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perf (sometimes called "Perf Events"〔Vince Weaver, (The Unofficial Linux Perf Events Web-Page )〕 or perf tools, originally "Performance Counters for Linux", PCL〔(Linux perf event Features and Overhead ) // 2013 FastPath Workshop, Vince Weaver〕) is a performance analyzing tool in Linux, available from Linux kernel version 2.6.31.〔Jake Edge, (Perfcounters added to the mainline ), LWN July 1, 2009, "perfcounters being included into the mainline during the recently completed 2.6.31 merge window"〕 Userspace controlling utility, named perf, is accessed from the command line and provides a number of subcommands; it is capable of statistical profiling of the entire system (both kernel and userland code). It supports hardware performance counters, tracepoints, software performance counters (e.g. hrtimer), and dynamic probes (for example, kprobes or uprobes).〔 In 2012, IBM recognized perf (along with OProfile) as one of the two most commonly used performance counter profiling tools on Linux.〔A. Zanella, R. Arnold. (Evaluate performance for Linux on POWER. Analyze performance using Linux tools ), 12 Jun 2012 // IBM DeveloperWorks Technical library〕 == Implementation == The interface between a utility and the kernel consists of only one syscall and is done via a file descriptor and a mmaped memory region.〔Roberto A. Vitillo (LBNL). (PERFORMANCE TOOLS DEVELOPMENTS ), 16 June 2011, presentation from "Future computing in particle physics" conference〕 Unlike oprofile or LTTng, no service daemons are needed, as most functionality is integrated into the kernel. The perf utility dumps raw data from the mmaped buffer to disk when the buffer becomes filled up. According to R. Vitillo (LBNL), profiling performed by perf involves a very low overhead.〔 , architectures that provide support for hardware counters include x86, PowerPC64, UltraSPARC (III and IV), ARM (v5, v6, v7, Cortex-A8 and -A9), Alpha EV56 and SuperH.〔Arnaldo Carvalho de Melo, (The New Linux ’perf’ tools ), presentation from Linux Kongress, September, 2010〕 Usage of Last Branch Records, a branch tracing implementation available in Intel CPUs since Pentium 4, is available as a patch.〔 Since version 3.14 of the Linux kernel mainline, released on March 31, 2014, perf also supports ''running average power limit'' (RAPL) for power consumption measurements, which is available as a feature of certain Intel CPUs. Perf is natively supported in many popular Linux distributions, including Red Hat Enterprise Linux (since its version 6 released in 2010)〔(6.4. Performance Counters for Linux (PCL) Tools and perf ) // RHEL Developer Guide〕 and Debian (since its ''Squeeze'' version released in 2011). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Perf (Linux)」の詳細全文を読む スポンサード リンク
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