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Nick Piggin ff91691bcc [PATCH] sched: avoid div in rebalance_tick 
Avoid expensive integer divide 3 times per CPU per tick.

A userspace test of this loop went from 26ns, down to 19ns on a G5; and
from 123ns down to 28ns on a P3.

(Also avoid a variable bit shift, as suggested by Alan. The effect
of this wasn't noticable on the CPUs I tested with).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:37 -08:00
..
irq [PATCH] kernel: shut up the IRQ mismatch messages 2007-02-12 09:48:28 -08:00
power [PATCH] swsusp: Change pm_ops handling by userland interface 2007-02-11 10:51:20 -08:00
time [PATCH] kernel/time/clocksource.c needs struct task_struct on m68k 2007-02-11 10:51:20 -08:00
.gitignore gitignore: ignore more generated files 2006-01-03 11:35:26 +01:00
acct.c [PATCH] kernel: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:42 -08:00
audit.c [PATCH] Add include/linux/freezer.h and move definitions from sched.h 2006-12-07 08:39:27 -08:00
audit.h [PATCH] audit: AUDIT_PERM support 2006-09-11 13:32:30 -04:00
auditfilter.c [PATCH] audit: fix audit_filter_user_rules() initialization bug 2007-02-11 10:51:34 -08:00
auditsc.c [PATCH] struct path: convert kernel 2006-12-08 08:28:46 -08:00
capability.c [PATCH] pid: replace do/while_each_task_pid with do/while_each_pid_task 2007-02-12 09:48:32 -08:00
compat.c [PATCH] Common compat_sys_sysinfo 2007-02-11 10:51:32 -08:00
configs.c [PATCH] struct seq_operations and struct file_operations constification 2006-12-07 08:39:46 -08:00
cpu.c [PATCH] swsusp: Change code ordering in disk.c 2007-02-11 10:51:19 -08:00
cpuset.c [PATCH] cpuset procfs warning fix 2006-12-30 10:56:43 -08:00
delayacct.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
dma.c [PATCH] struct seq_operations and struct file_operations constification 2006-12-07 08:39:46 -08:00
exec_domain.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
exit.c [PATCH] pid: replace is_orphaned_pgrp with is_current_pgrp_orphaned 2007-02-12 09:48:32 -08:00
extable.c [PATCH] symbol_put_addr() locks kernel 2006-05-15 11:20:55 -07:00
fork.c [PATCH] tty: update the tty layer to work with struct pid 2007-02-12 09:48:32 -08:00
futex.c [PATCH] kernel: change uses of f_{dentry, vfsmnt} to use f_path 2006-12-08 08:28:42 -08:00
futex_compat.c [PATCH] __user annotations: futex 2006-10-10 15:37:22 -07:00
hrtimer.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
itimer.c [PATCH] hrtimers: remove data field 2006-03-26 08:57:03 -08:00
kallsyms.c [PATCH] move kallsyms data to .rodata 2006-12-08 08:28:37 -08:00
Kconfig.hz [PATCH] HZ: 300Hz support 2006-12-07 08:39:36 -08:00
Kconfig.preempt [PATCH] sched: voluntary kernel preemption 2005-06-25 16:24:45 -07:00
kexec.c Merge branch 'release' of master.kernel.org:/pub/scm/linux/kernel/git/aegl/linux-2.6 2006-12-07 15:39:22 -08:00
kfifo.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
kmod.c [PATCH] rename struct namespace to struct mnt_namespace 2006-12-08 08:28:51 -08:00
kprobes.c [PATCH] kprobes: replace magic numbers with enum 2007-01-30 16:01:35 -08:00
ksysfs.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
kthread.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
latency.c [PATCH] severing module.h->sched.h 2006-12-04 02:00:22 -05:00
lockdep.c [PATCH] lockdep: add graph depth information to /proc/lockdep 2007-02-11 10:51:26 -08:00
lockdep_internals.h [PATCH] lockdep: more chains 2006-12-07 08:39:43 -08:00
lockdep_proc.c [PATCH] Fix apparent typo CONFIG_LOCKDEP_DEBUG 2007-02-11 11:18:06 -08:00
Makefile Remove stack unwinder for now 2006-12-15 08:47:51 -08:00
module.c /sys/modules/*/holders 2007-02-07 10:37:12 -08:00
