2012/10/29 Steven Rostedt rost...@goodmis.org:
On Mon, 2012-10-29 at 14:28 +0100, Frederic Weisbecker wrote:
This prepares us to make printk working on nohz CPUs
using irq work.
-ENOTENOUGHINFO
Please state how this prepares printk for nohz CPUS using irq_work.
RIght, I'll add the details
2012/10/29 Steven Rostedt rost...@goodmis.org:
On Mon, 2012-10-29 at 14:28 +0100, Frederic Weisbecker wrote:
klogd is woken up asynchronously from the tick in order
to do it safely.
However if printk is called when the tick is stopped, the reader
won't be woken up until the next interrupt
a bit scattered around
* Separate irqtime and vtime namespaces that were
colliding, resulting in useless calls to irqtime accounting.
* Slightly optimize irq and guest vtime accounting.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt rost...@goodmis.org
Cc: Paul Gortmaker paul.gortma...@windriver.com
---
kernel
in claim) execute_work (sees data from CPU 0)
try to claim
As a shortcut, let's just use xchg() that implies a full memory
barrier.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
Hi,
The first patch is extracted from my printk patches, with changelog
reworked. The second patch is an addition.
And I still wonder if cpu_relax() is enough to prevent the compiler
from correctly reloading work-flags in irq_work_sync() loop.
Do we need ACCESS_ONCE()?
Thanks.
Frederic
2012/10/30 Steven Rostedt rost...@goodmis.org:
On Tue, 2012-10-30 at 16:34 +0100, Frederic Weisbecker wrote:
Hi,
And I still wonder if cpu_relax() is enough to prevent the compiler
from correctly reloading work-flags in irq_work_sync() loop.
Do we need ACCESS_ONCE()?
You mean this loop
2012/10/30 Steven Rostedt rost...@goodmis.org:
On Tue, 2012-10-30 at 17:25 +0100, Frederic Weisbecker wrote:
No I was worried about the cpu_relax() in irq_work_sync()
That one is fine too, as this is the purpose of cpu_relax(). Not only to
relax the cpu, but also to tell gcc that the loop
2012/10/30 Steven Rostedt rost...@goodmis.org:
On Mon, 2012-10-29 at 16:27 -0400, Steven Rostedt wrote:
plain text document attachment
(0004-x86-New-cpuset-nohz-irq-vector.patch)
From: Frederic Weisbecker fweis...@gmail.com
We need a way to send an IPI (remote or local) in order
2012/10/30 Steven Rostedt rost...@goodmis.org:
Probably need to at least disable preemption. I don't see any
requirement that wake_up_klogd() needs to be called with preemption
disabled.
The this_cpu_or() doesn't care which CPU it triggers, but the enabling
of nohz does.
This patch is
2012/10/30 anish kumar anish198519851...@gmail.com:
As I understand without the memory barrier proposed by you the situation
would be as below:
CPU 0 CPU 1
data = something flags = IRQ_WORK_BUSY
smp_mb() (implicit with cmpxchg
2012/10/31 Steven Rostedt rost...@goodmis.org:
On Wed, 2012-10-31 at 00:51 +0100, Frederic Weisbecker wrote:
Probably just use irq_work for self ipis, and normal ipis for other
CPUs.
Right. And that's one more reason why we want to know if the arch
implements irq work with self ipis
2012/10/31 Steven Rostedt rost...@goodmis.org:
More confidence over what? The xchg()? They are equivalent (wrt memory
barriers).
Here's the issue that currently exists. Let's look at the code:
/*
* Claim the entry so that no one else will poke at it.
*/
static bool
2012/10/31 Steven Rostedt rost...@goodmis.org:
On Wed, 2012-10-31 at 20:04 +0900, anish kumar wrote:
nflags = 1 | 3
nflags = 2 | 3
In both cases the result would be same.If I am right then wouldn't this
operation be redundant?
Right. Actually we could change the new loop to:
for
2012/10/31 Paul E. McKenney paul...@linux.vnet.ibm.com:
+/*
+ * Per-rcu_data kthread, but only for no-CBs CPUs. Each kthread invokes
+ * callbacks queued by the corresponding no-CBs CPU.
+ */
+static int rcu_nocb_kthread(void *arg)
+{
+ int c, cl;
+ struct rcu_head *list;
+
Hey,
After some discussion with Steve, this is a respin with changelogs and
comments sanitized. The code itself hasn't changed.
Thanks.
Frederic Weisbecker (2):
irq_work: Fix racy IRQ_WORK_BUSY flag setting
irq_work: Fix racy check on work pending flag
kernel/irq_work.c | 21
ordering.
Changelog-heavily-inspired-by: Steven Rostedt rost...@goodmis.org
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt
the value we wish to be
in the work-flags but we only make any conclusion after the value
returned by the cmpxchg() call that either claims the work or let
the current owner handle the pending work for us.
Changelog-heavily-inspired-by: Steven Rostedt rost...@goodmis.org
Signed-off-by: Frederic
2012/9/22 Paul E. McKenney paul...@linux.vnet.ibm.com:
On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote:
* Paul E. McKenney paul...@linux.vnet.ibm.com [120921 12:58]:
Just to make sure I understand the combinations:
o All stalls have happened when running a minimal
2012/9/23 Sasha Levin levinsasha...@gmail.com:
On 09/23/2012 02:21 AM, Paul E. McKenney wrote:
On Sat, Sep 22, 2012 at 02:27:35PM -0700, Paul E. McKenney wrote:
On Sat, Sep 22, 2012 at 07:50:29PM +0200, Sasha Levin wrote:
On 09/22/2012 05:56 PM, Paul E. McKenney wrote:
And now the prime
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 12:47 AM, Sasha Levin wrote:
- While I no longer see the warnings I've originally noticed, if I run with
Paul's last debug patch I see the following warning:
Correction: Original warnings are still there, they just got buried in
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 01:06 AM, Frederic Weisbecker wrote:
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 12:47 AM, Sasha Levin wrote:
- While I no longer see the warnings I've originally noticed, if I run
with Paul's last debug patch I
2012/9/25 Frederic Weisbecker fweis...@gmail.com:
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 01:06 AM, Frederic Weisbecker wrote:
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 12:47 AM, Sasha Levin wrote:
- While I no longer see the warnings I've originally
On Mon, Sep 24, 2012 at 09:04:20PM -0700, Paul E. McKenney wrote:
On Tue, Sep 25, 2012 at 01:41:18AM +0200, Frederic Weisbecker wrote:
[ 168.703017] [ cut here ]
[ 168.708117] WARNING: at kernel/rcutree.c:502
rcu_eqs_exit_common+0x4a/0x3a0()
[ 168.710034
On Tue, Sep 25, 2012 at 01:10:27AM +0200, Sasha Levin wrote:
On 09/25/2012 01:06 AM, Frederic Weisbecker wrote:
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 12:47 AM, Sasha Levin wrote:
- While I no longer see the warnings I've originally noticed, if I run
with Paul's
Cleanup the label maze in this function. Having a
seperate function to first handle the traps that don't
generate a signal makes it easier to convert into
more readable conditional paths.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar
option (reported by Russell King)
Please pull from:
git://github.com/fweisbec/linux-dynticks.git
cputime/cleanups-v2
It is based on tip:sched/core
Thanks.
Frederic Weisbecker (6):
cputime: Use a proper subsystem naming for vtime related APIs
vtime: Consolidate system/idle context
to find out the context we account to from generic code.
This also make it better to know on which subsystem these APIs
refer to.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b
the generic code to decide when to call which API.
Archs that have their own meaning of idle time, such as s390
that only considers the time spent in CPU low power mode as idle
time, can just override vtime_account().
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc
Factorize the code that accounts user time into a
single function to avoid code duplication.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b...@kernel.crashing.org
Cc: Paul Mackerras pau
To avoid code duplication.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b...@kernel.crashing.org
Cc: Paul Mackerras pau...@samba.org
Cc: Martin Schwidefsky schwidef...@de.ibm.com
Cc: Heiko
This debloats a bit the general config menu and make these
config options easier to find.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b...@kernel.crashing.org
Cc: Paul Mackerras pau
.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b...@kernel.crashing.org
Cc: Paul Mackerras pau...@samba.org
Cc: Martin Schwidefsky schwidef...@de.ibm.com
Cc: Heiko Carstens heiko.carst
2012/9/26 Ingo Molnar mi...@kernel.org:
* Frederic Weisbecker fweis...@gmail.com wrote:
+ return -1
this bit wasn't very well tested. I applied it with the obvious
fix, lets hope it holds up in testing.
