Nick Piggin 64c7c8f885 [PATCH] sched: resched and cpu_idle rework ... Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce confusion, and make their semantics rigid. Improves efficiency of resched_task and some cpu_idle routines. * In resched_task: - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held, and as we hold it during resched_task, then there is no need for an atomic test and set there. The only other time this should be set is when the task's quantum expires, in the timer interrupt - this is protected against because the rq lock is irq-safe. - If TIF_NEED_RESCHED is set, then we don't need to do anything. It won't get unset until the task get's schedule()d off. - If we are running on the same CPU as the task we resched, then set TIF_NEED_RESCHED and no further action is required. - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set after TIF_NEED_RESCHED has been set, then we need to send an IPI. Using these rules, we are able to remove the test and set operation in resched_task, and make clear the previously vague semantics of POLLING_NRFLAG. * In idle routines: - Enter cpu_idle with preempt disabled. When the need_resched() condition becomes true, explicitly call schedule(). This makes things a bit clearer (IMO), but haven't updated all architectures yet. - Many do a test and clear of TIF_NEED_RESCHED for some reason. According to the resched_task rules, this isn't needed (and actually breaks the assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock held). So remove that. Generally one less locked memory op when switching to the idle thread. - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner most polling idle loops. The above resched_task semantics allow it to be set until before the last time need_resched() is checked before going into a halt requiring interrupt wakeup. Many idle routines simply never enter such a halt, and so POLLING_NRFLAG can be always left set, completely eliminating resched IPIs when rescheduling the idle task. POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>		2005-11-09 07:56:33 -08:00
..
alpha_ksyms.c
asm-offsets.c
console.c
core_apecs.c
core_cia.c
core_irongate.c
core_lca.c
core_marvel.c
core_mcpcia.c
core_polaris.c
core_t2.c
core_titan.c
core_tsunami.c
core_wildfire.c
entry.S
err_common.c
err_ev6.c
err_ev7.c
err_impl.h
err_marvel.c
err_titan.c
es1888.c
gct.c
head.S
init_task.c
io.c
irq_alpha.c
irq_i8259.c
irq_impl.h
irq_pyxis.c
irq_srm.c
irq.c
machvec_impl.h
Makefile
module.c
ns87312.c
osf_sys.c
pci_impl.h
pci_iommu.c
pci-noop.c
pci.c
process.c	[PATCH] sched: resched and cpu_idle rework	2005-11-09 07:56:33 -08:00
proto.h
ptrace.c
semaphore.c
setup.c
signal.c
smc37c93x.c
smc37c669.c
smp.c
srm_env.c
srmcons.c
sys_alcor.c
sys_cabriolet.c
sys_dp264.c
sys_eb64p.c
sys_eiger.c
sys_jensen.c
sys_marvel.c
sys_miata.c
sys_mikasa.c
sys_nautilus.c
sys_noritake.c
sys_rawhide.c
sys_ruffian.c
sys_rx164.c
sys_sable.c
sys_sio.c
sys_sx164.c
sys_takara.c
sys_titan.c
sys_wildfire.c
systbls.S
time.c	[PATCH] jiffies_64 cleanup	2005-10-30 17:37:25 -08:00
traps.c
vmlinux.lds.S