mm/damon: A few fixup with lru_sort

PATCH In review Xin Hao 2 participants 10 messages Aug 18, 2022 – Aug 19, 2022

Subsystems (2)

Memory management DAMON

lore

Share & tools

lore

Xin Hao

author

2022-08-18 10:57 UTC #1 lore raw

PATCH v2 1/2 mm/damon/lru_sort: Move target memory region check to head of func

In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.

Signed-off-by Xin Hao <[email protected]>

---
 mm/damon/lru_sort.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

mm/damon/lru_sort.c +7 -6

index 9de6f00a71c5..ac50dca026f9 100644
@@ -378,6 +378,13 @@ static int damon_lru_sort_apply_parameters(void)
 	unsigned int hot_thres, cold_thres;
 	int err = 0;
 
+	if (monitor_region_start > monitor_region_end)
+		return -EINVAL;
+	if (!monitor_region_start && !monitor_region_end &&
+			!get_monitoring_region(&monitor_region_start,
+				&monitor_region_end))
+		return -EINVAL;
+
 	err = damon_set_attrs(ctx, sample_interval, aggr_interval, 0,
 			min_nr_regions, max_nr_regions);
 	if (err)

@@ -401,12 +408,6 @@ static int damon_lru_sort_apply_parameters(void)
 		return -ENOMEM;
 	damon_add_scheme(ctx, scheme);
 
-	if (monitor_region_start > monitor_region_end)
-		return -EINVAL;
-	if (!monitor_region_start && !monitor_region_end &&
-			!get_monitoring_region(&monitor_region_start,
-				&monitor_region_end))
-		return -EINVAL;
 	addr_range.start = monitor_region_start;
 	addr_range.end = monitor_region_end;
 	return damon_set_regions(target, &addr_range, 1);

Signature · 1 line

2.27.0

SeongJae Park

maintainer

2022-08-18 17:11 UTC #2 lore raw

Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func

Hi Xin,

Quoted 3 lines · On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <[email protected]> wrote:

In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.

The function, 'damon_lru_sort_apply_parameters()', checks validity of parameters and construct the DAMON context one by one. For example, 'damon_set_attrs()' returns an error if the parameters are invalid. So the intended flow is,

1. check DAMON attributes parameters,
2. apply DAMON attributes parameters,
3. check scheme parameters,
4. apply scheme parameters,
5. check target region parameters, and
6. apply target region parameters.

Therefore what this patch does is making the target regions validity check to be done earlier than validity checks of other parameters. There is no special reason to check the region earlier than others. Also, this change makes the flow of the function a little bit weird in my humble opinion, as the flow will be

1. check target region parameters,
2. check DAMON attributes parameters,
3. apply DAMON attributes parameters,
4. check scheme parameters,
5. apply scheme parameters, and
6. apply target region parameters.

So I'd argue this patch seems not really needed, sorry.

Thanks,
SJ

[...]

haoxin

author

2022-08-19 02:12 UTC #3 lore raw

Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func

Quoted 26 lines · SeongJae Park

Hi Xin,
Quoted 3 lines · On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <[email protected]> wrote:
In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.
The function, 'damon_lru_sort_apply_parameters()', checks validity of parameters and construct the DAMON context one by one. For example, 'damon_set_attrs()' returns an error if the parameters are invalid. So the intended flow is,
1. check DAMON attributes parameters,
2. apply DAMON attributes parameters,
3. check scheme parameters,
4. apply scheme parameters,
5. check target region parameters, and
6. apply target region parameters.
Therefore what this patch does is making the target regions validity check to be done earlier than validity checks of other parameters. There is no special reason to check the region earlier than others. Also, this change makes the flow of the function a little bit weird in my humble opinion, as the flow will be

Quoted 6 lines

1. check target region parameters,
2. check DAMON attributes parameters,
3. apply DAMON attributes parameters,
4. check scheme parameters,
5. apply scheme parameters, and
6. apply target region parameters.

