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This allows the later-panicking tiles to wait in a lower power state
until they get interrupted with an smp_send_stop().
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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This avoids the hardware istream prefetcher doing unnecessary work.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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We have lots of infrastructure in place to partition multi-core systems
such that we have a group of CPUs that are dedicated to specific task:
cgroups, scheduler and interrupt affinity, and cpuisol= boot parameter.
Still, kernel code will at times interrupt all CPUs in the system via IPIs
for various needs. These IPIs are useful and cannot be avoided
altogether, but in certain cases it is possible to interrupt only specific
CPUs that have useful work to do and not the entire system.
This patch set, inspired by discussions with Peter Zijlstra and Frederic
Weisbecker when testing the nohz task patch set, is a first stab at trying
to explore doing this by locating the places where such global IPI calls
are being made and turning the global IPI into an IPI for a specific group
of CPUs. The purpose of the patch set is to get feedback if this is the
right way to go for dealing with this issue and indeed, if the issue is
even worth dealing with at all. Based on the feedback from this patch set
I plan to offer further patches that address similar issue in other code
paths.
This patch creates an on_each_cpu_mask() and on_each_cpu_cond()
infrastructure API (the former derived from existing arch specific
versions in Tile and Arm) and uses them to turn several global IPI
invocation to per CPU group invocations.
Core kernel:
on_each_cpu_mask() calls a function on processors specified by cpumask,
which may or may not include the local processor.
You must not call this function with disabled interrupts or from a
hardware interrupt handler or from a bottom half handler.
arch/arm:
Note that the generic version is a little different then the Arm one:
1. It has the mask as first parameter
2. It calls the function on the calling CPU with interrupts disabled,
but this should be OK since the function is called on the other CPUs
with interrupts disabled anyway.
arch/tile:
The API is the same as the tile private one, but the generic version
also calls the function on the with interrupts disabled in UP case
This is OK since the function is called on the other CPUs
with interrupts disabled.
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Michal Nazarewicz <mina86@mina86.org>
Cc: Kosaki Motohiro <kosaki.motohiro@gmail.com>
Cc: Milton Miller <miltonm@bga.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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For future rework of try_to_wake_up() we'd like to push part of that
function onto the CPU the task is actually going to run on.
In order to do so we need a generic callback from the existing scheduler IPI.
This patch introduces such a generic callback: scheduler_ipi() and
implements it as a NOP.
BenH notes: PowerPC might use this IPI on offline CPUs under rare conditions!
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110405152728.744338123@chello.nl
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Previously we assumed this was impossible, but in fact it can happen.
Handle it gracefully by retrying after issuing a warning.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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This completes the tile migration to the new naming scheme for
the architecture-specific irq management code.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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While not a port to KVM (yet), this change modifies the kernel
to be able to build either at PL1 or at PL2 with a suitable
config switch. Pushing up this change avoids handling branch
merge issues going forward with the KVM work.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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This model is based on the on-chip interrupt model used by the
TILE-Gx next-generation hardware, and interacts much more cleanly
with the Linux generic IRQ layer.
The change includes modifications to the Tilera hypervisor, which
are reflected in the hypervisor headers in arch/tile/include/arch/.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
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This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.
This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>
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