linux.git/kernel/softirq.c, branch v2.6.22-rc4

Add suspend-related notifications for CPU hotplug

2007-05-09T19:30:56+00:00

Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki 
Cc: Gautham R Shenoy 
Cc: Pavel Machek 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] tick-management: dyntick / highres functionality

2007-02-16T16:13:59+00:00

With Ingo Molnar 

Add functions to provide dynamic ticks and high resolution timers.  The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks.  The dyntick
functionality can be disabled on the kernel commandline.  Provide also the
infrastructure to support high resolution timers.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Cc: john stultz 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] uninline irq_enter()

2007-02-16T16:13:58+00:00

Uninline irq_enter().  [dynticks adds more stuff to it]

No functional changes.

Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner 
Cc: john stultz 
Cc: Roman Zippel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] softirq: remove BUG_ONs which can incorrectly trigger

2006-12-07T16:39:43+00:00

It is possible to have tasklets get scheduled before softirqd has had a chance
to spawn on all CPUs.  This is totally harmless; after success during action
CPU_UP_PREPARE, action CPU_ONLINE will be called, which immediately wakes
softirqd on the appropriate CPU to process the already pending tasklets.  So
there is no danger of having a missed wakeup for any tasklets that were
already pending.

In particular, i386 is affected by this during startup, and is visible when
using a very large initrd; during the time it takes for the initrd to be
decompressed, a timer IRQ can come in and schedule RCU callbacks.  It is also
possible that resending of a hardware IRQ via a softirq triggers the same bug.

Because of different timing conditions, this shows up in all emulators and
virtual machines tested, including Xen, VMware, Virtual PC, and Qemu.  It is
also possible to trigger on native hardware with a large enough initrd,
although I don't have a reliable case demonstrating that.

Signed-off-by: Zachary Amsden 
Cc: 
Cc: Ingo Molnar 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] check return value of cpu_callback

2006-09-29T16:18:14+00:00

Spawing ksoftirqd, migration, or watchdog, and calling init_timers_cpu()
may fail with small memory.  If it happens in initcalls, kernel NULL
pointer dereference happens later.  This patch makes crash happen
immediately in such cases.  It seems a bit better than getting kernel NULL
pointer dereference later.

Cc: Ingo Molnar 
Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Reducing local_bh_enable/disable overhead in irqtrace

2006-07-31T20:28:42+00:00

The recent changes from irqtrace feature has added overheads to
local_bh_disable and local_bh_enable that reduces UDP performance across
x86_64 and IA64, even though IA64 does not support the irqtrace feature.
Patch in question is

[PATCH]lockdep: irqtrace subsystem, core
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=c
ommit;h=de30a2b355ea85350ca2f58f3b9bf4e5bc007986

Prior to this patch, local_bh_disable was a short macro.  Now it is a
function which calls __local_bh_disable with added irq flags save and
restore.  The irq flags save and restore were also added to
local_bh_enable, probably for injecting the trace irqs code.

This overhead is on the generic code path across all architectures.  On a
IA_64 test machine (Itanium-2 1.6 GHz) running a benchmark like netperf's
UDP streaming test, the added overhead results in a drop of 3% in
throughput, as udp_sendmsg calls the local_bh_enable/disable several times.

Other workloads that have heavy usages of local_bh_enable/disable could
also be affected.  The patch ideally should not have affected IA-64
performance as it does not have IRQ tracing support.  A significant portion
of the overhead is in the added irq flags save and restore, which I think
is not needed if IRQ tracing is unused.  A suggested patch is attached
below that recovers the lost performance.  However, the "ifdef"s in the
patch are a bit ugly.

Signed-off-by: Tim Chen 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] cpu hotplug: replace devinit* with cpuinit* for cpu notifications

2006-07-31T20:28:39+00:00

Few of the callback functions and notifier blocks that are associated with cpu
notifications incorrectly have __devinit and __devinitdata.  They should be
__cpuinit and __cpuinitdata instead.

It makes no functional difference but wastes text area when CONFIG_HOTPLUG is
enabled and CONFIG_HOTPLUG_CPU is not.

This patch fixes all those instances.

Signed-off-by: Chandra Seetharaman 
Cc: Ashok Raj 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] unexport open_softirq

2006-07-15T04:53:53+00:00

Christoph Hellwig:
open_softirq just enables a softirq.  The softirq array is statically
allocated so to add a new one you would have to patch the kernel.  So
there's no point to keep this export at all as any user would have to
patch the enum in include/linux/interrupt.h anyway.

Signed-off-by: Adrian Bunk 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] kernel/softirq.c: EXPORT_UNUSED_SYMBOL

2006-07-10T20:24:18+00:00

This patch marks an unused export as EXPORT_UNUSED_SYMBOL.

Signed-off-by: Adrian Bunk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] lockdep: irqtrace subsystem, move account_system_vtime() calls into kernel/softirq.c

2006-07-03T22:27:10+00:00

At the moment, powerpc and s390 have their own versions of do_softirq which
include local_bh_disable() and __local_bh_enable() calls.  They end up
calling __do_softirq (in kernel/softirq.c) which also does
local_bh_disable/enable.

Apparently the two levels of disable/enable trigger a warning from some
validation code that Ingo is working on, and he would like to see the outer
level removed.  But to do that, we have to move the account_system_vtime
calls that are currently in the arch do_softirq() implementations for
powerpc and s390 into the generic __do_softirq() (this is a no-op for other
archs because account_system_vtime is defined to be an empty inline
function on all other archs).  This patch does that.

Signed-off-by: Paul Mackerras 
Signed-off-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds