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34b133f8e9
The spinning mutex implementation uses cpu_relax() in busy loops as a compiler barrier. Depending on the architecture, cpu_relax() may do more than needed in this specific mutex spin loops. On System z we also give up the time slice of the virtual cpu in cpu_relax(), which prevents effective spinning on the mutex. This patch replaces cpu_relax() in the spinning mutex code with arch_mutex_cpu_relax(), which can be defined by each architecture that selects HAVE_ARCH_MUTEX_CPU_RELAX. The default is still cpu_relax(), so this patch should not affect other architectures than System z for now. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1290437256.7455.4.camel@thinkpad> Signed-off-by: Ingo Molnar <mingo@elte.hu>
182 lines
4.8 KiB
Plaintext
182 lines
4.8 KiB
Plaintext
#
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# General architecture dependent options
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#
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config OPROFILE
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tristate "OProfile system profiling"
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depends on PROFILING
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depends on HAVE_OPROFILE
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select RING_BUFFER
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select RING_BUFFER_ALLOW_SWAP
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help
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OProfile is a profiling system capable of profiling the
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whole system, include the kernel, kernel modules, libraries,
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and applications.
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If unsure, say N.
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config OPROFILE_EVENT_MULTIPLEX
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bool "OProfile multiplexing support (EXPERIMENTAL)"
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default n
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depends on OPROFILE && X86
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help
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The number of hardware counters is limited. The multiplexing
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feature enables OProfile to gather more events than counters
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are provided by the hardware. This is realized by switching
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between events at an user specified time interval.
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If unsure, say N.
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config HAVE_OPROFILE
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bool
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config KPROBES
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bool "Kprobes"
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depends on MODULES
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depends on HAVE_KPROBES
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select KALLSYMS
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help
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Kprobes allows you to trap at almost any kernel address and
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execute a callback function. register_kprobe() establishes
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a probepoint and specifies the callback. Kprobes is useful
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for kernel debugging, non-intrusive instrumentation and testing.
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If in doubt, say "N".
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config JUMP_LABEL
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bool "Optimize trace point call sites"
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depends on HAVE_ARCH_JUMP_LABEL
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help
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If it is detected that the compiler has support for "asm goto",
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the kernel will compile trace point locations with just a
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nop instruction. When trace points are enabled, the nop will
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be converted to a jump to the trace function. This technique
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lowers overhead and stress on the branch prediction of the
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processor.
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On i386, options added to the compiler flags may increase
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the size of the kernel slightly.
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config OPTPROBES
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def_bool y
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depends on KPROBES && HAVE_OPTPROBES
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depends on !PREEMPT
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config HAVE_EFFICIENT_UNALIGNED_ACCESS
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bool
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help
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Some architectures are unable to perform unaligned accesses
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without the use of get_unaligned/put_unaligned. Others are
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unable to perform such accesses efficiently (e.g. trap on
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unaligned access and require fixing it up in the exception
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handler.)
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This symbol should be selected by an architecture if it can
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perform unaligned accesses efficiently to allow different
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code paths to be selected for these cases. Some network
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drivers, for example, could opt to not fix up alignment
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problems with received packets if doing so would not help
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much.
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See Documentation/unaligned-memory-access.txt for more
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information on the topic of unaligned memory accesses.
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config HAVE_SYSCALL_WRAPPERS
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bool
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config KRETPROBES
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def_bool y
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depends on KPROBES && HAVE_KRETPROBES
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config USER_RETURN_NOTIFIER
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bool
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depends on HAVE_USER_RETURN_NOTIFIER
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help
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Provide a kernel-internal notification when a cpu is about to
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switch to user mode.
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config HAVE_IOREMAP_PROT
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bool
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config HAVE_KPROBES
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bool
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config HAVE_KRETPROBES
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bool
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config HAVE_OPTPROBES
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bool
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#
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# An arch should select this if it provides all these things:
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#
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# task_pt_regs() in asm/processor.h or asm/ptrace.h
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# arch_has_single_step() if there is hardware single-step support
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# arch_has_block_step() if there is hardware block-step support
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# asm/syscall.h supplying asm-generic/syscall.h interface
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# linux/regset.h user_regset interfaces
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# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
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# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
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# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
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# signal delivery calls tracehook_signal_handler()
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#
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config HAVE_ARCH_TRACEHOOK
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bool
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config HAVE_DMA_ATTRS
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bool
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config USE_GENERIC_SMP_HELPERS
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bool
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config HAVE_REGS_AND_STACK_ACCESS_API
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bool
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help
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This symbol should be selected by an architecure if it supports
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the API needed to access registers and stack entries from pt_regs,
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declared in asm/ptrace.h
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For example the kprobes-based event tracer needs this API.
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config HAVE_CLK
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bool
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help
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The <linux/clk.h> calls support software clock gating and
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thus are a key power management tool on many systems.
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config HAVE_DMA_API_DEBUG
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bool
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config HAVE_DEFAULT_NO_SPIN_MUTEXES
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bool
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config HAVE_HW_BREAKPOINT
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bool
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depends on PERF_EVENTS
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config HAVE_MIXED_BREAKPOINTS_REGS
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bool
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depends on HAVE_HW_BREAKPOINT
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help
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Depending on the arch implementation of hardware breakpoints,
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some of them have separate registers for data and instruction
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breakpoints addresses, others have mixed registers to store
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them but define the access type in a control register.
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Select this option if your arch implements breakpoints under the
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latter fashion.
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config HAVE_USER_RETURN_NOTIFIER
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bool
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config HAVE_PERF_EVENTS_NMI
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bool
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help
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System hardware can generate an NMI using the perf event
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subsystem. Also has support for calculating CPU cycle events
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to determine how many clock cycles in a given period.
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config HAVE_ARCH_JUMP_LABEL
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bool
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config HAVE_ARCH_MUTEX_CPU_RELAX
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bool
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source "kernel/gcov/Kconfig"
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