linux/arch
Pallipadi, Venkatesh a59d1637eb ACPI: cap off P-state transition latency from buggy BIOSes
Some BIOSes report very high frequency transition latency which are plainly
wrong on CPus that can change frequency using native MSR interface.

One such system is IBM T42 (2327-8ZU) as reported by Owen Taylor and
Rik van Riel.

cpufreq_ondemand driver uses this transition latency to come up with a
reasonable sampling interval to sample CPU usage and with such high
latency value, ondemand sampling interval ends up being very high
(0.5 sec, in this particular case), resulting in performance impact due to
slow response to increasing frequency.

Fix it by capping-off the transition latency to 20uS for native MSR based
frequency transitions.

mjg: We've confirmed that this also helps on the X31

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-03-27 21:21:09 -04:00
..
alpha cpumask: Use cpu_*_mask accessors code: alpha 2009-02-16 17:32:00 +10:30
arm Merge master.kernel.org:/home/rmk/linux-2.6-arm 2009-03-15 13:34:56 -07:00
avr32 [ARM] 5400/1: Add support for inverted rdy_busy pin for Atmel nand device controller 2009-02-16 21:40:39 +00:00
blackfin Blackfin arch: SPI_MMC is now mainlined MMC_SPI 2009-03-06 00:27:57 +08:00
cris Merge branch 'syscalls' of git://git390.osdl.marist.edu/pub/scm/linux-2.6 2009-01-14 19:58:40 -08:00
frv FRV: in_interrupt() requires #inclusion of linux/hardirq.h not asm/hardirq.h now 2009-02-09 08:51:35 -08:00
h8300 Merge branch 'syscalls' of git://git390.osdl.marist.edu/pub/scm/linux-2.6 2009-01-14 19:58:40 -08:00
ia64 [IA64] fix PCI DMA flag propagation on SN (Altix) with PICs 2009-03-06 10:41:13 -08:00
m32r eeprom: More consistent symbol names 2009-01-26 21:19:57 +01:00
m68k m68k: merge the non-MMU and MMU versions of siginfo.h 2009-03-17 08:47:11 +10:00
m68knommu m68knommu: m528x build fix 2009-03-10 15:55:12 -07:00
mips MIPS: Mark Eins: Fix configuration. 2009-03-13 23:08:00 +01:00
mn10300 mn10300: fix typo && -> || in arch/mn10300/unit-asb2305/pci.c 2009-02-20 17:57:48 -08:00
parisc parisc: update defconfigs 2009-03-13 01:33:34 -04:00
powerpc powerpc/mm: Fix Respect _PAGE_COHERENT on classic ppc32 SW TLB load machines 2009-03-23 08:38:26 -05:00
s390 [S390] make page table upgrade work again 2009-03-18 13:28:13 +01:00
sh sh: Add media/soc_camera.h to board setup of Renesas AP325RXA 2009-03-10 15:20:54 +09:00
sparc Merge branch 'master' of /home/davem/src/GIT/linux-2.6/ 2009-03-18 23:53:57 -07:00
um uml: fix WARNING: vmlinux: 'memcpy' exported twice 2009-03-12 16:20:23 -07:00
x86 ACPI: cap off P-state transition latency from buggy BIOSes 2009-03-27 21:21:09 -04:00
xtensa xtensa: fix compilation somewhat 2009-03-10 15:55:10 -07:00
.gitignore
Kconfig [CVE-2009-0029] System call wrapper infrastructure 2009-01-14 14:15:16 +01:00