Dear RT folks!
I'm pleased to announce the v3.18.13-rt9 patch set.
Changes since v3.18.13-rt8
- arm64 support. Patches by Anders Roxell.
- fix for XFS live-stall by Steven Rostedt.
- kvm mpic emulation for e500 (PPC) CPUs disabled. It is now known not
to work perfectly. It is been worked on a final (workin) solution.
Patch sent by Bogdan Purcareata.
- A dead lock fix for ftrace noticed and fixed by Jan Kiszka.
Known issues:
- bcache is disabled.
- CPU hotplug works in general. Steven's test script however
deadlocks usually on the second invocation.
- xor / raid_pq
I had max latency jumping up to 67563us on one CPU while the next
lower max was 58us. I tracked it down to module's init code of
xor and raid_pq. Both disable preemption while measuring the
performance of the individual implementation.
The delta patch against 3.18.13-rt8 is appended below and can be found here:
https://www.kernel.org/pub/linux/kernel/projects/rt/3.18/incr/patch-3.18.13-rt8-rt9.patch.xz
The RT patch against 3.18.13 can be found here:
https://www.kernel.org/pub/linux/kernel/projects/rt/3.18/patch-3.18.13-rt9.patch.xz
The split quilt queue is available at:
https://www.kernel.org/pub/linux/kernel/projects/rt/3.18/patches-3.18.13-rt9.tar.xz
Sebastian
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index dc2d66cdf311..54ec128acf2d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -59,8 +59,10 @@ config ARM64
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_RCU_TABLE_FREE
+ select HAVE_PREEMPT_LAZY
select HAVE_SYSCALL_TRACEPOINTS
select IRQ_DOMAIN
+ select IRQ_FORCED_THREADING
select MODULES_USE_ELF_RELA
select NO_BOOTMEM
select OF
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 459bf8e53208..3e24ea15c05c 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -50,6 +50,7 @@ struct thread_info {
struct exec_domain *exec_domain; /* execution domain */
struct restart_block restart_block;
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int preempt_lazy_count; /* 0 => preemptable, <0 => bug */
int cpu; /* cpu */
};
@@ -108,6 +109,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */
+#define TIF_NEED_RESCHED_LAZY 4
#define TIF_NOHZ 7
#define TIF_SYSCALL_TRACE 8
#define TIF_SYSCALL_AUDIT 9
@@ -124,6 +126,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE)
+#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY)
#define _TIF_NOHZ (1 << TIF_NOHZ)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 9a9fce090d58..f77413646dba 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -36,6 +36,7 @@ int main(void)
BLANK();
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
+ DEFINE(TI_PREEMPT_LAZY, offsetof(struct thread_info, preempt_lazy_count));
DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit));
DEFINE(TI_TASK, offsetof(struct thread_info, task));
DEFINE(TI_EXEC_DOMAIN, offsetof(struct thread_info, exec_domain));
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 2b0f3d5e11c7..0c7c7245b97c 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -367,11 +367,16 @@ ENDPROC(el1_sync)
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr w24, [tsk, #TI_PREEMPT] // get preempt count
- cbnz w24, 1f // preempt count != 0
+ cbnz w24, 2f // preempt count != 0
ldr x0, [tsk, #TI_FLAGS] // get flags
- tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
- bl el1_preempt
+ tbnz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
+
+ ldr w24, [tsk, #TI_PREEMPT_LAZY] // get preempt lazy count
+ cbnz w24, 2f // preempt lazy count != 0
+ tbz x0, #TIF_NEED_RESCHED_LAZY, 2f // needs rescheduling?
1:
+ bl el1_preempt
+2:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on
@@ -385,6 +390,7 @@ ENDPROC(el1_irq)
1: bl preempt_schedule_irq // irq en/disable is done inside
ldr x0, [tsk, #TI_FLAGS] // get new tasks TI_FLAGS
tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling?
