diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2019-02-08 14:48:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-05 22:29:12 +0200 |
| commit | acb5aefd789bd138c5a0616581efe0ccf1087781 (patch) | |
| tree | afd4ad8e32be1da57d841fbceab0f4efb3e270bd /include/linux/irqdesc.h | |
| parent | e940258c4e886022e698815274bccc43dd5cc87b (diff) | |
genirq: Avoid summation loops for /proc/stat
[ Upstream commit 1136b0728969901a091f0471968b2b76ed14d9ad ]
Waiman reported that on large systems with a large amount of interrupts the
readout of /proc/stat takes a long time to sum up the interrupt
statistics. In principle this is not a problem. but for unknown reasons
some enterprise quality software reads /proc/stat with a high frequency.
The reason for this is that interrupt statistics are accounted per cpu. So
the /proc/stat logic has to sum up the interrupt stats for each interrupt.
This can be largely avoided for interrupts which are not marked as
'PER_CPU' interrupts by simply adding a per interrupt summation counter
which is incremented along with the per interrupt per cpu counter.
The PER_CPU interrupts need to avoid that and use only per cpu accounting
because they share the interrupt number and the interrupt descriptor and
concurrent updates would conflict or require unwanted synchronization.
Reported-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/20190208135020.925487496@linutronix.de
8<-------------
v2: Undo the unintentional layout change of struct irq_desc.
include/linux/irqdesc.h | 1 +
kernel/irq/chip.c | 12 ++++++++++--
kernel/irq/internals.h | 8 +++++++-
kernel/irq/irqdesc.c | 7 ++++++-
4 files changed, 24 insertions(+), 4 deletions(-)
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux/irqdesc.h')
| -rw-r--r-- | include/linux/irqdesc.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index c9be57931b58..bb5547a83daf 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -61,6 +61,7 @@ struct irq_desc { unsigned int core_internal_state__do_not_mess_with_it; unsigned int depth; /* nested irq disables */ unsigned int wake_depth; /* nested wake enables */ + unsigned int tot_count; unsigned int irq_count; /* For detecting broken IRQs */ unsigned long last_unhandled; /* Aging timer for unhandled count */ unsigned int irqs_unhandled; |