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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>		19 years ago
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vdso32	[PATCH] ppc64: Fix error in vDSO 32 bits date	20 years ago
vdso64	powerpc: Make some #includes explicit.	20 years ago
Makefile	powerpc: Merge smp.c and smp.h	19 years ago
align.c	[PATCH] powerpc: Fix handling of fpscr on 64-bit	20 years ago
asm-offsets.c	[PATCH] ppc64: support 64k pages	19 years ago
btext.c	ppc64: Rearrange btext initialization for consistency with ppc32	20 years ago
cpu_setup_power4.S	[PATCH] merge some from Rusty's trivial patches	20 years ago
dma.c	[PATCH] gfp flags annotations - part 1	20 years ago
eeh.c	powerpc: Move iSeries_pci.c to powerpc/platform/iseries	20 years ago
firmware.c	[PATCH] ppc64: make firmware_has_feature() stronger	20 years ago
head.S	[PATCH] ppc64: support 64k pages	19 years ago
hvconsole.c	[PATCH] hvc_console: Separate the NUL character filtering from get_hvc_chars	20 years ago
hvcserver.c	[PATCH] fix missing includes	19 years ago
idle.c	[PATCH] sched: resched and cpu_idle rework	19 years ago
ioctl32.c	[PATCH] TIOC* compat ioctl handling	19 years ago
iomap.c	Merge master.kernel.org:/pub/scm/linux/kernel/git/paulus/ppc64-2.6	20 years ago
iommu.c	[PATCH] gfp flags annotations - part 1	20 years ago
irq.c	Merge iSeries include file move	19 years ago
kprobes.c	[PATCH] Kprobes: preempt_disable/enable() simplification	19 years ago
lparcfg.c	[PATCH] kfree cleanup: arch	19 years ago
machine_kexec.c	powerpc: Various UP build fixes	19 years ago
misc.S	[PATCH] ppc64: SMU based macs cpufreq support	19 years ago
module.c	[PATCH] ppc64: Add R_PPC64_TOC16 module reloc	20 years ago
nvram.c	[PATCH] ppc64: simplify nvram partition scanning code	20 years ago
pacaData.c	[PATCH] ppc64: support 64k pages	19 years ago
pci.c	[PATCH] dlpar enable for OF pci probe	19 years ago
pci_direct_iommu.c	Merge from Linus' tree	20 years ago
pci_dn.c	[PATCH] ppc64: Fix add notifier crashes	19 years ago
pci_iommu.c	powerpc: move iSeries/iSeries_pci.h to platforms/iseries	20 years ago
ppc_ksyms.c	powerpc: move more iSeries code	20 years ago
proc_ppc64.c	[PATCH] powerpc: Rename BPA to Cell	19 years ago
prom.c	[PATCH] ppc64: SMU partition recovery	19 years ago
prom_init.c	[PATCH] ppc64: More U3 device-tree fixes	19 years ago
rtas_pci.c	[PATCH] dlpar enable for OF pci probe	19 years ago
rtc.c	powerpc: Merge machdep.h	20 years ago
scanlog.c	[PATCH] kfree cleanup: arch	19 years ago
semaphore.c	…
sysfs.c	[PATCH] POWERPC/PPC64: Fix CONFIG_SMP=n build for ppc64	19 years ago
udbg.c	[PATCH] powerpc: Kill ppcdebug	19 years ago
udbg_16550.c	[PATCH] ppc64: Remove old includes	20 years ago
udbg_scc.c	[PATCH] powerpc: Move naca.h to platforms/iseries	19 years ago
vdso.c	[PATCH] core remove PageReserved	19 years ago
vmlinux.lds.S	powerpc: Reduce the 32/64-bit diffs in vmlinux.lds.S	20 years ago