Commit d896073f authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

mm/damon/core: add more comments for nr_accesses 

The comment on struct damon_region about nr_accesses field looks not
sufficient.  Many people actually used to ask what nr_accesses mean.
There is more detailed explanation of the mechanism on the comment for
struct damon_attrs, but it is also ambiguous, as it doesn't specify the
name of the counter for aggregating the access check results.  Make
those more detailed.

Link: https://lkml.kernel.org/r/20230907022929.91361-10-sj@kernel.org


Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 27e68c4b

include/linux/damon.h

+12 −7
Original line number Diff line number Diff line
@@ -43,6 +43,10 @@ struct damon_addr_range { 
 * @list:		List head for siblings.

 * @age:		Age of this region.

 *

 * @nr_accesses is reset to zero for every &damon_attrs->aggr_interval and be

 * increased for every &damon_attrs->sample_interval if an access to the region

 * during the last sampling interval is found.

 *

 * @age is initially zero, increased for each aggregation interval, and reset

 * to zero again if the access frequency is significantly changed.  If two

 * regions are merged into a new region, both @nr_accesses and @age of the new
@@ -472,13 +476,14 @@ struct damon_callback { 
 *				regions.

 *

 * For each @sample_interval, DAMON checks whether each region is accessed or

 * not.  It aggregates and keeps the access information (number of accesses to

 * each region) for @aggr_interval time.  DAMON also checks whether the target

 * memory regions need update (e.g., by ``mmap()`` calls from the application,

 * in case of virtual memory monitoring) and applies the changes for each

 * @ops_update_interval.  All time intervals are in micro-seconds.

 * Please refer to &struct damon_operations and &struct damon_callback for more

 * detail.

 * not during the last @sample_interval.  If such access is found, DAMON

 * aggregates the information by increasing &damon_region->nr_accesses for

 * @aggr_interval time.  For each @aggr_interval, the count is reset.  DAMON

 * also checks whether the target memory regions need update (e.g., by

 * ``mmap()`` calls from the application, in case of virtual memory monitoring)

 * and applies the changes for each @ops_update_interval.  All time intervals

 * are in micro-seconds.  Please refer to &struct damon_operations and &struct

 * damon_callback for more detail.

 */

struct damon_attrs {

	unsigned long sample_interval;