/time.c +++ b/arch/h8300/kernel/time.c @@ -38,6 +38,7 @@ void h8300_timer_tick(void) write_seqlock(&xtime_lock); do_timer(1); write_sequnlock(&xtime_lock); + calc_load(1); update_process_times(user_mode(get_irq_regs())); } diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index 641c8b6..022786f 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c @@ -201,6 +201,7 @@ timer_interrupt (int irq, void *dev_id) do_timer(1); local_cpu_data->itm_next = new_itm; write_sequnlock(&xtime_lock); + calc_load(1); } else local_cpu_data->itm_next = new_itm; diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c index fb83326..59dcadc 100644 --- a/arch/ia64/xen/time.c +++ b/arch/ia64/xen/time.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -145,6 +146,7 @@ consider_steal_time(unsigned long new_itm) do_timer(stolen + blocked); local_cpu_data->itm_next = delta_itm + new_itm; write_sequnlock(&xtime_lock); + calc_load(stolen + blocked); } else { local_cpu_data->itm_next = delta_itm + new_itm; } diff --git a/arch/m32r/kernel/time.c b/arch/m32r/kernel/time.c index cada3ba..8df1e8a 100644 --- a/arch/m32r/kernel/time.c +++ b/arch/m32r/kernel/time.c @@ -193,6 +193,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id) profile_tick(CPU_PROFILING); #endif do_timer(1); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c index 54d9807..a3b6f80 100644 --- a/arch/m68k/kernel/time.c +++ b/arch/m68k/kernel/time.c @@ -42,6 +42,7 @@ static inline int set_rtc_mmss(unsigned long nowtime) static irqreturn_t timer_interrupt(int irq, void *dummy) { do_timer(1); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif diff --git a/arch/m68k/sun3/sun3ints.c b/arch/m68k/sun3/sun3ints.c index ad90393..55c63be 100644 --- a/arch/m68k/sun3/sun3ints.c +++ b/arch/m68k/sun3/sun3ints.c @@ -67,6 +67,7 @@ static irqreturn_t sun3_int5(int irq, void *dev_id) intersil_clear(); #endif do_timer(1); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c index d182b2f..55dc581 100644 --- a/arch/m68knommu/kernel/time.c +++ b/arch/m68knommu/kernel/time.c @@ -50,6 +50,8 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy) write_sequnlock(&xtime_lock); + calc_load(1); + #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif diff --git a/arch/mn10300/kernel/time.c b/arch/mn10300/kernel/time.c index 395caf0..1d9c2d6 100644 --- a/arch/mn10300/kernel/time.c +++ b/arch/mn10300/kernel/time.c @@ -111,6 +111,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id) /* advance the kernel's time tracking system */ profile_tick(CPU_PROFILING); do_timer(1); + calc_load(1); check_rtc_time(); } diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c index d4dd056..75fcf95 100644 --- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -148,6 +148,7 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id) write_seqlock(&xtime_lock); do_timer(ticks_elapsed); write_sequnlock(&xtime_lock); + calc_load(ticks_elapsed); } return IRQ_HANDLED; diff --git a/arch/sh/kernel/time_32.c b/arch/sh/kernel/time_32.c index c34e1e0..0c712b2 100644 --- a/arch/sh/kernel/time_32.c +++ b/arch/sh/kernel/time_32.c @@ -142,6 +142,7 @@ void handle_timer_tick(void) last_rtc_update = xtime.tv_sec - 600; } write_sequnlock(&xtime_lock); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); diff --git a/arch/sh/kernel/time_64.c b/arch/sh/kernel/time_64.c index 988c77c..db6739f 100644 --- a/arch/sh/kernel/time_64.c +++ b/arch/sh/kernel/time_64.c @@ -256,6 +256,7 @@ static inline void do_timer_interrupt(void) last_rtc_update = xtime.tv_sec - 600; } write_sequnlock(&xtime_lock); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c index 85e7037..4b8ef99 100644 --- a/arch/sparc/kernel/pcic.c +++ b/arch/sparc/kernel/pcic.c @@ -12,6 +12,7 @@ #include #include +#include #include #include #include @@ -707,6 +708,7 @@ static irqreturn_t pcic_timer_handler (int irq, void *h) pcic_clear_clock_irq(); do_timer(1); write_sequnlock(&xtime_lock); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); #endif diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c index 614ac7b..d032145 100644 --- a/arch/sparc/kernel/time_32.c +++ b/arch/sparc/kernel/time_32.c @@ -110,6 +110,7 @@ static irqreturn_t timer_interrupt(int dummy, void *dev_id) last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */ } write_sequnlock(&xtime_lock); + calc_load(1); #ifndef CONFIG_SMP update_process_times(user_mode(get_irq_regs())); diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c index 8848120..9e8cfd9 100644 --- a/arch/xtensa/kernel/time.c +++ b/arch/xtensa/kernel/time.c @@ -13,6 +13,7 @@ */ #include +#include #include #include #include @@ -111,6 +112,7 @@ again: set_linux_timer(next); write_sequnlock(&xtime_lock); + calc_load(1); } /* Allow platform to do something useful (Wdog). */ diff --git a/include/linux/timer.h b/include/linux/timer.h index 6cdb6f3..9060a13 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -183,6 +183,11 @@ extern unsigned long next_timer_interrupt(void); extern unsigned long get_next_timer_interrupt(unsigned long now); /* + * Calculate load averages. + */ +extern void calc_load(unsigned long); + +/* * Timer-statistics info: */ #ifdef CONFIG_TIMER_STATS diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index 21a5ca8..094aab9 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -67,6 +67,7 @@ static void tick_periodic(int cpu) do_timer(1); write_sequnlock(&xtime_lock); + calc_load(1); } update_process_times(user_mode(get_irq_regs())); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index d3f1ef4..fd4f058 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -81,6 +81,8 @@ static void tick_do_update_jiffies64(ktime_t now) tick_next_period = ktime_add(last_jiffies_update, tick_period); } write_sequnlock(&xtime_lock); + if (ticks) + calc_load(ticks); } /* diff --git a/kernel/timer.c b/kernel/timer.c index cffffad..472e9b1 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1136,30 +1136,39 @@ static unsigned long count_active_tasks(void) * Nothing else seems to be standardized: the fractional size etc * all seem to differ on different machines. * - * Requires xtime_lock to access. + * Requires avenrun_lock to write. Readers are not protected. */ unsigned long avenrun[3]; +static DEFINE_SPINLOCK(avenrun_lock); EXPORT_SYMBOL(avenrun); /* * calc_load - given tick count, update the avenrun load estimates. - * This is called while holding a write_lock on xtime_lock. */ -static inline void calc_load(unsigned long ticks) +void calc_load(unsigned long ticks) { unsigned long active_tasks; /* fixed-point */ static int count = LOAD_FREQ; count -= ticks; if (unlikely(count < 0)) { + unsigned long avr_1, avr_5, avr_15; active_tasks = count_active_tasks(); + spin_lock(&avenrun_lock); + avr_1 = avenrun[0]; + avr_5 = avenrun[1]; + avr_15 = avenrun[2]; do { - CALC_LOAD(avenrun[0], EXP_1, active_tasks); - CALC_LOAD(avenrun[1], EXP_5, active_tasks); - CALC_LOAD(avenrun[2], EXP_15, active_tasks); + CALC_LOAD(avr_1, EXP_1, active_tasks); + CALC_LOAD(avr_5, EXP_5, active_tasks); + CALC_LOAD(avr_15, EXP_15, active_tasks); count += LOAD_FREQ; } while (count < 0); + avenrun[0] = avr_1; + avenrun[1] = avr_5; + avenrun[2] = avr_15; + spin_unlock(&avenrun_lock); } } @@ -1193,7 +1202,6 @@ void run_local_timers(void) static inline void update_times(unsigned long ticks) { update_wall_time(); - calc_load(ticks); } /* -- 1.5.4.rc3 -- 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/