In an effort to be fair to bound processes,
acpi_pad periodically moves its forced-idle threads.
The default interval for moving the threads is 10 seconds.
Measurements show that reducing this to 1 second has no
power or performance impact, so reduce default to 1 second.
Signed-off-by: Len Brown <len.brown@intel.com>
The acpi_pad driver can get stuck in destroy_power_saving_task()
waiting for kthread_stop() to stop a power_saving thread. The problem
is that the isolated_cpus_lock mutex is owned when
destroy_power_saving_task() calls kthread_stop(), which waits for a
power_saving thread to end, and the power_saving thread tries to
acquire the isolated_cpus_lock when it calls round_robin_cpu(). This
patch fixes the issue by making round_robin_cpu() use its own mutex.
https://bugzilla.kernel.org/show_bug.cgi?id=42981
Cc: stable@vger.kernel.org
Signed-off-by: Stuart Hayes <Stuart_Hayes@Dell.com>
Signed-off-by: Len Brown <len.brown@intel.com>
"acpi_pad/%d" is a better thread name than
generic "power_saving/%d" because users who see
these threads will know the name of the driver
that caused them.
Signed-off-by: Len Brown <len.brown@intel.com>
Make /sys output from acpi_pad more readable.
Before the fix:
# cat idlecpus idlepct rrtime
00000000510
After the fix:
# cat idlecpus idlepct rrtime
00000000
5
10
Signed-off-by: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
* 'x86-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, hotplug: In the MWAIT case of play_dead, CLFLUSH the cache line
x86, hotplug: Move WBINVD back outside the play_dead loop
x86, hotplug: Use mwait to offline a processor, fix the legacy case
x86, mwait: Move mwait constants to a common header file
acpi_pad.c:432: warning: ‘num_cpus’ may be used uninitialized in this function
gcc 4.4.4 was unable to notice that num_cpus is always set.
Re-arrange the code to un-confuse gcc, and also make
it easier for humans to read....
Signed-off-by: Len Brown <len.browns@intel.com>
We have MWAIT constants spread across three different .c files, for no
good reason. Move them all into a common header file.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
LKML-Reference: <tip-*@git.kernel.org>
Now that all arches have been converted over to use generic time via
clocksources or arch_gettimeoffset(), we can remove the GENERIC_TIME
config option and simplify the generic code.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-4-git-send-email-johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
As suggested in Venki's suggestion in the commit 0dc698b,
add LAPIC unstable detection in the acpi_pad drvier too.
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
* 'idle-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6:
intel_idle: native hardware cpuidle driver for latest Intel processors
ACPI: acpi_idle: touch TS_POLLING only in the non-MWAIT case
acpi_pad: uses MONITOR/MWAIT, so it doesn't need to clear TS_POLLING
sched: clarify commment for TS_POLLING
ACPI: allow a native cpuidle driver to displace ACPI
cpuidle: make cpuidle_curr_driver static
cpuidle: add cpuidle_unregister_driver() error check
cpuidle: fail to register if !CONFIG_CPU_IDLE
acpi pad driver kind of aggressively marks TSC as unstable at init
time, on mwait capable and non X86_FEATURE_NONSTOP_TSC systems. This is
irrespective of whether pad driver is ever going to be used on the
system or deep C-states are supported/used. This will affect every user
who just happens to compile in (or get a kernel version which
compiles in) acpi pad driver.
Move mark_tsc_unstable() out of init to the actual idle invocation path
of the pad driver.
There is also another bug/missing_feature in the code that it does not
support 'always running apic timer' and switches to broadcast mode
unconditionally. Shaohua, can you take a look at that please.
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Len Brown <len.brown@intel.com>
api_pad exclusively uses MONITOR/MWAIT to sleep in idle,
so it does not need the wakeup IPI during idle sleep
that is provoked by clearing TS_POLLING.
Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Shaohua Li <shaohua.li@intel.com>
cpi_device_class can only be 19 characters and a NULL terminator.
With the current name we get a buffer overflow in acpi_pad_add()
strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
[akpm@linux-foundation.org: call it acpi_pad, per Shaohua Li]
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: walter harms <wharms@bfs.de>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
There are some fixes listed below:
1. When met a bogus BIOS, the return value of cpu number maybe is
a negative value so that acpi_pad_pur get an unexpected result.
2. the return value of function acpi_pad_idle_cpus is useless.
3. enhance the process of create_power_saving_task/destroy_power_saving_task
4. Add more error checks when evaluating _PUR object.
5. one typo fix
Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
drivers/acpi/acpi_pad.c: In function 'power_saving_thread':
drivers/acpi/acpi_pad.c:103: warning: 'preferred_cpu' may be used uninitialized in this function
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
ACPI 4.0 created the logical "processor aggregator device" as
a mechinism for platforms to ask the OS to force otherwise busy
processors to enter (power saving) idle.
The intent is to lower power consumption to ride-out
transient electrical and thermal emergencies,
rather than powering off the server.
On platforms that can save more power/performance via P-states,
the platform will first exhaust P-states before forcing idle.
However, the relative benefit of P-states vs. idle states
is platform dependent, and thus this driver need not know
or care about it.
This driver does not use the kernel's CPU hot-plug mechanism
because after the transient emergency is over, the system must
be returned to its normal state, and hotplug would permanently
break both cpusets and binding.
So to force idle, the driver creates a power saving thread.
The scheduler will migrate the thread to the preferred CPU.
The thread has max priority and has SCHED_RR policy,
so it can occupy one CPU. To save power, the thread will
invoke the deep C-state entry instructions.
To avoid starvation, the thread will sleep 5% of the time
time for every second (current RT scheduler has threshold
to avoid starvation, but if other CPUs are idle,
the CPU can borrow CPU timer from other,
which makes the mechanism not work here)
Vaidyanathan Srinivasan has proposed scheduler enhancements
to allow injecting idle time into the system. This driver doesn't
depend on those enhancements, but could cut over to them
when they are available.
Peter Z. does not favor upstreaming this driver until
the those scheduler enhancements are in place. However,
we favor upstreaming this driver now because it is useful
now, and can be enhanced over time.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
NACKed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Len Brown <len.brown@intel.com>
