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<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>1998</year><year>2018</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>instrument</title>
<prepared>Arndt Jonasson</prepared>
<responsible>Torbjörn Johnsson</responsible>
<docno>1</docno>
<approved>Björn Gustavsson</approved>
<checked></checked>
<date>98-04-01</date>
<rev>PA1</rev>
<file>instrument.sgml</file>
</header>
<module>instrument</module>
<modulesummary>Analysis and Utility Functions for Instrumentation</modulesummary>
<description>
<p>The module <c>instrument</c> contains support for studying the resource
usage in an Erlang runtime system. Currently, only the allocation of memory can
be studied.</p>
<note>
<p>Note that this whole module is experimental, and the representations
used as well as the functionality is likely to change in the future.</p>
</note>
</description>
<datatypes>
<datatype>
<name name="block_histogram"/>
<desc>
<p>A histogram of block sizes where each interval's upper bound is
twice as high as the one before it.</p>
<p>The upper bound of the first interval is provided by the function
that returned the histogram, and the last interval has no upper
bound.</p>
</desc>
</datatype>
<datatype>
<name name="allocation_summary"/>
<desc>
<p>A summary of allocated block sizes (including their headers) grouped
by their <c><anno>Origin</anno></c> and <c><anno>Type</anno></c>.</p>
<p><c><anno>Origin</anno></c> is generally which NIF or driver that
allocated the blocks, or 'system' if it could not be determined.</p>
<p><c><anno>Type</anno></c> is the allocation category that the blocks
belong to, e.g. <c>db_term</c>, <c>message</c> or <c>binary</c>.</p>
<p>If one or more carriers could not be scanned in full without harming
the responsiveness of the system, <c><anno>UnscannedSize</anno></c>
is the number of bytes that had to be skipped.</p>
</desc>
</datatype>
<datatype>
<name name="carrier_info_list"/>
<desc>
<p><c><anno>AllocatorType</anno></c> is the type of the allocator that
employs this carrier.</p>
<p><c><anno>TotalSize</anno></c> is the total size of the carrier,
including its header.</p>
<p><c><anno>AllocatedSize</anno></c> is the combined size of the
carrier's allocated blocks, including their headers.</p>
<p><c><anno>AllocatedCount</anno></c> is the number of allocated
blocks in the carrier.</p>
<p><c><anno>InPool</anno></c> is whether the carrier is in the
migration pool.</p>
<p><c><anno>FreeBlocks</anno></c> is a histogram of the free block
sizes in the carrier.</p>
<p>If the carrier could not be scanned in full without harming the
responsiveness of the system, <c><anno>UnscannedSize</anno></c> is
the number of bytes that had to be skipped.</p>
</desc>
</datatype>
</datatypes>
<funcs>
<func>
<name name="allocations" arity="0"/>
<fsummary>Return a summary of all allocations in the system.</fsummary>
<desc>
<p>Shorthand for
<seealso marker="#allocations/1"><c>allocations(#{})</c>.</seealso></p>
</desc>
</func>
<func>
<name name="allocations" arity="1"/>
<fsummary>Return a summary of all allocations filtered by allocator type
and scheduler id.</fsummary>
<desc>
<p>Returns a summary of all tagged allocations in the system,
optionally filtered by allocator type and scheduler id.</p>
<p>Only binaries and allocations made by NIFs and drivers are tagged by
default, but this can be configured an a per-allocator basis with the
<seealso marker="erts:erts_alloc#M_atags"><c>+M<S>atags</c>
</seealso> emulator option.</p>
<p>If tagged allocations are not enabled on any of the specified
allocator types, the call will fail with
<c>{error, not_enabled}</c>.</p>
<p>The following options can be used:</p>
<taglist>
<tag><c>allocator_types</c></tag>
<item>
<p>The allocator types that will be searched. Defaults to all
<c>alloc_util</c> allocators.</p>
</item>
<tag><c>scheduler_ids</c></tag>
<item>
<p>The scheduler ids whose allocator instances will be searched. A
scheduler id of 0 will refer to the global instance that is not
tied to any particular scheduler. Defaults to all schedulers and
the global instance.</p>
</item>
<tag><c>histogram_start</c></tag>
<item>
<p>The upper bound of the first interval in the allocated block
size histograms. Defaults to 128.</p>
</item>
<tag><c>histogram_width</c></tag>
<item>
<p>The number of intervals in the allocated block size histograms.
