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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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baa36046d0
The archs that implement virtual cputime accounting all flush the cputime of a task when it gets descheduled and sometimes set up some ground initialization for the next task to account its cputime. These archs all put their own hooks in their context switch callbacks and handle the off-case themselves. Consolidate this by creating a new account_switch_vtime() callback called in generic code right after a context switch and that these archs must implement to flush the prev task cputime and initialize the next task cputime related state. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/*
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* Low-level task switching. This is based on information published in
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* the Processor Abstraction Layer and the System Abstraction Layer
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* manual.
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*
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* Copyright (C) 1998-2003 Hewlett-Packard Co
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* David Mosberger-Tang <davidm@hpl.hp.com>
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* Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
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* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
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*/
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#ifndef _ASM_IA64_SWITCH_TO_H
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#define _ASM_IA64_SWITCH_TO_H
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#include <linux/percpu.h>
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struct task_struct;
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/*
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* Context switch from one thread to another. If the two threads have
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* different address spaces, schedule() has already taken care of
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* switching to the new address space by calling switch_mm().
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*
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* Disabling access to the fph partition and the debug-register
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* context switch MUST be done before calling ia64_switch_to() since a
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* newly created thread returns directly to
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* ia64_ret_from_syscall_clear_r8.
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*/
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extern struct task_struct *ia64_switch_to (void *next_task);
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extern void ia64_save_extra (struct task_struct *task);
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extern void ia64_load_extra (struct task_struct *task);
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#ifdef CONFIG_PERFMON
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DECLARE_PER_CPU(unsigned long, pfm_syst_info);
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# define PERFMON_IS_SYSWIDE() (__get_cpu_var(pfm_syst_info) & 0x1)
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#else
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# define PERFMON_IS_SYSWIDE() (0)
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#endif
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#define IA64_HAS_EXTRA_STATE(t) \
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((t)->thread.flags & (IA64_THREAD_DBG_VALID|IA64_THREAD_PM_VALID) \
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|| PERFMON_IS_SYSWIDE())
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#define __switch_to(prev,next,last) do { \
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if (IA64_HAS_EXTRA_STATE(prev)) \
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ia64_save_extra(prev); \
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if (IA64_HAS_EXTRA_STATE(next)) \
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ia64_load_extra(next); \
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ia64_psr(task_pt_regs(next))->dfh = !ia64_is_local_fpu_owner(next); \
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(last) = ia64_switch_to((next)); \
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} while (0)
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#ifdef CONFIG_SMP
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/*
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* In the SMP case, we save the fph state when context-switching away from a thread that
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* modified fph. This way, when the thread gets scheduled on another CPU, the CPU can
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* pick up the state from task->thread.fph, avoiding the complication of having to fetch
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* the latest fph state from another CPU. In other words: eager save, lazy restore.
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*/
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# define switch_to(prev,next,last) do { \
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if (ia64_psr(task_pt_regs(prev))->mfh && ia64_is_local_fpu_owner(prev)) { \
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ia64_psr(task_pt_regs(prev))->mfh = 0; \
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(prev)->thread.flags |= IA64_THREAD_FPH_VALID; \
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__ia64_save_fpu((prev)->thread.fph); \
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} \
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__switch_to(prev, next, last); \
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/* "next" in old context is "current" in new context */ \
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if (unlikely((current->thread.flags & IA64_THREAD_MIGRATION) && \
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(task_cpu(current) != \
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task_thread_info(current)->last_cpu))) { \
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platform_migrate(current); \
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task_thread_info(current)->last_cpu = task_cpu(current); \
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} \
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} while (0)
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#else
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# define switch_to(prev,next,last) __switch_to(prev, next, last)
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#endif
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#endif /* _ASM_IA64_SWITCH_TO_H */
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