Ouch. Bad indeed. I booted with x86-64 but forgot to try x86-32.
Sorry
2012/9/25 Paul E. McKenney paul...@linux.vnet.ibm.com:
On Tue, Sep 25, 2012 at 01:59:26PM +0200, Frederic Weisbecker wrote:
Given that we have:
rcu_irq_enter()
rcu_user_exit()
rcu_user_enter()
rcu_irq_exit()
Indeed, the code to deal with irq misnestings won't like that at all
2012/9/25 Sasha Levin levinsasha...@gmail.com:
On 09/25/2012 02:06 PM, Frederic Weisbecker wrote:
Sasha, sorry to burden you with more testing request.
Could you please try out this new branch? It includes some fixes after Wu
Fenguang and
Dan Carpenter reports (not related to your warnings
On Tue, Sep 25, 2012 at 11:36:54AM -0700, Paul E. McKenney wrote:
On Tue, Sep 25, 2012 at 08:28:23PM +0200, Sasha Levin wrote:
On 09/25/2012 02:06 PM, Frederic Weisbecker wrote:
Sasha, sorry to burden you with more testing request.
Could you please try out this new branch? It includes
2012/9/25 Michael Neuling mi...@neuling.org:
Michael Neuling mi...@neuling.org wrote:
Frederic Weisbecker fweis...@gmail.com wrote:
On Thu, Aug 16, 2012 at 02:23:54PM +1000, Michael Neuling wrote:
Hi,
I've been trying to get hardware breakpoints with perf to work on POWER7
On Tue, Sep 25, 2012 at 01:57:26PM +0900, Namhyung Kim wrote:
Ping. Any comments for this?
Arun, thanks for testing!
Namhyung
When Arun was working on this, I asked him to explore if it could make sense to
reuse
the -b, --branch-stack perf report option. Because after all, this feature
On Wed, Oct 03, 2012 at 02:29:47PM +0200, Jiri Olsa wrote:
+#ifdef CONFIG_X86_64
+__weak void
Only annotate with __weak the default implementation you want to be
overriden. Here you want it to actually override the default __weak version.
+arch_sample_regs_user_fixup(struct perf_regs_user
Morton a...@linux-foundation.org
CC: Frederic Weisbecker fweis...@gmail.com
Signed-off-by: Kees Cook keesc...@chromium.org
---
This is the first of a series of 202 patches removing EXPERIMENTAL
from
all the Kconfigs in the tree. Should I send them all to lkml
It's only there to call rcu_user_hooks_switch(). Let's
just call rcu_user_hooks_switch() directly, we don't need this
function in the middle.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Josh Triplett j...@joshtriplett.org
Cc: Peter Zijlstra pet...@infradead.org
---
include/linux
On Wed, Oct 03, 2012 at 11:39:45AM -0700, Paul E. McKenney wrote:
On Wed, Oct 03, 2012 at 08:21:52PM +0200, Frederic Weisbecker wrote:
It's only there to call rcu_user_hooks_switch(). Let's
just call rcu_user_hooks_switch() directly, we don't need this
function in the middle.
Hello
On Wed, Oct 03, 2012 at 11:43:32AM -0700, Kees Cook wrote:
I would expect a simple addition of this is dangerous/buggy to the
description and default n is likely the way to go for that kind of
thing.
Agreed.
I think the history of CONFIG_EXPERIMENTAL has proven there
isn't a sensible way to
On Wed, Oct 03, 2012 at 03:36:53PM -0400, Dave Jones wrote:
On Wed, Oct 03, 2012 at 07:46:18PM +0200, Frederic Weisbecker wrote:
it in the kernel tree, unless we wanted people to use the option?
A solution could be to add that option under CONFIG_DEBUG_KERNEL and
specify
On Thu, Oct 04, 2012 at 10:43:03AM +0900, Namhyung Kim wrote:
Hi Frederic,
On Tue, 2 Oct 2012 17:54:10 +0200, Frederic Weisbecker wrote:
On Wed, Oct 03, 2012 at 12:21:32AM +0900, Namhyung Kim wrote:
The '_get_comp_words_by_ref' function is available from the bash
completion v1.2 so
also
need to enable:
- CONFIG_EVENT_TRACING and CONFIG_RCU_TRACE
And you also need this boot parameter:
- trace_event=rcu_dyntick
Thanks a lot!
