253 lines
8.7 KiB
Plaintext
253 lines
8.7 KiB
Plaintext
perf-list(1)
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============
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NAME
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----
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perf-list - List all symbolic event types
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SYNOPSIS
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--------
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[verse]
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'perf list' [hw|sw|cache|tracepoint|pmu|event_glob]
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DESCRIPTION
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-----------
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This command displays the symbolic event types which can be selected in the
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various perf commands with the -e option.
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[[EVENT_MODIFIERS]]
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EVENT MODIFIERS
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---------------
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Events can optionally have a modifier by appending a colon and one or
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more modifiers. Modifiers allow the user to restrict the events to be
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counted. The following modifiers exist:
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u - user-space counting
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k - kernel counting
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h - hypervisor counting
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I - non idle counting
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G - guest counting (in KVM guests)
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H - host counting (not in KVM guests)
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p - precise level
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P - use maximum detected precise level
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S - read sample value (PERF_SAMPLE_READ)
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D - pin the event to the PMU
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The 'p' modifier can be used for specifying how precise the instruction
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address should be. The 'p' modifier can be specified multiple times:
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0 - SAMPLE_IP can have arbitrary skid
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1 - SAMPLE_IP must have constant skid
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2 - SAMPLE_IP requested to have 0 skid
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3 - SAMPLE_IP must have 0 skid, or uses randomization to avoid
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sample shadowing effects.
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For Intel systems precise event sampling is implemented with PEBS
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which supports up to precise-level 2, and precise level 3 for
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some special cases
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On AMD systems it is implemented using IBS (up to precise-level 2).
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The precise modifier works with event types 0x76 (cpu-cycles, CPU
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clocks not halted) and 0xC1 (micro-ops retired). Both events map to
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IBS execution sampling (IBS op) with the IBS Op Counter Control bit
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(IbsOpCntCtl) set respectively (see AMD64 Architecture Programmer’s
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Manual Volume 2: System Programming, 13.3 Instruction-Based
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Sampling). Examples to use IBS:
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perf record -a -e cpu-cycles:p ... # use ibs op counting cycles
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perf record -a -e r076:p ... # same as -e cpu-cycles:p
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perf record -a -e r0C1:p ... # use ibs op counting micro-ops
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RAW HARDWARE EVENT DESCRIPTOR
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-----------------------------
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Even when an event is not available in a symbolic form within perf right now,
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it can be encoded in a per processor specific way.
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For instance For x86 CPUs NNN represents the raw register encoding with the
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layout of IA32_PERFEVTSELx MSRs (see [Intel® 64 and IA-32 Architectures Software Developer's Manual Volume 3B: System Programming Guide] Figure 30-1 Layout
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of IA32_PERFEVTSELx MSRs) or AMD's PerfEvtSeln (see [AMD64 Architecture Programmer’s Manual Volume 2: System Programming], Page 344,
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Figure 13-7 Performance Event-Select Register (PerfEvtSeln)).
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Note: Only the following bit fields can be set in x86 counter
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registers: event, umask, edge, inv, cmask. Esp. guest/host only and
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OS/user mode flags must be setup using <<EVENT_MODIFIERS, EVENT
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MODIFIERS>>.
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Example:
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If the Intel docs for a QM720 Core i7 describe an event as:
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Event Umask Event Mask
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Num. Value Mnemonic Description Comment
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A8H 01H LSD.UOPS Counts the number of micro-ops Use cmask=1 and
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delivered by loop stream detector invert to count
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cycles
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raw encoding of 0x1A8 can be used:
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perf stat -e r1a8 -a sleep 1
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perf record -e r1a8 ...
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You should refer to the processor specific documentation for getting these
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details. Some of them are referenced in the SEE ALSO section below.
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ARBITRARY PMUS
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--------------
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perf also supports an extended syntax for specifying raw parameters
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to PMUs. Using this typically requires looking up the specific event
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in the CPU vendor specific documentation.
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The available PMUs and their raw parameters can be listed with
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ls /sys/devices/*/format
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For example the raw event "LSD.UOPS" core pmu event above could
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be specified as
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perf stat -e cpu/event=0xa8,umask=0x1,name=LSD.UOPS_CYCLES,cmask=1/ ...
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PER SOCKET PMUS
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---------------
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Some PMUs are not associated with a core, but with a whole CPU socket.
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Events on these PMUs generally cannot be sampled, but only counted globally
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with perf stat -a. They can be bound to one logical CPU, but will measure
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all the CPUs in the same socket.
