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linux/kernel
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Eric Dumazet 1bf47346d7 kernel/sys.c: get rid of expensive divides in groups_sort() 
groups_sort() can be quite long if user loads a large gid table.

This is because GROUP_AT(group_info, some_integer) uses an integer divide.
So having to do XXX thousand divides during one syscall can lead to very
high latencies.  (NGROUPS_MAX=65536)

In the past (25 Mar 2006), an analog problem was found in groups_search()
(commit d74beb9f33 ) and at that time I
changed some variables to unsigned int.

I believe that a more generic fix is to make sure NGROUPS_PER_BLOCK is
unsigned.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:09 -08:00
..
irq genirq: stackdump after the "Trying to free already-free IRQ" message 2008-01-30 13:33:24 +01:00
power kernel/power/disk.c: make code static 2008-02-05 09:44:22 -08:00
time time: fix sysfs_show_{available,current}_clocksources() buffer overflow problem 2008-02-06 10:41:03 -08:00
.gitignore
acct.c
audit_tree.c
audit.c [AUDIT] ratelimit printk messages audit 2008-02-01 14:25:04 -05:00
audit.h
auditfilter.c [AUDIT] make audit=0 really stop audit messages 2008-02-01 14:24:33 -05:00
auditsc.c [AUDIT] create context if auditing was ever enabled 2008-02-01 14:24:45 -05:00
backtracetest.c x86: add a simple backtrace test module 2008-01-30 13:33:08 +01:00
capability.c Add 64-bit capability support to the kernel 2008-02-05 09:44:20 -08:00
cgroup_debug.c
cgroup.c
compat.c
configs.c
cpu.c cpu-hotplug: replace per-subsystem mutexes with get_online_cpus() 2008-01-25 21:08:02 +01:00
cpuset.c cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus() 2008-01-25 21:08:02 +01:00
delayacct.c
dma.c
exec_domain.c
exit.c do_wait: remove one "else if" branch 2008-02-06 10:41:04 -08:00
extable.c module: Don't report discarded init pages as kernel text. 2008-01-29 17:13:18 +11:00
fork.c idle_regs() must be __cpuinit 2008-02-06 10:41:08 -08:00
futex_compat.c futex: Add bitset conditional wait/wakeup functionality 2008-02-01 17:45:14 +01:00
futex.c futex: Add bitset conditional wait/wakeup functionality 2008-02-01 17:45:14 +01:00
hrtimer.c timerfd: new timerfd API 2008-02-05 09:44:07 -08:00
itimer.c
kallsyms.c remove support for un-needed _extratext section 2008-02-06 10:41:01 -08:00
Kconfig.hz sched: high-res preemption tick 2008-01-25 21:08:29 +01:00
Kconfig.preempt sched: remove the !PREEMPT_BKL code 2008-01-25 21:08:33 +01:00
kexec.c
kfifo.c
kmod.c Fix unbalanced helper_lock in kernel/kmod.c 2008-01-17 15:38:59 -08:00
kprobes.c x86: kprobes: add kprobes smoke tests that run on boot 2008-01-30 13:32:53 +01:00
ksysfs.c Kobject: convert remaining kobject_unregister() to kobject_put() 2008-01-24 20:40:40 -08:00
kthread.c sched: fix, always create kernel threads with normal priority 2008-01-25 21:08:33 +01:00
latencytop.c sched: latencytop support 2008-01-25 21:08:34 +01:00
lockdep_internals.h
lockdep_proc.c
lockdep.c softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks 2008-01-25 21:08:02 +01:00
Makefile latency.c: use QoS infrastructure 2008-02-05 09:44:22 -08:00
marker.c
module.c x86/non-x86: percpu, node ids, apic ids x86.git fixup 2008-01-30 13:33:32 +01:00
mutex-debug.c
