I wanted to ping the patch below again, since I haven't heard any feedback.
I note that Rik van Riel's change posted this weekend offers similar functionality for userspace. My change offers a convenient API for, e.g., kernel drivers setting up default irq balancing. https://lkml.org/lkml/2015/3/28/94 Although it would be possible to do the same thing by iterating over the existing tick_nohz_full_cpu() API, that seems kind of silly. An alternate API would be one that just returned the full no_hz cpumask to kernel callers; I'd be happy with that as well, but my instinct was to make the API as narrow as possible to start with. Comments? On 03/24/2015 03:21 PM, cmetc...@ezchip.com wrote:
From: Chris Metcalf <cmetc...@ezchip.com> This is useful, for example, to modify a cpumask to avoid the nohz cores so that interrupts aren't sent to them. Signed-off-by: Chris Metcalf <cmetc...@ezchip.com> --- Motivated by patch 4/4 in this series. include/linux/tick.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 9c085dc12ae9..d53ad4892a39 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -186,6 +186,12 @@ static inline bool tick_nohz_full_cpu(int cpu) return cpumask_test_cpu(cpu, tick_nohz_full_mask); }+static inline void tick_nohz_full_clear_cpus(struct cpumask *mask)+{ + if (tick_nohz_full_enabled()) + cpumask_andnot(mask, mask, tick_nohz_full_mask); +} + extern void __tick_nohz_full_check(void); extern void tick_nohz_full_kick(void); extern void tick_nohz_full_kick_cpu(int cpu); @@ -194,6 +200,7 @@ extern void __tick_nohz_task_switch(struct task_struct *tsk); #else static inline bool tick_nohz_full_enabled(void) { return false; } static inline bool tick_nohz_full_cpu(int cpu) { return false; } +static inline void tick_nohz_full_clear_cpus(struct cpumask *mask) { } static inline void __tick_nohz_full_check(void) { } static inline void tick_nohz_full_kick_cpu(int cpu) { } static inline void tick_nohz_full_kick(void) { }
-- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