Defaults to 18.</p>
</item>
</taglist>
<p><em>Example:</em></p>
<code type="none"><![CDATA[
> instrument:allocations(#{ histogram_start => 128, histogram_width => 15 }).
{ok,{128,0,
#{udp_inet =>
#{driver_event_state => {0,0,0,0,0,0,0,0,0,1,0,0,0,0,0}},
system =>
#{heap => {0,0,0,0,20,4,2,2,2,3,0,1,0,0,1},
db_term => {271,3,1,52,80,1,0,0,0,0,0,0,0,0,0},
code => {0,0,0,5,3,6,11,22,19,20,10,2,1,0,0},
binary => {18,0,0,0,7,0,0,1,0,0,0,0,0,0,0},
message => {0,40,78,2,2,0,0,0,0,0,0,0,0,0,0},
... }
spawn_forker =>
#{driver_select_data_state =>
{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0}},
ram_file_drv => #{drv_binary => {0,0,0,0,0,0,1,0,0,0,0,0,0,0,0}},
prim_file =>
#{process_specific_data => {2,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
nif_trap_export_entry => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0},
monitor_extended => {0,1,0,0,0,0,0,0,0,0,0,0,0,0,0},
drv_binary => {0,0,0,0,0,0,1,0,3,5,0,0,0,1,0},
binary => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0}},
prim_buffer =>
#{nif_internal => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0},
binary => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0}}}}}
]]></code>
</desc>
</func>
<func>
<name name="carriers" arity="0"/>
<fsummary>Return a list of all carriers in the system.</fsummary>
<desc>
<p>Shorthand for
<seealso marker="#carriers/1"><c>carriers(#{})</c>.</seealso></p>
</desc>
</func>
<func>
<name name="carriers" arity="1"/>
<fsummary>Return a list of all carriers filtered by allocator type and
scheduler id.</fsummary>
<desc>
<p>Returns a summary of all carriers in the system, optionally filtered
by allocator type and scheduler id.</p>
<p>If the specified allocator types are not enabled, the call will fail
with <c>{error, not_enabled}</c>.</p>
<p>The following options can be used:</p>
<taglist>
<tag><c>allocator_types</c></tag>
<item>
<p>The allocator types that will be searched. Defaults to all
<c>alloc_util</c> allocators.</p>
</item>
<tag><c>scheduler_ids</c></tag>
<item>
<p>The scheduler ids whose allocator instances will be searched. A
scheduler id of 0 will refer to the global instance that is not
tied to any particular scheduler. Defaults to all schedulers and
the global instance.</p>
</item>
<tag><c>histogram_start</c></tag>
<item>
<p>The upper bound of the first interval in the free block size
histograms. Defaults to 512.</p>
</item>
<tag><c>histogram_width</c></tag>
<item>
<p>The number of intervals in the free block size histograms.
Defaults to 14.</p>
</item>
</taglist>
<p><em>Example:</em></p>
<code type="none"><![CDATA[
> instrument:carriers(#{ histogram_start => 512, histogram_width => 8 }).
{ok,{512,
[{ll_alloc,1048576,0,1048344,71,false,{0,0,0,0,0,0,0,0}},
{binary_alloc,1048576,0,324640,13,false,{3,0,0,1,0,0,0,2}},
{eheap_alloc,2097152,0,1037200,45,false,{2,1,1,3,4,3,2,2}},
{fix_alloc,32768,0,29544,82,false,{22,0,0,0,0,0,0,0}},
{...}|...]}}
]]></code>
</desc>
</func>
</funcs>
<section>
<title>See Also</title>
<p><seealso marker="erts:erts_alloc">erts_alloc(3)</seealso>,
<seealso marker="erts:erl">erl(1)</seealso></p>
</section>
</erlref>
