Hi Park:
On Wed, 10 Nov 2021 20:13:14 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote:In patch "mm/damon: add a tracepoint", it adds a tracepoint for DAMON, it can monitor each region for each aggregation interval, Now the region add a new 'age' variable, some primitive would calculate the priority of each region as a weight, there put it into tracepoint, so we can easily track the change of its value through perf or damon-tools.DAMON calculates the age using the address range and nr_accesses of the region, which are already in the tracepoint. In other words, user space can calculate the age on their own. Therefore I thought putting age in the tracepoint as adding unnecessary information, at the moment of the implementation. Of course, I would missing some use cases that need this information in the tracepoint. Furthermore, adding just one more value in the tracepoint wouldn't incur a real issue. But, I'd like to know why this is necessary and how much benefit it provides. Xin, could you please share that?
I think these two variables nr_access & age have different
meanings, the nr_access only reflect the
period of sample_interval, We may be able to get the change of age through continuous long-term sampling,
But I think this is not very convenient.
We only need to observe the change of age value a small number of
times to replace the continue sampling of the region.
For example, age has been increasing to 141, but nr_access shows
a value of 0 at a certain time. Through this，we can
conclude that the region has a very low nr_access value for a
long time.
This datas that i used perf tool to record & script
kdamond.0 8282 [007] 664.187237:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 305254400-597266432: 0 140
kdamond.0 8282 [007] 664.187237:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 597266432-900239360: 0 140
kdamond.0 8282 [007] 664.187237:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 900239360-980148224: 0 140
kdamond.0 8282 [007] 664.187238: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281471544459264-281471789129728: 0 1
kdamond.0 8282 [007] 664.187238: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281471789129728-281472066732032: 0 0
kdamond.0 8282 [007] 664.187238: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472066732032-281472281972736: 0 1
kdamond.0 8282 [007] 664.187239: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472281972736-281472346124288: 1 0
kdamond.0 8282 [007] 664.187239: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472346124288-281472379187200: 0 1
kdamond.0 8282 [007] 664.187239: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472379187200-281472678154240: 1 0
kdamond.0 8282 [007] 664.187239: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472678154240-281472951209984: 1 0
kdamond.0 8282 [007] 664.187240: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472951209984-281473069228032: 2 0
kdamond.0 8282 [007] 664.187240: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473069228032-281473299972096: 0 1
kdamond.0 8282 [007] 664.187241: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473299972096-281473603727360: 0 0
kdamond.0 8282 [007] 664.187241: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473603727360-281473611063296: 0 5
kdamond.0 8282 [007] 664.187242: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281474851557376-281474851692544: 0 140
kdamond.0 8282 [007] 664.287642:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 4194304-305254400: 0 141
kdamond.0 8282 [007] 664.287643:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 305254400-597266432: 0 141
kdamond.0 8282 [007] 664.287643:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 597266432-900239360: 0 141
kdamond.0 8282 [007] 664.287650:
damon:damon_aggregated: target_id=18446462650354140800
nr_regions=16 900239360-980148224: 0 141
kdamond.0 8282 [007] 664.287650: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281471544459264-281471789129728: 0 2
kdamond.0 8282 [007] 664.287651: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281471789129728-281472066732032: 0 1
kdamond.0 8282 [007] 664.287651: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472066732032-281472349429760: 0 0
kdamond.0 8282 [007] 664.287651: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472349429760-281472588464128: 0 0
kdamond.0 8282 [007] 664.287652: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472588464128-281472678154240: 0 0
kdamond.0 8282 [007] 664.287652: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472678154240-281472951209984: 0 0
kdamond.0 8282 [007] 664.287652: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281472951209984-281473092300800: 1 0
kdamond.0 8282 [007] 664.287653: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473092300800-281473299972096: 0 2
kdamond.0 8282 [007] 664.287654: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473299972096-281473421471744: 0 1
kdamond.0 8282 [007] 664.287654: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473421471744-281473603727360: 2 0
kdamond.0 8282 [007] 664.287654: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281473603727360-281473611063296: 0 6
kdamond.0 8282 [007] 664.287655: damon:damon_aggregated:
target_id=18446462650354140800 nr_regions=16
281474851557376-281474851692544: 0 141
Thanks, SJSigned-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx> --- include/trace/events/damon.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h index 2f422f4f1fb9..99ffa601e351 100644 --- a/include/trace/events/damon.h +++ b/include/trace/events/damon.h @@ -22,6 +22,7 @@ TRACE_EVENT(damon_aggregated, __field(unsigned long, start) __field(unsigned long, end) __field(unsigned int, nr_accesses) + __field(unsigned int, age) ), TP_fast_assign( @@ -30,11 +31,13 @@ TRACE_EVENT(damon_aggregated, __entry->start = r->ar.start; __entry->end = r->ar.end; __entry->nr_accesses = r->nr_accesses; + __entry->age = r->age; ), - TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u", + TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u %u", __entry->target_id, __entry->nr_regions, - __entry->start, __entry->end, __entry->nr_accesses) + __entry->start, __entry->end, + __entry->nr_accesses, __entry->age) ); #endif /* _TRACE_DAMON_H */ -- 2.31.0
-- Best Regards! Xin Hao
