diff options
| author | Alex Smith <alex.smith@imgtec.com> | 2015-07-24 16:57:49 +0100 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2015-08-03 09:25:12 +0200 |
| commit | 4ace6139bf23ab4f152ba4207fc10b76cc01d2a5 (patch) | |
| tree | 8a4682b3460ebd05961e402bc1bb353b74ec97ff /arch/mips/sibyte/bcm1480 | |
| parent | 55fdcb2d56b6edc027657fde9da0c4f224d32303 (diff) | |
MIPS: SMP: Don't increment irq_count multiple times for call function IPIs
The majority of SMP platforms handle their IPIs through do_IRQ()
which calls irq_{enter/exit}(). When a call function IPI is received,
smp_call_function_interrupt() is called which also calls
irq_{enter,exit}(), meaning irq_count is raised twice.
When tick broadcasting is used (which is implemented via a call
function IPI), this incorrectly causes all CPU idle time on the core
receiving broadcast ticks to be accounted as time spent servicing
IRQs, as account_process_tick() will account as such if irq_count is
greater than 1. This results in 100% CPU usage being reported on a
core which receives its ticks via broadcast.
This patch removes the SMP smp_call_function_interrupt() wrapper which
calls irq_{enter,exit}(). Platforms which handle their IPIs through
do_IRQ() now call generic_smp_call_function_interrupt() directly to
avoid incrementing irq_count a second time. Platforms which don't
(loongson, sgi-ip27, sibyte) call generic_smp_call_function_interrupt()
wrapped in irq_{enter,exit}().
Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10770/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/sibyte/bcm1480')
| -rw-r--r-- | arch/mips/sibyte/bcm1480/smp.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/arch/mips/sibyte/bcm1480/smp.c b/arch/mips/sibyte/bcm1480/smp.c index af7d44edd9a8..4c71aea25663 100644 --- a/arch/mips/sibyte/bcm1480/smp.c +++ b/arch/mips/sibyte/bcm1480/smp.c @@ -29,8 +29,6 @@ #include <asm/sibyte/bcm1480_regs.h> #include <asm/sibyte/bcm1480_int.h> -extern void smp_call_function_interrupt(void); - /* * These are routines for dealing with the bcm1480 smp capabilities * independent of board/firmware @@ -184,6 +182,9 @@ void bcm1480_mailbox_interrupt(void) if (action & SMP_RESCHEDULE_YOURSELF) scheduler_ipi(); - if (action & SMP_CALL_FUNCTION) - smp_call_function_interrupt(); + if (action & SMP_CALL_FUNCTION) { + irq_enter(); + generic_smp_call_function_interrupt(); + irq_exit(); + } } |