Martin Andersson 013d386814 [PATCH] sched: fix task interactivity calculation ... Is a truncation error in kernel/sched.c triggered when the nice value is negative. The affected code is used in the TASK_INTERACTIVE macro. The code is: #define SCALE(v1,v1_max,v2_max) \ (v1) * (v2_max) / (v1_max) which is used in this way: SCALE(TASK_NICE(p), 40, MAX_BONUS) Comments in the code says: * This part scales the interactivity limit depending on niceness. * * We scale it linearly, offset by the INTERACTIVE_DELTA delta. * Here are a few examples of different nice levels: * * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0] * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0] * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0] * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0] * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0] * * (the X axis represents the possible -5 ... 0 ... +5 dynamic * priority range a task can explore, a value of '1' means the * task is rated interactive.) However, the current code does not scale it linearly and the result differs from the given examples. If the mathematical function "floor" is used when the nice value is negative instead of the truncation one gets when using integer division, the result conforms to the documentation. Output of TASK_INTERACTIVE when using the kernel code: nice dynamic priorities -20 1 1 1 1 1 1 1 1 1 0 0 -19 1 1 1 1 1 1 1 1 0 0 0 -18 1 1 1 1 1 1 1 1 0 0 0 -17 1 1 1 1 1 1 1 1 0 0 0 -16 1 1 1 1 1 1 1 1 0 0 0 -15 1 1 1 1 1 1 1 0 0 0 0 -14 1 1 1 1 1 1 1 0 0 0 0 -13 1 1 1 1 1 1 1 0 0 0 0 -12 1 1 1 1 1 1 1 0 0 0 0 -11 1 1 1 1 1 1 0 0 0 0 0 -10 1 1 1 1 1 1 0 0 0 0 0 -9 1 1 1 1 1 1 0 0 0 0 0 -8 1 1 1 1 1 1 0 0 0 0 0 -7 1 1 1 1 1 0 0 0 0 0 0 -6 1 1 1 1 1 0 0 0 0 0 0 -5 1 1 1 1 1 0 0 0 0 0 0 -4 1 1 1 1 1 0 0 0 0 0 0 -3 1 1 1 1 0 0 0 0 0 0 0 -2 1 1 1 1 0 0 0 0 0 0 0 -1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 2 1 1 1 1 0 0 0 0 0 0 0 3 1 1 1 1 0 0 0 0 0 0 0 4 1 1 1 0 0 0 0 0 0 0 0 5 1 1 1 0 0 0 0 0 0 0 0 6 1 1 1 0 0 0 0 0 0 0 0 7 1 1 1 0 0 0 0 0 0 0 0 8 1 1 0 0 0 0 0 0 0 0 0 9 1 1 0 0 0 0 0 0 0 0 0 10 1 1 0 0 0 0 0 0 0 0 0 11 1 1 0 0 0 0 0 0 0 0 0 12 1 0 0 0 0 0 0 0 0 0 0 13 1 0 0 0 0 0 0 0 0 0 0 14 1 0 0 0 0 0 0 0 0 0 0 15 1 0 0 0 0 0 0 0 0 0 0 16 0 0 0 0 0 0 0 0 0 0 0 17 0 0 0 0 0 0 0 0 0 0 0 18 0 0 0 0 0 0 0 0 0 0 0 19 0 0 0 0 0 0 0 0 0 0 0 Output of TASK_INTERACTIVE when using "floor" nice dynamic priorities -20 1 1 1 1 1 1 1 1 1 0 0 -19 1 1 1 1 1 1 1 1 1 0 0 -18 1 1 1 1 1 1 1 1 1 0 0 -17 1 1 1 1 1 1 1 1 1 0 0 -16 1 1 1 1 1 1 1 1 0 0 0 -15 1 1 1 1 1 1 1 1 0 0 0 -14 1 1 1 1 1 1 1 1 0 0 0 -13 1 1 1 1 1 1 1 1 0 0 0 -12 1 1 1 1 1 1 1 0 0 0 0 -11 1 1 1 1 1 1 1 0 0 0 0 -10 1 1 1 1 1 1 1 0 0 0 0 -9 1 1 1 1 1 1 1 0 0 0 0 -8 1 1 1 1 1 1 0 0 0 0 0 -7 1 1 1 1 1 1 0 0 0 0 0 -6 1 1 1 1 1 1 0 0 0 0 0 -5 1 1 1 1 1 1 0 0 0 0 0 -4 1 1 1 1 1 0 0 0 0 0 0 -3 1 1 1 1 1 0 0 0 0 0 0 -2 1 1 1 1 1 0 0 0 0 0 0 -1 1 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 2 1 1 1 1 0 0 0 0 0 0 0 3 1 1 1 1 0 0 0 0 0 0 0 4 1 1 1 0 0 0 0 0 0 0 0 5 1 1 1 0 0 0 0 0 0 0 0 6 1 1 1 0 0 0 0 0 0 0 0 7 1 1 1 0 0 0 0 0 0 0 0 8 1 1 0 0 0 0 0 0 0 0 0 9 1 1 0 0 0 0 0 0 0 0 0 10 1 1 0 0 0 0 0 0 0 0 0 11 1 1 0 0 0 0 0 0 0 0 0 12 1 0 0 0 0 0 0 0 0 0 0 13 1 0 0 0 0 0 0 0 0 0 0 14 1 0 0 0 0 0 0 0 0 0 0 15 1 0 0 0 0 0 0 0 0 0 0 16 0 0 0 0 0 0 0 0 0 0 0 17 0 0 0 0 0 0 0 0 0 0 0 18 0 0 0 0 0 0 0 0 0 0 0 19 0 0 0 0 0 0 0 0 0 0 0 Signed-off-by: Martin Andersson <martin.andersson@control.lth.se> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Williams <pwil3058@bigpond.net.au> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>		2006-03-27 08:44:43 -08:00
..