+ tbnz x0, #TIF_NEED_RESCHED_LAZY, 1b // needs rescheduling?
ret x24
#endif
@@ -621,6 +627,7 @@ ENDPROC(cpu_switch_to)
str x0, [sp, #S_X0] // returned x0
work_pending:
tbnz x1, #TIF_NEED_RESCHED, work_resched
+ tbnz x1, #TIF_NEED_RESCHED_LAZY, work_resched
/* TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_FOREIGN_FPSTATE case */
ldr x2, [sp, #S_PSTATE]
mov x0, sp // 'regs'
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index aa29ecb4f800..70dcde67a808 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -461,7 +461,7 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
}
err = request_irq(irq, armpmu->handle_irq,
- IRQF_NOBALANCING,
+ IRQF_NOBALANCING | IRQF_NO_THREAD,
"arm-pmu", armpmu);
if (err) {
pr_err("unable to request IRQ%d for ARM PMU counters\n",
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 602eb51d20bc..60fc1adab19f 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -157,6 +157,7 @@ config KVM_E500MC
config KVM_MPIC
bool "KVM in-kernel MPIC emulation"
depends on KVM && E500
+ depends on !PREEMPT_RT_FULL
select HAVE_KVM_IRQCHIP
select HAVE_KVM_IRQFD
select HAVE_KVM_IRQ_ROUTING
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index 6a51619d8690..430e7987d6ad 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -119,7 +119,7 @@ typedef __uint64_t __psunsigned_t;
/*
* Feature macros (disable/enable)
*/
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_RT_FULL)
#define HAVE_PERCPU_SB /* per cpu superblock counters are a 2.6 feature */
#else
#undef HAVE_PERCPU_SB /* per cpu superblock counters are a 2.6 feature */
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 9dda38a377bf..171dfacb61d4 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -85,12 +85,9 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
raise_irqwork = llist_add(&work->llnode,
&per_cpu(hirq_work_list, cpu));
else
- raise_irqwork = llist_add(&work->llnode,
- &per_cpu(lazy_list, cpu));
-#else
+#endif
raise_irqwork = llist_add(&work->llnode,
&per_cpu(raised_list, cpu));
-#endif
if (raise_irqwork)
arch_send_call_function_single_ipi(cpu);
@@ -114,21 +111,20 @@ bool irq_work_queue(struct irq_work *work)
if (work->flags & IRQ_WORK_HARD_IRQ) {
if (llist_add(&work->llnode, this_cpu_ptr(&hirq_work_list)))
arch_irq_work_raise();
- } else {
+ } else
+#endif
+ if (work->flags & IRQ_WORK_LAZY) {
if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
tick_nohz_tick_stopped())
+#ifdef CONFIG_PREEMPT_RT_FULL
raise_softirq(TIMER_SOFTIRQ);
- }
#else
- if (work->flags & IRQ_WORK_LAZY) {
- if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
- tick_nohz_tick_stopped())
arch_irq_work_raise();
+#endif
} else {
if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
arch_irq_work_raise();
}
-#endif
preempt_enable();
@@ -202,6 +198,13 @@ void irq_work_run(void)
{
#ifdef CONFIG_PREEMPT_RT_FULL
irq_work_run_list(this_cpu_ptr(&hirq_work_list));
+ /*
+ * NOTE: we raise softirq via IPI for safety (caller may hold locks
+ * that raise_softirq needs) and execute in irq_work_tick() to move
+ * the overhead from hard to soft irq context.
+ */
+ if (!llist_empty(this_cpu_ptr(&raised_list)))
+ raise_softirq(TIMER_SOFTIRQ);
#else
irq_work_run_list(this_cpu_ptr(&raised_list));
irq_work_run_list(this_cpu_ptr(&lazy_list));
@@ -211,15 +214,12 @@ EXPORT_SYMBOL_GPL(irq_work_run);
void irq_work_tick(void)
{
-#ifdef CONFIG_PREEMPT_RT_FULL
- irq_work_run_list(this_cpu_ptr(&lazy_list));
-#else
- struct llist_head *raised = &__get_cpu_var(raised_list);
+ struct llist_head *raised = this_cpu_ptr(&raised_list);
- if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
+ if (!llist_empty(raised) && (!arch_irq_work_has_interrupt() ||
+ IS_ENABLED(CONFIG_PREEMPT_RT_FULL)))
irq_work_run_list(raised);
- irq_work_run_list(&__get_cpu_var(lazy_list));
-#endif
+ irq_work_run_list(this_cpu_ptr(&lazy_list));
}
/*
diff --git a/localversion-rt b/localversion-rt
index 700c857efd9b..22746d6390a4 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt8
+-rt9
--
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