mutex-debug.h
mutex.c
mutex.h
notifier.c kernel/notifier.c should #include <linux/reboot.h> 2008-02-06 10:41:02 -08:00
ns_cgroup.c
nsproxy.c
panic.c debug: add the end-of-trace marker and the module list to 2008-01-30 13:32:50 +01:00
params.c kernel/params.c: remove sparse-warning (different signedness) 2008-02-06 10:41:08 -08:00
pid.c
pm_qos_params.c pm qos infrastructure and interface 2008-02-05 09:44:22 -08:00
posix-cpu-timers.c sched: rt-watchdog: fix .rlim_max = RLIM_INFINITY 2008-01-25 21:08:32 +01:00
posix-timers.c timerfd: new timerfd API 2008-02-05 09:44:07 -08:00
printk.c printk.c: use unsigned ints instead of longs for logbuf index 2008-02-06 10:41:04 -08:00
profile.c debug: clean up kernel/profile.c 2008-01-25 21:08:33 +01:00
ptrace.c kernel/ptrace.c should #include <linux/syscalls.h> 2008-02-06 10:41:02 -08:00
rcuclassic.c Preempt-RCU: implementation 2008-01-25 21:08:24 +01:00
rcupdate.c Preempt-RCU: fix rcu_barrier for preemptive environment. 2008-01-25 21:08:24 +01:00
rcupreempt_trace.c Preempt-RCU: implementation 2008-01-25 21:08:24 +01:00
rcupreempt.c Preempt-RCU: CPU Hotplug handling 2008-01-25 21:08:25 +01:00
rcutorture.c cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus() 2008-01-25 21:08:02 +01:00
relay.c relay: nopage 2008-02-06 10:41:07 -08:00
resource.c
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c Driver core: change sysdev classes to use dynamic kobject names 2008-01-24 20:40:40 -08:00
rtmutex.c
rtmutex.h
rwsem.c
sched_debug.c sched: keep total / count stats in addition to the max for 2008-01-25 21:08:35 +01:00
sched_fair.c sched: let +nice tasks have smaller impact 2008-01-31 22:45:22 +01:00
sched_idletask.c sched: high-res preemption tick 2008-01-25 21:08:29 +01:00
sched_rt.c sched: fix goto retry in pick_next_task_rt() 2008-01-25 21:08:34 +01:00
sched_stats.h
sched.c Merge branch 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc 2008-02-01 11:45:47 +11:00
seccomp.c
signal.c Add arch_ptrace_stop 2008-02-06 10:41:07 -08:00
softirq.c time: track accurate idle time with tick_sched.idle_sleeptime 2008-01-30 13:30:04 +01:00
softlockup.c debug: softlockup looping fix 2008-02-02 14:27:45 +11:00
spinlock.c spinlock: lockbreak cleanup 2008-01-30 13:31:20 +01:00
srcu.c make srcu_readers_active() static 2008-02-06 10:41:02 -08:00
stacktrace.c
stop_machine.c stopmachine: semaphore to mutex 2008-02-06 10:41:08 -08:00
sys_ni.c timerfd: new timerfd API 2008-02-05 09:44:07 -08:00
sys.c kernel/sys.c: get rid of expensive divides in groups_sort() 2008-02-06 10:41:09 -08:00
sysctl_check.c capabilities: introduce per-process capability bounding set 2008-02-05 09:44:20 -08:00
sysctl.c get rid of NR_OPEN and introduce a sysctl_nr_open 2008-02-06 10:41:06 -08:00
taskstats.c
test_kprobes.c x86: kprobes: add kprobes smoke tests that run on boot 2008-01-30 13:32:53 +01:00
time.c timekeeping: update xtime_cache when time(zone) changes 2008-02-01 17:45:13 +01:00
timer.c taskstats scaled time cleanup 2008-02-06 10:41:00 -08:00
tsacct.c
uid16.c
user_namespace.c
user.c uids: merge multiple error paths in alloc_uid() into one 2008-01-25 21:08:26 +01:00
utsname_sysctl.c
utsname.c
wait.c
workqueue.c cpu-hotplug: replace per-subsystem mutexes with get_online_cpus() 2008-01-25 21:08:02 +01:00