irq	[PATCH] warn if free_irq() is called from IRQ context	2006-03-26 08:56:53 -08:00
power	[PATCH] swswsup: return correct load_image error	2006-03-26 08:56:55 -08:00
.gitignore
acct.c
audit.c
audit.h
auditfilter.c
auditsc.c	Merge branch 'audit.b3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current	2006-03-25 09:24:53 -08:00
capability.c	[PATCH] refactor capable() to one implementation, add __capable() helper	2006-03-25 08:22:56 -08:00
compat.c	[PATCH] consolidate sys32/compat_adjtimex	2006-03-26 08:56:57 -08:00
configs.c
cpu.c	BUG_ON() Conversion in kernel/cpu.c	2006-03-24 18:45:21 +01:00
cpuset.c	[PATCH] cpuset: remove useless local variable initialization	2006-03-24 07:33:24 -08:00
dma.c
exec_domain.c	[PATCH] Fix module refcount leak in __set_personality()	2006-03-24 07:33:30 -08:00
exit.c
extable.c
fork.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial	2006-03-26 09:41:18 -08:00
futex.c
hrtimer.c	[PATCH] hrtimers: remove data field	2006-03-26 08:57:03 -08:00
intermodule.c
itimer.c	[PATCH] hrtimers: remove data field	2006-03-26 08:57:03 -08:00
kallsyms.c
Kconfig.hz
Kconfig.preempt
kexec.c
kfifo.c
kmod.c
kprobes.c	[PATCH] kretprobe instance recycled by parent process	2006-03-26 08:57:04 -08:00
ksysfs.c	[PATCH] fix build error if CONFIG_SYSFS=n	2006-03-24 07:33:31 -08:00
kthread.c	[PATCH] find_task_by_pid() needs tasklist_lock	2006-03-25 08:22:57 -08:00
Makefile	Merge branch 'audit.b3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit-current	2006-03-25 09:24:53 -08:00
module.c	[PATCH] Remove MODULE_PARM	2006-03-25 08:22:52 -08:00
mutex-debug.c
mutex-debug.h
mutex.c
mutex.h
panic.c
params.c	[PATCH] kernel/params.c: make param_array() static	2006-03-25 08:22:52 -08:00
pid.c
posix-cpu-timers.c
posix-timers.c	[PATCH] hrtimers: remove data field	2006-03-26 08:57:03 -08:00
printk.c	[PATCH] console_setup() depends (wrongly?) on CONFIG_PRINTK	2006-03-24 07:33:27 -08:00
profile.c
ptrace.c
rcupdate.c
rcutorture.c	[PATCH] Remove MODULE_PARM	2006-03-25 08:22:52 -08:00
relay.c
resource.c
sched.c	[PATCH] sched: fix task interactivity calculation	2006-03-27 08:44:43 -08:00
seccomp.c
signal.c
softirq.c
softlockup.c	[PATCH] timer irq driven soft watchdog fix	2006-03-25 08:22:48 -08:00
spinlock.c
stop_machine.c
sys_ni.c
sys.c	[PATCH] Use unsigned int types for a faster bsearch	2006-03-25 08:23:01 -08:00
sysctl.c
time.c	[PATCH] hrtimers: remove nsec_t typedef	2006-03-26 08:57:03 -08:00
timer.c	[PATCH] remove pps support	2006-03-25 08:23:02 -08:00
uid16.c
user.c
wait.c
workqueue.c