Messages in this thread Patch in this message | | | Date | Tue, 15 Mar 2016 10:53:37 +0100 | From | Ingo Molnar <> | Subject | [PATCH] nohz: Change tick_dep_mask from 'unsigned long' to 'unsigned int' |
| |
Linus noticed that the new tick_dep_mask types introduced in:
d027d45d8a17 ("nohz: New tick dependency mask")
... are sloppily defined as 'unsigned long' - which is wasteful to carry just 4 bits and which may also create suboptimal data types on 64-bit systems with word alignment padding holes in them.
Fix this by changing the type to the more natural 'unsigned int'.
(The xchg_or() API will work fine with 'unsigned int' as well.)
Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> --- include/linux/sched.h | 4 ++-- kernel/time/tick-sched.c | 11 +++++------ 2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index c617ea12c6b7..6d1842bb7abd 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -718,7 +718,7 @@ struct signal_struct { struct task_cputime cputime_expires; #ifdef CONFIG_NO_HZ_FULL - unsigned long tick_dep_mask; + unsigned int tick_dep_mask; #endif struct list_head cpu_timers[3]; @@ -1548,7 +1548,7 @@ struct task_struct { #endif #ifdef CONFIG_NO_HZ_FULL - unsigned long tick_dep_mask; + unsigned int tick_dep_mask; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ u64 start_time; /* monotonic time in nsec */ diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 851631899352..fe0f57f3432f 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -157,9 +157,9 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) cpumask_var_t tick_nohz_full_mask; cpumask_var_t housekeeping_mask; bool tick_nohz_full_running; -static unsigned long tick_dep_mask; +static unsigned int tick_dep_mask; -static void trace_tick_dependency(unsigned long dep) +static void trace_tick_dependency(unsigned int dep) { if (dep & TICK_DEP_MASK_POSIX_TIMER) { trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER); @@ -259,10 +259,9 @@ static void tick_nohz_full_kick_all(void) preempt_enable(); } -static void tick_nohz_dep_set_all(unsigned long *dep, - enum tick_dep_bits bit) +static void tick_nohz_dep_set_all(unsigned int *dep, enum tick_dep_bits bit) { - unsigned long prev; + unsigned int prev; prev = xchg_or(dep, BIT_MASK(bit)); if (!prev) @@ -289,7 +288,7 @@ void tick_nohz_dep_clear(enum tick_dep_bits bit) */ void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit) { - unsigned long prev; + unsigned int prev; struct tick_sched *ts; ts = per_cpu_ptr(&tick_cpu_sched, cpu);
| |