mutex-debug.c [PATCH] lockdep: show more details about self-test failures 2006-12-07 08:39:43 -08:00
mutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
mutex.c [PATCH] lockdep: avoid lockdep warning in md 2006-12-08 08:28:39 -08:00
mutex.h [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
nsproxy.c Revert "[PATCH] namespaces: fix exit race by splitting exit" 2007-01-30 13:35:18 -08:00
panic.c [PATCH] Add TAINT_USER and ability to set taint flags from userspace 2007-02-11 10:51:29 -08:00
params.c /sys/modules/*/holders 2007-02-07 10:37:12 -08:00
pid.c [PATCH] namespaces: fix task exit disaster 2007-01-30 13:40:36 -08:00
posix-cpu-timers.c [PATCH] posix-cpu-timers: prevent signal delivery starvation 2006-10-17 08:18:43 -07:00
posix-timers.c [PATCH] Transform kmem_cache_alloc()+memset(0) -> kmem_cache_zalloc(). 2007-02-11 10:51:27 -08:00
printk.c [PATCH] order of lockdep off/on in vprintk() should be changed 2007-02-11 11:18:06 -08:00
profile.c [PATCH] proc: remove useless (and buggy) ->nlink settings 2007-02-11 10:51:32 -08:00
ptrace.c [PATCH] pidspace: is_init() 2006-09-29 09:18:12 -07:00
rcupdate.c [PATCH] rcu: add a prefetch() in rcu_do_batch() 2006-12-07 08:39:40 -08:00
rcutorture.c [PATCH] rcu: rcutorture suspend fix 2006-12-30 10:55:55 -08:00
relay.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
resource.c devres: device resource management 2007-02-09 17:39:36 -05:00
rtmutex-debug.c Remove all inclusions of <linux/config.h> 2006-10-04 03:38:54 -04:00
rtmutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex-tester.c [PATCH] Add include/linux/freezer.h and move definitions from sched.h 2006-12-07 08:39:27 -08:00
rtmutex.c [PATCH] clean up and remove some extra spinlocks from rtmutex 2006-09-29 09:18:09 -07:00
rtmutex.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex_common.h [PATCH] pi-futex: futex_lock_pi/futex_unlock_pi support 2006-06-27 17:32:47 -07:00
rwsem.c [PATCH] lockdep: prove rwsem locking correctness 2006-07-03 15:27:04 -07:00
sched.c [PATCH] sched: avoid div in rebalance_tick 2007-02-12 09:48:37 -08:00
seccomp.c
signal.c [PATCH] pid: remove the now unused kill_pg kill_pg_info and __kill_pg_info 2007-02-12 09:48:32 -08:00
softirq.c [PATCH] softirq: remove BUG_ONs which can incorrectly trigger 2006-12-07 08:39:43 -08:00
softlockup.c [PATCH] check return value of cpu_callback 2006-09-29 09:18:14 -07:00
spinlock.c [PATCH] lockdep: spin_lock_irqsave_nested() 2006-11-25 13:28:34 -08:00
srcu.c [PATCH] SRCU: report out-of-memory errors 2006-10-04 07:55:30 -07:00
stacktrace.c [PATCH] lockdep: stacktrace subsystem, core 2006-07-03 15:27:02 -07:00
stop_machine.c [PATCH] stop_machine.c copyright 2006-09-29 09:18:24 -07:00
sys.c [PATCH] pid: replace do/while_each_task_pid with do/while_each_pid_task 2007-02-12 09:48:32 -08:00
sys_ni.c [PATCH] Create compat_sys_migrate_pages 2006-11-03 12:27:59 -08:00
sysctl.c [PATCH] _proc_do_string(): fix short reads 2007-02-11 11:18:07 -08:00
taskstats.c [PATCH] taskstats: cleanup reply assembling 2006-12-07 08:39:34 -08:00
time.c [PATCH] NTP: Move all the NTP related code to ntp.c 2006-10-01 00:39:26 -07:00
timer.c [PATCH] Common compat_sys_sysinfo 2007-02-11 10:51:32 -08:00
tsacct.c [PATCH] io-accounting: via taskstats 2006-12-10 09:55:41 -08:00
uid16.c [PATCH] Add more prevent_tail_call() 2006-04-19 16:27:18 -07:00
user.c [PATCH] slab: remove kmem_cache_t 2006-12-07 08:39:25 -08:00
utsname.c [PATCH] namespaces: utsname: implement CLONE_NEWUTS flag 2006-10-02 07:57:22 -07:00
wait.c [PATCH] uninline init_waitqueue_head() 2006-07-10 13:24:25 -07:00
workqueue.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00