[apple/xnu.git] / osfmk / man / memory_object_perf_info.html

<h2>memory_object_perf_info</h2>\r<hr>\r<p>\r<strong>Structure</strong> - Specifies a memory object's attributes with respect to performance.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>struct  memory_object_perf_info</strong>\r<strong>{</strong>\r        <strong>vm_offset_t</strong>      <var>cluster_size</var><strong>;</strong>\r        <strong>boolean_t</strong>    <var>may_cache_object</var><strong>;</strong>\r<strong>};</strong>\r\r<strong>typedef struct memory_object_perf_info* memory_object_perf_info_t;</strong>\r</pre>\r<h3>FIELDS</h3>\r<dl>\r<dt> <var>cluster_size</var>\r<dd>\rPreferred cluster size (in bytes) for the memory object.  This helps to \rdetermine how many pages are transferred in individual data request \rand return messages.\r<p>\r<dt> <var>may_cache_object</var>\r<dd>\rCache indicator.  If true, the kernel can cache data associated with the \rmemory object (keep the memory object active) even if no virtual \rmemory references to it remain.\r</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>memory_object_perf_info</strong> structure\rdefines a memory object's character with respect to performance.\r<h3>NOTES</h3>\r<p>\rSharing cached data among all the clients of a memory object can have a major \rimpact on performance, especially if it can be extended across successive, as \rwell as concurrent, uses.  For example, the memory objects that represent\rprogram images can be used regularly by different programs. \rBy retaining the data \rfor these memory objects in cache, the number of secondary storage accesses \rcan be reduced significantly.\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="MO_get_attributes.html"><strong>memory_object_get_attributes</strong></a>,\r<a href="MO_change_attributes.html"><strong>memory_object_change_attributes</strong></a>,\r<a href="vm_region.html"><strong>vm_region</strong></a>,\r<a href="memory_object_synchronize.html"><strong>memory_object_synchronize</strong></a>,\r<a href="VSD_memory_manager.html"><strong>vm_set_default_memory_manager</strong></a>,\r<a href="vm_msync.html"><strong>vm_msync</strong></a>.\r<p>\rStructures:\r<a href="memory_object_attr_info.html"><strong>memory_object_attr_info</strong></a>.\r