arch/x86/resctrl.rst

57 pseudo-locking is a unique way of using cache control to "pin" or
128 			      Corresponding region is pseudo-locked. No
332 	When the resource group is in pseudo-locked mode this file will
334 	pseudo-locked region.
356 	cache pseudo-locked region is created by first writing
357 	"pseudo-locksetup" to the "mode" file before writing the cache
358 	pseudo-locked region's schemata to the resource group's "schemata"
359 	file. On successful pseudo-locked region creation the mode will
360 	automatically change to "pseudo-locked".
694 application can fill. Cache pseudo-locking builds on the fact that a
696 allocated area on a cache hit. With cache pseudo-locking, data can be
699 pseudo-locked memory is made accessible to user space where an
703 The creation of a cache pseudo-locked region is triggered by a request
705 to be pseudo-locked. The cache pseudo-locked region is created as follows:
708   from the user of the cache region that will contain the pseudo-locked
711   while the pseudo-locked region exists.
719   pseudo-locked region is protected as long as its CBM does not appear in
720   any CAT allocation. Even though the cache pseudo-locked region will from
722   any CLOS will be able to access the memory in the pseudo-locked region since
727 Cache pseudo-locking increases the probability that data will remain
733 pseudo-locked region creation.
735 It is required that an application using a pseudo-locked region runs
737 with the cache on which the pseudo-locked region resides. A sanity check
738 within the code will not allow an application to map pseudo-locked memory
740 pseudo-locked region resides. The sanity check is only done during the
747    of cache that should be dedicated to pseudo-locking. At this time an
751    pseudo-locked memory into its address space.
755 A pseudo-locked region is created using the resctrl interface as follows:
758 2) Change the new resource group's mode to "pseudo-locksetup" by writing
759    "pseudo-locksetup" to the "mode" file.
760 3) Write the schemata of the pseudo-locked region to the "schemata" file. All
764 On successful pseudo-locked region creation the "mode" file will contain
765 "pseudo-locked" and a new character device with the same name as the resource
767 by user space in order to obtain access to the pseudo-locked memory region.
769 An example of cache pseudo-locked region creation and usage can be found below.
773 The pseudo-locking debugging interface is enabled by default (if
777 location is present in the cache. The pseudo-locking debugging interface uses
779 the pseudo-locked region:
783    example below). In this test the pseudo-locked region is traversed at
791 When a pseudo-locked region is created a new debugfs directory is created for
794 measurement of the pseudo-locked region depends on the number written to this
815 In this example a pseudo-locked region named "newlock" was created. Here is
849 In this example a pseudo-locked region named "newlock" was created on the L2
1083 Ensure that there are bits available that can be pseudo-locked, since only
1084 unused bits can be pseudo-locked the bits to be pseudo-locked needs to be
1093 Create a new resource group that will be associated with the pseudo-locked
1094 region, indicate that it will be used for a pseudo-locked region, and
1095 configure the requested pseudo-locked region capacity bitmask::
1098   # echo pseudo-locksetup > newlock/mode
1101 On success the resource group's mode will change to pseudo-locked, the
1102 bit_usage will reflect the pseudo-locked region, and the character device
1103 exposing the pseudo-locked region will exist::
1106   pseudo-locked
1115   * Example code to access one page of pseudo-locked cache region
1128   * cores associated with the pseudo-locked region. Here the cpu
1165     /* Application interacts with pseudo-locked memory @mapping */