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/sgi-ip27 | |
| 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/sgi-ip27')
| -rw-r--r-- | arch/mips/sgi-ip27/ip27-irq.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c index 3fbaef97a1b8..16ec4e12daa3 100644 --- a/arch/mips/sgi-ip27/ip27-irq.c +++ b/arch/mips/sgi-ip27/ip27-irq.c @@ -107,10 +107,14 @@ static void ip27_do_irq_mask0(void) scheduler_ipi(); } else if (pend0 & (1UL << CPU_CALL_A_IRQ)) { LOCAL_HUB_CLR_INTR(CPU_CALL_A_IRQ); - smp_call_function_interrupt(); + irq_enter(); + generic_smp_call_function_interrupt(); + irq_exit(); } else if (pend0 & (1UL << CPU_CALL_B_IRQ)) { LOCAL_HUB_CLR_INTR(CPU_CALL_B_IRQ); - smp_call_function_interrupt(); + irq_enter(); + generic_smp_call_function_interrupt(); + irq_exit(); } else #endif { |