---
From 824f2ef855597d6dd263bb363727e4585db88ca3 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker fweis...@gmail.com
Date: Thu, 4 Oct 2012 17:30:36
On Thu, Oct 04, 2012 at 03:08:33PM -0300, Arnaldo Carvalho de Melo wrote:
From: Namhyung Kim namhyung@lge.com
Currently tracepoint events cannot be completed because they contain a
colon (:) character. The colon is considered as a word separator when
bash completion is done - variable
2012/10/5 Paul E. McKenney paul...@linux.vnet.ibm.com:
On Thu, Oct 04, 2012 at 07:31:50AM -0700, Paul E. McKenney wrote:
On Thu, Oct 04, 2012 at 02:55:39AM +0100, Matthew Garrett wrote:
On Wed, Oct 03, 2012 at 01:03:14PM -0700, Paul E. McKenney wrote:
That has not proven sufficient for me
this up from RCU into this new level of indirection
because this tracking is also going to be used to implement an on
demand generic virtual cputime accounting. A necessary step to
shutdown the tick while still accounting the cputime.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Andrew
native
virtual based cputime accounting which hooks on low level code and use
a cpu hardware clock. Precision is not the goal of this though.
- There is probably more overhead than a native virtual based cputime
accounting. But this relies on hooks that are already set anyway.
Signed-off-by: Frederic
/linux-dynticks.git
vtime/generic-v4
Frederic Weisbecker (3):
context_tracking: New context tracking susbsystem
cputime: Allow dynamic switch between tick/virtual based cputime
accounting
cputime: Generic on-demand virtual cputime accounting
arch/Kconfig
anytime in order to minimize the
overhead associated to user hooks.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Andrew Morton a...@linux-foundation.org
Cc: H. Peter Anvin h...@zytor.com
Cc: Ingo Molnar mi...@kernel.org
Cc: Paul E. McKenney paul...@linux.vnet.ibm.com
Cc: Peter Zijlstra pet
2012/11/2 Christoph Lameter c...@linux.com:
Also could we have this support without cpusets? There are multiple means
to do system segmentation (f.e. cgroups) and something like hz control is
pretty basic. Control via some cpumask like irq affinities in f.e.
2012/11/5 Christoph Lameter c...@linux.com:
On Fri, 2 Nov 2012, Paul E. McKenney wrote:
On Fri, Nov 02, 2012 at 04:51:50PM -0400, Steven Rostedt wrote:
On Fri, 2012-11-02 at 13:41 -0700, Paul E. McKenney wrote:
The no-CBs mask would be read-only for some time -- changed only at
boot.
2012/10/29 Steven Rostedt rost...@goodmis.org:
On Mon, 2012-10-29 at 14:28 +0100, Frederic Weisbecker wrote:
On irq work initialization, let the user choose to define it
as lazy or not. Lazy means that we don't want to send
an IPI (provided the arch can anyway) when we enqueue this
work
ordering.
Changelog-heavily-inspired-by: Steven Rostedt rost...@goodmis.org
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt
for non-urgent enqueuers
(like printk in the future) that may prefer not to raise
an IPI storm in case of frequent enqueuing on short periods
of time.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar
-dynticks.git
nohz/printk-v4
Thanks.
Frederic Weisbecker (7):
irq_work: Fix racy IRQ_WORK_BUSY flag setting
irq_work: Fix racy check on work pending flag
irq_work: Remove CONFIG_HAVE_IRQ_WORK
nohz: Add API to check tick state
irq_work: Don't stop the tick with pending works
irq_work
irq work can run on any arch even without IPI
support because of the hook on update_process_times().
So lets remove HAVE_IRQ_WORK because it doesn't reflect
any backend requirement.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner
the printk tick using a lazy irq work.
This subsystem takes care of the timer tick state and can
fix up accordingly.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton
Don't stop the tick if we have pending irq works on the
queue, otherwise if the arch can't raise self-IPIs, we may not
find an opportunity to execute the pending works for a while.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t
We need some quick way to check if the CPU has stopped
its tick. This will be useful to implement the printk tick
using the irq work subsystem.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi
the value we wish to be
in the work-flags but we only make any conclusion after the value
returned by the cmpxchg() call that either claims the work or let
the current owner handle the pending work for us.
