xref: /xnu-12377.41.6/osfmk/man/memory_object_perf_info.html (revision bbb1b6f9e71b8cdde6e5cd6f4841f207dee3d828)
1*bbb1b6f9SApple OSS Distributions<h2>memory_object_perf_info</h2>
2*bbb1b6f9SApple OSS Distributions<hr>
3*bbb1b6f9SApple OSS Distributions<p>
4*bbb1b6f9SApple OSS Distributions<strong>Structure</strong> - Specifies a memory object's attributes with respect to performance.
5*bbb1b6f9SApple OSS Distributions<h3>SYNOPSIS</h3>
6*bbb1b6f9SApple OSS Distributions<pre>
7*bbb1b6f9SApple OSS Distributions<strong>struct  memory_object_perf_info</strong>
8*bbb1b6f9SApple OSS Distributions<strong>{</strong>
9*bbb1b6f9SApple OSS Distributions        <strong>vm_offset_t</strong>      <var>cluster_size</var><strong>;</strong>
10*bbb1b6f9SApple OSS Distributions        <strong>boolean_t</strong>    <var>may_cache_object</var><strong>;</strong>
11*bbb1b6f9SApple OSS Distributions<strong>};</strong>
12*bbb1b6f9SApple OSS Distributions
13*bbb1b6f9SApple OSS Distributions<strong>typedef struct memory_object_perf_info* memory_object_perf_info_t;</strong>
14*bbb1b6f9SApple OSS Distributions</pre>
15*bbb1b6f9SApple OSS Distributions<h3>FIELDS</h3>
16*bbb1b6f9SApple OSS Distributions<dl>
17*bbb1b6f9SApple OSS Distributions<dt> <var>cluster_size</var>
18*bbb1b6f9SApple OSS Distributions<dd>
19*bbb1b6f9SApple OSS DistributionsPreferred cluster size (in bytes) for the memory object.  This helps to
20*bbb1b6f9SApple OSS Distributionsdetermine how many pages are transferred in individual data request
21*bbb1b6f9SApple OSS Distributionsand return messages.
22*bbb1b6f9SApple OSS Distributions<p>
23*bbb1b6f9SApple OSS Distributions<dt> <var>may_cache_object</var>
24*bbb1b6f9SApple OSS Distributions<dd>
25*bbb1b6f9SApple OSS DistributionsCache indicator.  If true, the kernel can cache data associated with the
26*bbb1b6f9SApple OSS Distributionsmemory object (keep the memory object active) even if no virtual
27*bbb1b6f9SApple OSS Distributionsmemory references to it remain.
28*bbb1b6f9SApple OSS Distributions</dl>
29*bbb1b6f9SApple OSS Distributions<h3>DESCRIPTION</h3>
30*bbb1b6f9SApple OSS Distributions<p>
31*bbb1b6f9SApple OSS DistributionsThe <strong>memory_object_perf_info</strong> structure
32*bbb1b6f9SApple OSS Distributionsdefines a memory object's character with respect to performance.
33*bbb1b6f9SApple OSS Distributions<h3>NOTES</h3>
34*bbb1b6f9SApple OSS Distributions<p>
35*bbb1b6f9SApple OSS DistributionsSharing cached data among all the clients of a memory object can have a major
36*bbb1b6f9SApple OSS Distributionsimpact on performance, especially if it can be extended across successive, as
37*bbb1b6f9SApple OSS Distributionswell as concurrent, uses.  For example, the memory objects that represent
38*bbb1b6f9SApple OSS Distributionsprogram images can be used regularly by different programs.
39*bbb1b6f9SApple OSS DistributionsBy retaining the data
40*bbb1b6f9SApple OSS Distributionsfor these memory objects in cache, the number of secondary storage accesses
41*bbb1b6f9SApple OSS Distributionscan be reduced significantly.
42*bbb1b6f9SApple OSS Distributions<h3>RELATED INFORMATION</h3>
43*bbb1b6f9SApple OSS Distributions<p>
44*bbb1b6f9SApple OSS DistributionsFunctions:
45*bbb1b6f9SApple OSS Distributions<a href="MO_get_attributes.html"><strong>memory_object_get_attributes</strong></a>,
46*bbb1b6f9SApple OSS Distributions<a href="MO_change_attributes.html"><strong>memory_object_change_attributes</strong></a>,
47*bbb1b6f9SApple OSS Distributions<a href="vm_region.html"><strong>vm_region</strong></a>,
48*bbb1b6f9SApple OSS Distributions<a href="memory_object_synchronize.html"><strong>memory_object_synchronize</strong></a>,
49*bbb1b6f9SApple OSS Distributions<a href="VSD_memory_manager.html"><strong>vm_set_default_memory_manager</strong></a>,
50*bbb1b6f9SApple OSS Distributions<a href="vm_msync.html"><strong>vm_msync</strong></a>.
51*bbb1b6f9SApple OSS Distributions<p>
52*bbb1b6f9SApple OSS DistributionsStructures:
53*bbb1b6f9SApple OSS Distributions<a href="memory_object_attr_info.html"><strong>memory_object_attr_info</strong></a>.
54