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This example measures memory bandwidth every second
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on the first memory controller on socket 0 of a Intel Xeon system
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perf stat -C 0 -a uncore_imc_0/cas_count_read/,uncore_imc_0/cas_count_write/ -I 1000 ...
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Each memory controller has its own PMU. Measuring the complete system
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bandwidth would require specifying all imc PMUs (see perf list output),
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and adding the values together.
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This example measures the combined core power every second
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perf stat -I 1000 -e power/energy-cores/ -a
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ACCESS RESTRICTIONS
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-------------------
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For non root users generally only context switched PMU events are available.
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This is normally only the events in the cpu PMU, the predefined events
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like cycles and instructions and some software events.
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Other PMUs and global measurements are normally root only.
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Some event qualifiers, such as "any", are also root only.
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This can be overriden by setting the kernel.perf_event_paranoid
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sysctl to -1, which allows non root to use these events.
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For accessing trace point events perf needs to have read access to
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/sys/kernel/debug/tracing, even when perf_event_paranoid is in a relaxed
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setting.
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TRACING
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-------
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Some PMUs control advanced hardware tracing capabilities, such as Intel PT,
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that allows low overhead execution tracing. These are described in a separate
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intel-pt.txt document.
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PARAMETERIZED EVENTS
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--------------------
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Some pmu events listed by 'perf-list' will be displayed with '?' in them. For
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example:
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hv_gpci/dtbp_ptitc,phys_processor_idx=?/
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This means that when provided as an event, a value for '?' must
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also be supplied. For example:
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perf stat -C 0 -e 'hv_gpci/dtbp_ptitc,phys_processor_idx=0x2/' ...
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EVENT GROUPS
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------------
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Perf supports time based multiplexing of events, when the number of events
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active exceeds the number of hardware performance counters. Multiplexing
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can cause measurement errors when the workload changes its execution
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profile.
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When metrics are computed using formulas from event counts, it is useful to
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ensure some events are always measured together as a group to minimize multiplexing
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errors. Event groups can be specified using { }.
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perf stat -e '{instructions,cycles}' ...
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The number of available performance counters depend on the CPU. A group
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cannot contain more events than available counters.
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For example Intel Core CPUs typically have four generic performance counters
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for the core, plus three fixed counters for instructions, cycles and
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ref-cycles. Some special events have restrictions on which counter they
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can schedule, and may not support multiple instances in a single group.
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When too many events are specified in the group none of them will not
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be measured.
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Globally pinned events can limit the number of counters available for
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other groups. On x86 systems, the NMI watchdog pins a counter by default.
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The nmi watchdog can be disabled as root with
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echo 0 > /proc/sys/kernel/nmi_watchdog
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Events from multiple different PMUs cannot be mixed in a group, with
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some exceptions for software events.
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LEADER SAMPLING
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---------------
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perf also supports group leader sampling using the :S specifier.
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perf record -e '{cycles,instructions}:S' ...
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perf report --group
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Normally all events in a event group sample, but with :S only
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the first event (the leader) samples, and it only reads the values of the
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other events in the group.
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OPTIONS
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-------
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Without options all known events will be listed.
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To limit the list use:
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. 'hw' or 'hardware' to list hardware events such as cache-misses, etc.
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. 'sw' or 'software' to list software events such as context switches, etc.
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. 'cache' or 'hwcache' to list hardware cache events such as L1-dcache-loads, etc.
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. 'tracepoint' to list all tracepoint events, alternatively use
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'subsys_glob:event_glob' to filter by tracepoint subsystems such as sched,
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block, etc.
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. 'pmu' to print the kernel supplied PMU events.
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. If none of the above is matched, it will apply the supplied glob to all
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events, printing the ones that match.
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. As a last resort, it will do a substring search in all event names.
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One or more types can be used at the same time, listing the events for the
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types specified.
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Support raw format:
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. '--raw-dump', shows the raw-dump of all the events.
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. '--raw-dump [hw|sw|cache|tracepoint|pmu|event_glob]', shows the raw-dump of
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a certain kind of events.
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SEE ALSO
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--------
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linkperf:perf-stat[1], linkperf:perf-top[1],
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linkperf:perf-record[1],
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http://www.intel.com/sdm/[Intel® 64 and IA-32 Architectures Software Developer's Manual Volume 3B: System Programming Guide],
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http://support.amd.com/us/Processor_TechDocs/24593_APM_v2.pdf[AMD64 Architecture Programmer’s Manual Volume 2: System Programming]
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