Changelog-heavily-inspired-by: Steven Rostedt rost...@goodmis.org
Signed-off-by: Frederic
2012/10/12 Frederic Weisbecker fweis...@gmail.com:
Hi,
So here is a proposition on what we can do to make printk
correctly working on a tickless CPU.
Although it's targeted to be part of the adaptive tickmess
implemetation, it's pretty standalone and generic and also
works for printk
2012/10/19 Tejun Heo t...@kernel.org:
On Fri, Oct 19, 2012 at 09:35:26AM -0400, Frederic Weisbecker wrote:
2012/10/18 Tejun Heo t...@kernel.org:
From d935a5d6832a264ce52f4257e176f4f96cbaf048 Mon Sep 17 00:00:00 2001
From: Tejun Heo t...@kernel.org
Date: Thu, 18 Oct 2012 17:40:30 -0700
Most of the time, x86 can trigger self-IPIs. Tell
irq work subsystem about it.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc
We need some quick way to check if the CPU has stopped
its tick. This will be useful to implement the printk tick
using the irq work subsystem.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi
irq work is supposed to work everywhere because of the irq work
hook in the generic timer tick function.
I might be missing something though...
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi
the printk tick using irq work.
This subsystem takes care of the timer tick state and can
fix up accordingly.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton
If we enqueue a work while in dyntick idle mode and the arch doesn't
have self-IPI support, we may not find an opportunity to run the work
before a while.
In this case, exit the idle loop to re-evaluate irq_work_needs_cpu()
and restart the tick.
Signed-off-by: Frederic Weisbecker fweis
to avoid IPI storm
when we have lots of enqueuing of non-urgent works like klogd wakeup
in short period of time so this keeps the old printk_tick behaviour.
It also teaches irq_work to handle nohz mode.
Warning: only compile tested in x86 for now.
Frederic Weisbecker (8):
irq_work: Move
periods of
time.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt rost...@goodmis.org
Cc: Paul Gortmaker paul.gortma
This prepares us to make printk working on nohz CPUs
using irq work.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt
This optimization doesn't matter much. But this prepares the
arch headers that we need to add a new API in order to detect
when the arch can trigger self IPIs to implement the irq work.
This is necessary later to make printk working in nohz CPUs.
Signed-off-by: Frederic Weisbecker fweis
2012/10/20 Joe Perches j...@perches.com:
On Sat, 2012-10-20 at 12:22 -0400, Frederic Weisbecker wrote:
lets implement the printk tick using irq work.
Hi Frederic.
Can you redo this change please against -next in a few days?
Andrew Morton picked up this series,
https://lkml.org/lkml/2012
2012/10/19 Tejun Heo t...@kernel.org:
Hello, Frederic.
On Fri, Oct 19, 2012 at 03:44:20PM -0400, Frederic Weisbecker wrote:
For -stable, I think it's better to revert. If you want to remove
task_lock, let's do it for 3.8.
I don't think that a wrong comment justifies a patch to stable
2012/10/20 Frederic Weisbecker fweis...@gmail.com:
2012/10/19 Tejun Heo t...@kernel.org:
Hello, Frederic.
On Fri, Oct 19, 2012 at 03:44:20PM -0400, Frederic Weisbecker wrote:
For -stable, I think it's better to revert. If you want to remove
task_lock, let's do it for 3.8.
I don't think
2012/10/21 Tejun Heo t...@kernel.org:
Hello, Frederic.
On Sat, Oct 20, 2012 at 02:21:43PM -0400, Frederic Weisbecker wrote:
CPU 0
CPU 1
cgroup_task_migrate {
task_lock(p)
rcu_assign_pointer(tsk-cgroups, newcg);
task_unlock(tsk
2012/10/22 Peter Zijlstra pet...@infradead.org:
On Sat, 2012-10-20 at 12:22 -0400, Frederic Weisbecker wrote:
+ if (empty) {
+ /*
+* If an IPI is requested, raise it right away. Otherwise
wait
+* for the next tick unless it's stopped. Now
for no good reason. vtime_account_system() OTOH is a no-op in
this config option.
A further optimization may consist in introducing a vtime_account_guest()
that directly calls account_guest_time().
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu
accounting
as well in the future.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
---
include/linux/hardirq.h | 82 +++
include/linux
.
