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1e185b97b4
linux/arch/ia64/kernel
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Chen, Kenneth W 1e185b97b4 [PATCH] ia64: cpu_idle performance bug fix 
Our performance validation on 2.6.15-rc1 caught a disastrous performance
regression on ia64 with netperf (-98%) and volanomark (-58%) compares to
previous kernel version 2.6.14-git7.  See the following chart (result
group 1 & 2).

  http://kernel-perf.sourceforge.net/results.machine_id=26.html

We have root caused it to commit 64c7c8f885

This changeset broke the ia64 task resched notification.  In
sched.c:resched_task(), a reschedule IPI is conditioned upon
TIF_POLLING_NRFLAG.  However, the above changeset unconditionally set
the polling thread flag for idle tasks regardless whether pal_halt_light
is in use or not.  As a result, resched IPI is not sent from
resched_task().  And since the default behavior on ia64 is to use
pal_halt_light, we end up delaying the rescheduling task until next
timer tick, and thus cause the performance regression.

This fixes the performance bug.  I'm glad our performance suite is
turning up bad performance bug like this in time.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-15 15:50:51 -08:00
..
cpufreq [IA64] Add ACPI based P-state support 2005-08-26 15:09:24 -07:00
acpi-ext.c [ACPI] Lindent all ACPI files 2005-08-05 00:45:14 -04:00
acpi.c [IA64] move ACPI IOSAPIC locality domain mapping from pci.c to acpi.c 2005-09-19 15:57:48 -07:00
asm-offsets.c [IA64] fix circular dependency on generation of asm-offsets.h 2005-09-13 08:50:39 -07:00
brl_emu.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cyclone.c [PATCH] fix missing includes 2005-10-30 17:37:32 -08:00
efi_stub.S Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
efi.c [IA64] Replace kcalloc(1, with kzalloc. 2005-11-10 11:28:20 -08:00
entry.h [IA64] Drop spurious paren in entry.h 2005-06-20 09:34:02 -07:00
entry.S [IA64] Remove warnings for gcc 4.0 IA64 compilation. 2005-09-16 09:45:27 -07:00
fsys.S kbuild: ia64 use generic asm-offsets.h support 2005-09-09 22:03:13 +02:00
gate-data.S Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
gate.lds.S Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
gate.S kbuild: ia64 use generic asm-offsets.h support 2005-09-09 22:03:13 +02:00
head.S kbuild: ia64 use generic asm-offsets.h support 2005-09-09 22:03:13 +02:00
ia64_ksyms.c [IA64] __ia64_syscall() is no longer used anywhere in the kernel. Remove it. 2005-04-27 21:10:45 -07:00
init_task.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
iosapic.c [IA64] Manual merge fix for 3 files 2005-09-08 14:27:13 -07:00
irq_ia64.c [IA64] assign_irq_vector() should not panic 2005-07-11 10:30:07 -07:00
irq_lsapic.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irq.c [IA64] wider use of for_each_cpu_mask() in arch/ia64 2005-10-25 15:10:08 -07:00
ivt.S [IA64] 4-level page tables 2005-11-11 09:37:29 -08:00
jprobes.S [PATCH] Kprobes: prevent possible race conditions ia64 changes 2005-09-07 16:58:00 -07:00
kprobes.c [IA64] Extend notify_die() hooks for IA64 2005-11-07 11:27:13 -08:00
machvec.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Makefile [PATCH] cpusets: Move the ia64 domain setup code to the generic code 2005-09-07 16:57:40 -07:00
mca_asm.S [IA64] Wire in the MCA/INIT handler stacks 2005-09-22 13:24:19 -07:00
mca_drv_asm.S [IA64] mca_drv cleanup 2005-09-16 10:39:40 -07:00
mca_drv.c Pull mca-check-psp into release branch 2005-11-10 10:38:05 -08:00
mca_drv.h [IA64] mca_drv cleanup 2005-09-16 10:39:40 -07:00
mca.c [IA64] Extend notify_die() hooks for IA64 2005-11-07 11:27:13 -08:00
minstate.h [IA64] MCA/INIT: remove the physical mode path from minstate.h 2005-09-11 14:09:12 -07:00
module.c [IA64] wider use of for_each_cpu_mask() in arch/ia64 2005-10-25 15:10:08 -07:00
numa.c [IA64] fix generic/up builds 2005-07-06 18:18:10 -07:00
pal.S Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
palinfo.c [IA64] Allow /proc/pal/cpu0/vm_info under the simulator 2005-08-31 08:34:51 -07:00
patch.c [IA64] Fix 2.6 kernel for the new ia64 assembler 2005-10-25 15:05:45 -07:00
perfmon_default_smpl.c [IA64] perfmon: make pfm_sysctl a global, and other cleanup 2005-04-25 13:08:30 -07:00
perfmon_generic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
perfmon_itanium.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
perfmon_mckinley.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
perfmon.c [PATCH] kfree cleanup: arch 2005-11-07 07:54:06 -08:00
process.c [PATCH] ia64: cpu_idle performance bug fix 2005-11-15 15:50:51 -08:00
ptrace.c [IA64] fix warning unused variable `g' 2005-10-28 15:52:13 -07:00
sal.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
salinfo.c [IA64] MCA/INIT: avoid reading INIT record during INIT event 2005-09-11 14:02:43 -07:00
semaphore.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
setup.c Pull context-bitmap into release branch 2005-11-10 10:39:49 -08:00
sigframe.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.c [IA64] align signal-frame even when not using alternate signal-stack 2005-11-08 09:58:06 -08:00
smp.c [IA64] wider use of for_each_cpu_mask() in arch/ia64 2005-10-25 15:10:08 -07:00
smpboot.c [PATCH] sched: disable preempt in idle tasks 2005-11-09 07:56:33 -08:00
sys_ia64.c [IA64] Rationalise Region Definitions 2005-08-24 15:35:41 -07:00
time.c [PATCH] jiffies_64 cleanup 2005-10-30 17:37:25 -08:00
topology.c [ACPI] delete CONFIG_ACPI_BOOT 2005-08-24 12:08:54 -04:00
traps.c [IA64] Extend notify_die() hooks for IA64 2005-11-07 11:27:13 -08:00
unaligned.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
uncached.c [IA64] simplified efi memory map parsing 2005-09-08 12:39:59 -07:00
unwind_decoder.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unwind_i.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unwind.c [IA64] MCA/INIT: remove obsolete unwind code 2005-09-11 14:09:34 -07:00
vmlinux.lds.S [PATCH] Kprobes: prevent possible race conditions ia64 changes 2005-09-07 16:58:00 -07:00