s390/vtime: Use the generic IRQ entry accounting

s390 has its own version of IRQ entry accounting because it doesn't
account the idle time the same way the other architectures do. Only
the actual idle sleep time is accounted as idle time, the rest of the
idle task execution is accounted as system time.

Make the generic IRQ entry accounting aware of architectures that have
their own way of accounting idle time and convert s390 to use it.

This prepares s390 to get involved in further consolidations of IRQ
time accounting.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201202115732.27827-3-frederic@kernel.org

diff --git a/arch/Kconfig b/arch/Kconfig
index 56b6ccc..0f151b4 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -627,6 +627,12 @@ config HAVE_TIF_NOHZ
 config HAVE_VIRT_CPU_ACCOUNTING
        bool
 
+config HAVE_VIRT_CPU_ACCOUNTING_IDLE
+       bool
+       help
+         Architecture has its own way to account idle CPU time and therefore
+         doesn't implement vtime_account_idle().
+
 config ARCH_HAS_SCALED_CPUTIME
        bool
 
@@ -641,7 +647,6 @@ config HAVE_VIRT_CPU_ACCOUNTING_GEN
          some 32-bit arches may require multiple accesses, so proper
          locking is needed to protect against concurrent accesses.
 
-
 config HAVE_IRQ_TIME_ACCOUNTING
        bool
        help

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 4a2a12b..6f1fdcd 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -181,6 +181,7 @@ config S390
        select HAVE_RSEQ
        select HAVE_SYSCALL_TRACEPOINTS
        select HAVE_VIRT_CPU_ACCOUNTING
+       select HAVE_VIRT_CPU_ACCOUNTING_IDLE
        select IOMMU_HELPER             if PCI
        select IOMMU_SUPPORT            if PCI
        select MODULES_USE_ELF_RELA

diff --git a/arch/s390/include/asm/vtime.h b/arch/s390/include/asm/vtime.h
index 3622d4e..fac6a67 100644 (file)
--- a/arch/s390/include/asm/vtime.h
+++ b/arch/s390/include/asm/vtime.h
@@ -2,7 +2,6 @@
 #ifndef _S390_VTIME_H
 #define _S390_VTIME_H
 
-#define __ARCH_HAS_VTIME_ACCOUNT
 #define __ARCH_HAS_VTIME_TASK_SWITCH
 
 #endif /* _S390_VTIME_H */

diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index f9f2a11..ebd8e56 100644 (file)
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -247,10 +247,6 @@ void vtime_account_kernel(struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(vtime_account_kernel);
 
-void vtime_account_irq_enter(struct task_struct *tsk)
-__attribute__((alias("vtime_account_kernel")));
-
-
 /*
  * Sorted add to a list. List is linear searched until first bigger
  * element is found.

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 61ce9f9..2783162 100644 (file)
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -417,23 +417,14 @@ void vtime_task_switch(struct task_struct *prev)
 }
 # endif
 
-/*
- * Archs that account the whole time spent in the idle task
- * (outside irq) as idle time can rely on this and just implement
- * vtime_account_kernel() and vtime_account_idle(). Archs that
- * have other meaning of the idle time (s390 only includes the
- * time spent by the CPU when it's in low power mode) must override
- * vtime_account().
- */
-#ifndef __ARCH_HAS_VTIME_ACCOUNT
 void vtime_account_irq_enter(struct task_struct *tsk)
 {
-       if (!in_interrupt() && is_idle_task(tsk))
+       if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
+           !in_interrupt() && is_idle_task(tsk))
                vtime_account_idle(tsk);
        else
                vtime_account_kernel(tsk);
 }
-#endif /* __ARCH_HAS_VTIME_ACCOUNT */
 
 void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
                    u64 *ut, u64 *st)