That, for sure, will inspire for even more cputime optimizations/cleanups.
Thanks.
PS: tested on x86 and ppc64 (checked reliability of times and /proc/stat).
But only built tested on s390 and ia64.
Frederic Weisbecker (3):
kvm: Directly account vtime to system on guest switch
cputime
*()
this call is pointless to CONFIG_IRQ_TIME_ACCOUNTING.
To fix the confusion, change vtime_account() to irqtime_account_irq()
in CONFIG_IRQ_TIME_ACCOUNTING. This way we ensure future account_vtime()
calls won't waste useless cycles in the irqtime APIs.
Signed-off-by: Frederic Weisbecker fweis
It's only there to call rcu_user_hooks_switch(). Let's
just call rcu_user_hooks_switch() directly, we don't need this
function in the middle.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Josh Triplett j...@joshtriplett.org
Cc: Peter Zijlstra pet...@infradead.org
Cc: Richard
Discourage distros from enabling CONFIG_RCU_USER_QS
because it brings overhead for no benefits yet.
It's not a useful feature on its own until we can
fully run an adaptive tickless kernel.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
---
init/Kconfig | 12
1 files
This optimization doesn't matter much. But this prepares the
arch headers that we need to add a new API in order to detect
when the arch hooks on the tick to implement the irq work.
This is necessary later to make printk working in nohz CPUs.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Most of the time, x86 can trigger self-IPIs. Tell
irq work subsystem about it.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc
this when
the tick is stopped only.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt rost...@goodmis.org
---
kernel
It may optimize a bit the tick path for archs that have their
own way to run irq work.
This may be further optimized using static keys.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi
for your comments.
Thanks.
PS: only built-tested for now.
Frederic Weisbecker (5):
irq_work: Move irq_work_raise() declaration/default definition to
arch headers
irq_work: Only run irq_work from tick if arch needs it
x86: Implement arch_irq_work_use_tick
nohz: Add API to check tick
We need some quick way to check if the CPU has stopped
its tick. This will be useful for printk when it wants
to wake up klogd on nohz CPU.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi
First of all, thanks a lot for your report.
2012/10/24 Sergey Senozhatsky sergey.senozhat...@gmail.com:
On (10/24/12 20:06), Oleg Nesterov wrote:
On 10/24, Sergey Senozhatsky wrote:
small question,
ptrace_notify() and forward calls are able to both indirectly and directly
call
These APIs are scattered around and are going to expand a bit.
Let's create a dedicated header file for sanity.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar mi...@kernel.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Steven Rostedt
vtime_account_system().
CONFIG_IRQ_TIME_ACCOUNTING behaviour doesn't change and directly
maps to its own vtime_account() implementation. One may want
to take benefits from the new APIs to optimize irq time accounting
as well in the future.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet
consist in introducing a vtime_account_guest()
that directly calls account_guest_time().
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Tony Luck tony.l...@intel.com
Cc: Fenghua Yu fenghua...@intel.com
Cc: Benjamin Herrenschmidt b...@kernel.crashing.org
Cc: Paul Mackerras pau
and x86. Built tested on ia64. s390 doesn't build defconfig
on v3.7-rc2.
Frederic Weisbecker (5):
vtime: Gather vtime declarations to their own header file
vtime: Provide an irq safe version of vtime_account_system()
kvm: Directly account vtime to system on guest switch
cputime: Specialize irq
*()
this call is pointless to CONFIG_IRQ_TIME_ACCOUNTING.
To fix the confusion, change vtime_account() to irqtime_account_irq()
in CONFIG_IRQ_TIME_ACCOUNTING. This way we ensure future account_vtime()
calls won't waste useless cycles in the irqtime APIs.
Signed-off-by: Frederic Weisbecker fweis
vtime_account_system() currently has only one caller with
vtime_account() that is irq safe.
Now we are going to call it from other places like kvm, so
let's provide an irqsafe version.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Ingo Molnar
2012/10/25 Sergey Senozhatsky sergey.senozhat...@gmail.com:
On (10/25/12 00:32), Frederic Weisbecker wrote:
First of all, thanks a lot for your report.
2012/10/24 Sergey Senozhatsky sergey.senozhat...@gmail.com:
On (10/24/12 20:06), Oleg Nesterov wrote:
On 10/24, Sergey Senozhatsky wrote
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