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Implement two-phase decay-based purging.

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Split decay-based purging into two phases, the first of which uses lazy
purging to convert dirty pages to "muzzy", and the second of which uses
forced purging, decommit, or unmapping to convert pages to clean or
destroy them altogether.  Not all operating systems support lazy
purging, yet the application may provide extent hooks that implement
lazy purging, so care must be taken to dynamically omit the first phase
when necessary.

The mallctl interfaces change as follows:
- opt.decay_time --> opt.{dirty,muzzy}_decay_time
- arena.<i>.decay_time --> arena.<i>.{dirty,muzzy}_decay_time
- arenas.decay_time --> arenas.{dirty,muzzy}_decay_time
- stats.arenas.<i>.pdirty --> stats.arenas.<i>.p{dirty,muzzy}
- stats.arenas.<i>.{npurge,nmadvise,purged} -->
  stats.arenas.<i>.{dirty,muzzy}_{npurge,nmadvise,purged}

This resolves #521.
This commit is contained in:
Jason Evans
2017-03-08 22:42:57 -08:00
parent 38a5bfc816
commit 64e458f5cd
23 changed files with 1078 additions and 490 deletions
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241
doc/jemalloc.xml.in
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@@ -944,24 +944,54 @@ mallctl("arena." STRINGIFY(MALLCTL_ARENAS_ALL) ".decay",
<quote>percpu</quote>. </para></listitem>
</varlistentry>
<varlistentry id="opt.decay_time">
<varlistentry id="opt.dirty_decay_time">
<term>
<mallctl>opt.decay_time</mallctl>
<mallctl>opt.dirty_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>r-</literal>
</term>
<listitem><para>Approximate time in seconds from the creation of a set
of unused dirty pages until an equivalent set of unused dirty pages is
purged and/or reused. The pages are incrementally purged according to a
sigmoidal decay curve that starts and ends with zero purge rate. A
decay time of 0 causes all unused dirty pages to be purged immediately
upon creation. A decay time of -1 disables purging. The default decay
time is 10 seconds. See <link
linkend="arenas.decay_time"><mallctl>arenas.decay_time</mallctl></link>
purged (i.e. converted to muzzy via e.g.
<function>madvise(<parameter>...</parameter><parameter><constant>MADV_FREE</constant></parameter>)</function>
if supported by the operating system, or converted to clean otherwise)
and/or reused. Dirty pages are defined as previously having been
potentially written to by the application, and therefore consuming
physical memory, yet having no current use. The pages are incrementally
purged according to a sigmoidal decay curve that starts and ends with
zero purge rate. A decay time of 0 causes all unused dirty pages to be
purged immediately upon creation. A decay time of -1 disables purging.
The default decay time is 10 seconds. See <link
linkend="arenas.dirty_decay_time"><mallctl>arenas.dirty_decay_time</mallctl></link>
and <link
linkend="arena.i.decay_time"><mallctl>arena.&lt;i&gt;.decay_time</mallctl></link>
for related dynamic control options.
</para></listitem>
linkend="arena.i.muzzy_decay_time"><mallctl>arena.&lt;i&gt;.muzzy_decay_time</mallctl></link>
for related dynamic control options. See <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzzy_decay_time</mallctl></link>
for a description of muzzy pages.</para></listitem>
</varlistentry>
<varlistentry id="opt.muzzy_decay_time">
<term>
<mallctl>opt.muzzy_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>r-</literal>
</term>
<listitem><para>Approximate time in seconds from the creation of a set
of unused muzzy pages until an equivalent set of unused muzzy pages is
purged (i.e. converted to clean) and/or reused. Muzzy pages are defined
as previously having been unused dirty pages that were subsequently
purged in a manner that left them subject to the reclamation whims of
the operating system (e.g.
<function>madvise(<parameter>...</parameter><parameter><constant>MADV_FREE</constant></parameter>)</function>),
and therefore in an indeterminate state. The pages are incrementally
purged according to a sigmoidal decay curve that starts and ends with
zero purge rate. A decay time of 0 causes all unused muzzy pages to be
purged immediately upon creation. A decay time of -1 disables purging.
