PM QoS and other idle frameworks can do a better job of addressing power
and performance requirements for a cpu, knowing the IRQs that are
affine to that cpu. If a performance request is placed against serving
the IRQ faster and if the IRQ is affine to a set of cpus, then setting
the performance requirements only on those cpus help save power on the
rest of the cpus. PM QoS framework is one such framework interested in
knowing the smp_affinity of an IRQ and the change notificiation in this
regard. QoS requests for the CPU_DMA_LATENCY constraint currently apply
to all cpus, but when attached to an IRQ, can be applied only to the set
of cpus that IRQ's smp_affinity is set to. This allows other cpus to
enter deeper sleep states to save power. More than one framework/driver
can be interested in such information.
The current implementation allows only a single notification callback
whenever the IRQ's SMP affinity is changed. Adding a second notification
punts the existing notifier function out of registration. Add a list of
notifiers, allowing multiple clients to register for irq affinity
notifications.
The kref object associated with the struct irq_affinity_notify was used
to prevent the notifier object from being released if there is a pending
notification. It was incremented before the work item was scheduled and
was decremented when the notification was completed. If the kref count
was zero at the end of it, the release function gets a callback allowing
the module to release the irq_affinity_notify memory. This works well
for a single notification. When multiple clients are registered, no
single kref object can be used. Hence, the work function when scheduled,
will increase the kref count using the kref_get_unless_zero(), so if the
module had already unregistered the irq_affinity_notify object while the
work function was scheduled, it will not be notified.
Change-Id: If2e38ce8d7c43459ba1604d5b4798d1bad966997
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Patch-mainline: linux-pm @ Wed, 27 Aug 2014 13:18:28
https://lkml.org/lkml/2014/8/27/609
[mnalajal@codeaurora.org: resolve NON SMP target compilation issues]
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>
After the last architecture switched to generic hard irqs the config
options HAVE_GENERIC_HARDIRQS & GENERIC_HARDIRQS and the related code
for !CONFIG_GENERIC_HARDIRQS can be removed.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Git-commit: 0244ad004a54e39308d495fee0a2e637f8b5c317
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[imaund@codeaurora.org: resolve merge conflicts]
Signed-off-by: Ian Maund <imaund@codeaurora.org>
In some cases, free_irq_cpu_rmap() is called while holding a lock (eg
rtnl). This can lead to deadlocks, because it invokes
flush_scheduled_work() which ends up waiting for whole system workqueue
to flush, but some pending works might try to acquire the lock we are
already holding.
This commit uses reference-counting to replace
irq_run_affinity_notifiers(). It also removes
irq_run_affinity_notifiers() altogether.
[akpm@linux-foundation.org: eliminate free_cpu_rmap, rename cpu_rmap_reclaim() to cpu_rmap_release(), propagate kref_put() retval from cpu_rmap_put()]
Signed-off-by: David Decotigny <decot@googlers.com>
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU. This requires a reverse-map of IRQ affinity. Add
library functions to support a generic reverse-mapping from CPUs to
objects with affinity and the specific case where the objects are
IRQs.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Lina Iyer
Martin Schwidefsky
David Decotigny
Paul Gortmaker
Ben Hutchings