[PATCH V1 0/2] mm/damon: Do some small changes

[PATCH V1 0/2] mm/damon: Do some small changes

[Xin Hao]

These two patches are mainly to do some small changes.

Xin Hao (2):
  mm/damon: Unified access_check function naming rules
  mm/damon: Add 'age' of region tracepoint support

 include/trace/events/damon.h | 7 +++++--
 mm/damon/vaddr.c             | 8 ++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

--
2.31.0

[PATCH V1 1/2] mm/damon: Unified access_check function naming rules

[Xin Hao]

In damon/paddr.c file, two functions names start with underscore,
	static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
			struct damon_region *r)
	static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
			struct damon_region *r)
In damon/vaddr.c file, there are also two functions with the same function,
	static void damon_va_prepare_access_check(struct damon_ctx *ctx,
			struct mm_struct *mm, struct damon_region *r)
	static void damon_va_check_access(struct damon_ctx *ctx,
			struct mm_struct *mm, struct damon_region *r)

It makes sense to keep consistent, and it is not easy to be confused with
the function that call them.

Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
---
 mm/damon/vaddr.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 35fe49080ee9..905e0fc8a8ec 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -409,7 +409,7 @@ static void damon_va_mkold(struct mm_struct *mm, unsigned long addr)
  * Functions for the access checking of the regions
  */
 
-static void damon_va_prepare_access_check(struct damon_ctx *ctx,
+static void __damon_va_prepare_access_check(struct damon_ctx *ctx,
 			struct mm_struct *mm, struct damon_region *r)
 {
 	r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
@@ -428,7 +428,7 @@ void damon_va_prepare_access_checks(struct damon_ctx *ctx)
 		if (!mm)
 			continue;
 		damon_for_each_region(r, t)
-			damon_va_prepare_access_check(ctx, mm, r);
+			__damon_va_prepare_access_check(ctx, mm, r);
 		mmput(mm);
 	}
 }
@@ -514,7 +514,7 @@ static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
  * mm	'mm_struct' for the given virtual address space
  * r	the region to be checked
  */
-static void damon_va_check_access(struct damon_ctx *ctx,
+static void __damon_va_check_access(struct damon_ctx *ctx,
 			       struct mm_struct *mm, struct damon_region *r)
 {
 	static struct mm_struct *last_mm;
@@ -550,7 +550,7 @@ unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
 		if (!mm)
 			continue;
 		damon_for_each_region(r, t) {
-			damon_va_check_access(ctx, mm, r);
+			__damon_va_check_access(ctx, mm, r);
 			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
 		}
 		mmput(mm);
-- 
2.31.0

[PATCH V1 2/2] mm/damon: Add 'age' of region tracepoint support

[Xin Hao]

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.

Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
---
 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

Re: [PATCH V1 1/2] mm/damon: Unified access_check function naming rules

[SeongJae Park]

On Wed, 10 Nov 2021 20:13:13 +0800 Xin Hao <xhao@linux.alibaba.com> wrote:

> In damon/paddr.c file, two functions names start with underscore,
> 	static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
> 			struct damon_region *r)
> 	static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
> 			struct damon_region *r)
> In damon/vaddr.c file, there are also two functions with the same function,
> 	static void damon_va_prepare_access_check(struct damon_ctx *ctx,
> 			struct mm_struct *mm, struct damon_region *r)
> 	static void damon_va_check_access(struct damon_ctx *ctx,
> 			struct mm_struct *mm, struct damon_region *r)
> 
> It makes sense to keep consistent, and it is not easy to be confused with
> the function that call them.
> 
> Signed-off-by: Xin Hao <xhao@linux.alibaba.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH V1 2/2] mm/damon: Add 'age' of region tracepoint support

[SeongJae Park]

On Wed, 10 Nov 2021 20:13:14 +0800 Xin Hao <xhao@linux.alibaba.com> 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?


Thanks,
SJ

> 
> Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
> ---
>  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