The default decay time is 10 seconds. See <link
linkend="arenas.muzzy_decay_time"><mallctl>arenas.muzzy_decay_time</mallctl></link>
and <link
linkend="arena.i.muzzy_decay_time"><mallctl>arena.&lt;i&gt;.muzzy_decay_time</mallctl></link>
for related dynamic control options.</para></listitem>
</varlistentry>
<varlistentry id="opt.stats_print">
@@ -1460,6 +1490,22 @@ malloc_conf = "xmalloc:true";]]></programlisting>
initialized (always true).</para></listitem>
</varlistentry>
<varlistentry id="arena.i.decay">
<term>
<mallctl>arena.&lt;i&gt;.decay</mallctl>
(<type>void</type>)
<literal>--</literal>
</term>
<listitem><para>Trigger decay-based purging of unused dirty/muzzy pages
for arena &lt;i&gt;, or for all arenas if &lt;i&gt; equals
<constant>MALLCTL_ARENAS_ALL</constant>. The proportion of unused
dirty/muzzy pages to be purged depends on the current time; see <link
linkend="opt.dirty_decay_time"><mallctl>opt.dirty_decay_time</mallctl></link>
and <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzy_decay_time</mallctl></link>
for details.</para></listitem>
</varlistentry>
<varlistentry id="arena.i.purge">
<term>
<mallctl>arena.&lt;i&gt;.purge</mallctl>
@@ -1471,20 +1517,6 @@ malloc_conf = "xmalloc:true";]]></programlisting>
</para></listitem>
</varlistentry>
<varlistentry id="arena.i.decay">
<term>
<mallctl>arena.&lt;i&gt;.decay</mallctl>
(<type>void</type>)
<literal>--</literal>
</term>
<listitem><para>Trigger decay-based purging of unused dirty pages for
arena &lt;i&gt;, or for all arenas if &lt;i&gt; equals
<constant>MALLCTL_ARENAS_ALL</constant>. The proportion of unused dirty
pages to be purged depends on the current time; see <link
linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for
details.</para></listitem>
</varlistentry>
<varlistentry id="arena.i.reset">
<term>
<mallctl>arena.&lt;i&gt;.reset</mallctl>
@@ -1532,9 +1564,9 @@ malloc_conf = "xmalloc:true";]]></programlisting>
settings.</para></listitem>
</varlistentry>
<varlistentry id="arena.i.decay_time">
<varlistentry id="arena.i.dirty_decay_time">
<term>
<mallctl>arena.&lt;i&gt;.decay_time</mallctl>
<mallctl>arena.&lt;i&gt;.dirty_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>rw</literal>
</term>
@@ -1544,8 +1576,24 @@ malloc_conf = "xmalloc:true";]]></programlisting>
set, all currently unused dirty pages are considered to have fully
decayed, which causes immediate purging of all unused dirty pages unless
the decay time is set to -1 (i.e. purging disabled). See <link
linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for
additional information.</para></listitem>
linkend="opt.dirty_decay_time"><mallctl>opt.dirty_decay_time</mallctl></link>
for additional information.</para></listitem>
</varlistentry>
<varlistentry id="arena.i.muzzy_decay_time">
<term>
<mallctl>arena.&lt;i&gt;.muzzy_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>rw</literal>
</term>
<listitem><para>Current per-arena approximate time in seconds from the
creation of a set of unused muzzy pages until an equivalent set of
unused muzzy pages is purged and/or reused. Each time this interface is
set, all currently unused muzzy pages are considered to have fully
decayed, which causes immediate purging of all unused muzzy pages unless
the decay time is set to -1 (i.e. purging disabled). See <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzzy_decay_time</mallctl></link>
for additional information.</para></listitem>
</varlistentry>
<varlistentry id="arena.i.extent_hooks">
@@ -1584,7 +1632,7 @@ struct extent_hooks_s {
mapped committed memory, in the simplest case followed by deallocation.
However, there are performance and platform reasons to retain extents
for later reuse. Cleanup attempts cascade from deallocation to decommit
to lazy purging to forced purging, which gives the extent management
to forced purging to lazy purging, which gives the extent management
functions opportunities to reject the most permanent cleanup operations
in favor of less permanent (and often less costly) operations. All
operations except allocation can be universally opted out of by setting
@@ -1707,12 +1755,14 @@ struct extent_hooks_s {
<parameter>addr</parameter> and <parameter>size</parameter> at
<parameter>offset</parameter> bytes, extending for
<parameter>length</parameter> on behalf of arena
<parameter>arena_ind</parameter>. A lazy extent purge function can
delay purging indefinitely and leave the pages within the purged virtual
memory range in an indeterminite state, whereas a forced extent purge
function immediately purges, and the pages within the virtual memory
range will be zero-filled the next time they are accessed. If the
function returns true, this indicates failure to purge.</para>
<parameter>arena_ind</parameter>. A lazy extent purge function (e.g.
implemented via
<function>madvise(<parameter>...</parameter><parameter><constant>MADV_FREE</constant></parameter>)</function>)
can delay purging indefinitely and leave the pages within the purged
virtual memory range in an indeterminite state, whereas a forced extent
purge function immediately purges, and the pages within the virtual
memory range will be zero-filled the next time they are accessed. If
the function returns true, this indicates failure to purge.</para>
<funcsynopsis><funcprototype>
<funcdef>typedef bool <function>(extent_split_t)</function></funcdef>
@@ -1769,19 +1819,34 @@ struct extent_hooks_s {
<listitem><para>Current limit on number of arenas.</para></listitem>
</varlistentry>
<varlistentry id="arenas.decay_time">
<varlistentry id="arenas.dirty_decay_time">
<term>
<mallctl>arenas.decay_time</mallctl>
<mallctl>arenas.dirty_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>rw</literal>
</term>
<listitem><para>Current default per-arena approximate time in seconds
from the creation of a set of unused dirty pages until an equivalent set
of unused dirty pages is purged and/or reused, used to initialize <link
linkend="arena.i.decay_time"><mallctl>arena.&lt;i&gt;.decay_time</mallctl></link>
linkend="arena.i.dirty_decay_time"><mallctl>arena.&lt;i&gt;.dirty_decay_time</mallctl></link>
during arena creation. See <link
linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for
additional information.</para></listitem>
linkend="opt.dirty_decay_time"><mallctl>opt.dirty_decay_time</mallctl></link>
for additional information.</para></listitem>
</varlistentry>
<varlistentry id="arenas.muzzy_decay_time">
<term>
<mallctl>arenas.muzzy_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>rw</literal>
</term>
<listitem><para>Current default per-arena approximate time in seconds
from the creation of a set of unused muzzy pages until an equivalent set
of unused muzzy pages is purged and/or reused, used to initialize <link
linkend="arena.i.muzzy_decay_time"><mallctl>arena.&lt;i&gt;.muzzy_decay_time</mallctl></link>
during arena creation. See <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzzy_decay_time</mallctl></link>
for additional information.</para></listitem>
</varlistentry>
<varlistentry id="arenas.quantum">
@@ -2014,7 +2079,9 @@ struct extent_hooks_s {
equal to <link
linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link>.
This does not include <link linkend="stats.arenas.i.pdirty">
<mallctl>stats.arenas.&lt;i&gt;.pdirty</mallctl></link>, nor pages
<mallctl>stats.arenas.&lt;i&gt;.pdirty</mallctl></link>,
<link linkend="stats.arenas.i.pmuzzy">
<mallctl>stats.arenas.&lt;i&gt;.pmuzzy</mallctl></link>, nor pages
entirely devoted to allocator metadata.</para></listitem>
</varlistentry>
@@ -2099,16 +2166,29 @@ struct extent_hooks_s {
</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.decay_time">
<varlistentry id="stats.arenas.i.dirty_decay_time">
<term>
<mallctl>stats.arenas.&lt;i&gt;.decay_time</mallctl>
<mallctl>stats.arenas.&lt;i&gt;.dirty_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>r-</literal>
</term>
<listitem><para>Approximate time in seconds from the creation of a set
of unused dirty pages until an equivalent set of unused dirty pages is
purged and/or reused. See <link
linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link>
linkend="opt.dirty_decay_time"><mallctl>opt.dirty_decay_time</mallctl></link>
for details.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.muzzy_decay_time">
<term>
<mallctl>stats.arenas.&lt;i&gt;.muzzy_decay_time</mallctl>
(<type>ssize_t</type>)
<literal>r-</literal>
</term>
<listitem><para>Approximate time in seconds from the creation of a set
of unused muzzy pages until an equivalent set of unused muzzy pages is
purged and/or reused. See <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzzy_decay_time</mallctl></link>
for details.</para></listitem>
</varlistentry>
@@ -2138,10 +2218,22 @@ struct extent_hooks_s {
<literal>r-</literal>
</term>
<listitem><para>Number of pages within unused extents that are
potentially dirty, and for which
<function>madvise(<parameter>...</parameter>
<parameter><constant>MADV_DONTNEED</constant></parameter>)</function> or
similar has not been called.</para></listitem>
potentially dirty, and for which <function>madvise()</function> or
similar has not been called. See <link
linkend="opt.dirty_decay_time"><mallctl>opt.dirty_decay_time</mallctl></link>
for a description of dirty pages.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.pmuzzy">
<term>
<mallctl>stats.arenas.&lt;i&gt;.pmuzzy</mallctl>
(<type>size_t</type>)
<literal>r-</literal>
</term>
<listitem><para>Number of pages within unused extents that are muzzy.
See <link
linkend="opt.muzzy_decay_time"><mallctl>opt.muzzy_decay_time</mallctl></link>
for a description of muzzy pages.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.mapped">
@@ -2207,9 +2299,9 @@ struct extent_hooks_s {
size.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.npurge">
<varlistentry id="stats.arenas.i.dirty_npurge">
<term>
<mallctl>stats.arenas.&lt;i&gt;.npurge</mallctl>
<mallctl>stats.arenas.&lt;i&gt;.dirty_npurge</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
@@ -2218,26 +2310,57 @@ struct extent_hooks_s {
</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.nmadvise">
<varlistentry id="stats.arenas.i.dirty_nmadvise">
<term>
<mallctl>stats.arenas.&lt;i&gt;.nmadvise</mallctl>
<mallctl>stats.arenas.&lt;i&gt;.dirty_nmadvise</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
</term>
<listitem><para>Number of <function>madvise(<parameter>...</parameter>
<parameter><constant>MADV_DONTNEED</constant></parameter>)</function> or
similar calls made to purge dirty pages.</para></listitem>
<listitem><para>Number of <function>madvise()</function> or similar
calls made to purge dirty pages.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.purged">
<varlistentry id="stats.arenas.i.dirty_purged">
<term>
<mallctl>stats.arenas.&lt;i&gt;.purged</mallctl>
<mallctl>stats.arenas.&lt;i&gt;.dirty_purged</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
</term>
<listitem><para>Number of pages purged.</para></listitem>
<listitem><para>Number of dirty pages purged.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.muzzy_npurge">
<term>
<mallctl>stats.arenas.&lt;i&gt;.muzzy_npurge</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
</term>
<listitem><para>Number of muzzy page purge sweeps performed.
</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.muzzy_nmadvise">
<term>
<mallctl>stats.arenas.&lt;i&gt;.muzzy_nmadvise</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
</term>
<listitem><para>Number of <function>madvise()</function> or similar
calls made to purge muzzy pages.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.muzzy_purged">
<term>
<mallctl>stats.arenas.&lt;i&gt;.muzzy_purged</mallctl>
(<type>uint64_t</type>)
<literal>r-</literal>
[<option>--enable-stats</option>]
</term>
<listitem><para>Number of muzzy pages purged.</para></listitem>
</varlistentry>
<varlistentry id="stats.arenas.i.small.allocated">