Ok, understand what you mean, my fix looks ugly, buy any apply above are not not necessary if one of them checks failed, why not check all fisrt and then apply them, like this:

1. check target region parameters,

2. check DAMON attributes parameters,

3. check scheme parameters,

Quoted 8 lines

So I'd argue this patch seems not really needed, sorry.
Thanks,
SJ
[...]

SeongJae Park

maintainer

2022-08-19 02:28 UTC #4 lore raw

Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func

Hi Xin,

Quoted 39 lines · SeongJae Park

Quoted 26 lines
Hi Xin,
Quoted 3 lines · On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <[email protected]> wrote:
In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.
The function, 'damon_lru_sort_apply_parameters()', checks validity of parameters and construct the DAMON context one by one. For example, 'damon_set_attrs()' returns an error if the parameters are invalid. So the intended flow is,
1. check DAMON attributes parameters,
2. apply DAMON attributes parameters,
3. check scheme parameters,
4. apply scheme parameters,
5. check target region parameters, and
6. apply target region parameters.
Therefore what this patch does is making the target regions validity check to be done earlier than validity checks of other parameters. There is no special reason to check the region earlier than others. Also, this change makes the flow of the function a little bit weird in my humble opinion, as the flow will be
Quoted 6 lines
1. check target region parameters,
2. check DAMON attributes parameters,
3. apply DAMON attributes parameters,
4. check scheme parameters,
5. apply scheme parameters, and
6. apply target region parameters.
Ok, understand what you mean, my fix looks ugly, buy any apply above
are not not necessary if one of them checks failed, why not check all fisrt and then apply them, like this:

Quoted 5 lines

1. check target region parameters,
2. check DAMON attributes parameters,
3. check scheme parameters,

The parameter values could be changed by users after the check, so we should cache those somewhere anyway. In other words, we cache those in the DAMON context. Therefore I think the above works were not totally waste of the time. Also, because the parameters applying functions like 'damon_set_attrs()' does the check and applying of the parameters together, I feel like current flow is natural.

If I'm missing something, please let me know.

Thanks,
SJ

Quoted 10 lines

Quoted 9 lines
So I'd argue this patch seems not really needed, sorry.
Thanks,
SJ
[...]

haoxin

author

2022-08-19 02:48 UTC #5 lore raw

Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func

Quoted 43 lines · SeongJae Park

Hi Xin,
Quoted 41 lines · SeongJae Park
Quoted 26 lines
Hi Xin,
Quoted 3 lines · On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <[email protected]> wrote:
In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.
The function, 'damon_lru_sort_apply_parameters()', checks validity of parameters and construct the DAMON context one by one. For example, 'damon_set_attrs()' returns an error if the parameters are invalid. So the intended flow is,
1. check DAMON attributes parameters,
2. apply DAMON attributes parameters,
3. check scheme parameters,
4. apply scheme parameters,
5. check target region parameters, and
6. apply target region parameters.
Therefore what this patch does is making the target regions validity check to be done earlier than validity checks of other parameters. There is no special reason to check the region earlier than others. Also, this change makes the flow of the function a little bit weird in my humble opinion, as the flow will be
Quoted 6 lines
1. check target region parameters,
2. check DAMON attributes parameters,
3. apply DAMON attributes parameters,
4. check scheme parameters,
5. apply scheme parameters, and
6. apply target region parameters.
Ok, understand what you mean, my fix looks ugly, buy any apply above
are not not necessary if one of them checks failed, why not check all fisrt and then apply them, like this:
1. check target region parameters,
2. check DAMON attributes parameters,

Quoted 7 lines

Quoted 1 line
3. check scheme parameters,
The parameter values could be changed by users after the check, so we should cache those somewhere anyway. In other words, we cache those in the DAMON context. Therefore I think the above works were not totally waste of the time. Also, because the parameters applying functions like 'damon_set_attrs()' does the check and applying of the parameters together, I feel like current flow is natural.

Ok, Thank you for your detailed explain, just keep it. but there still a problem in damon_lru_sort_apply_parameters

if (!monitor_region_start && !monitor_region_end &&
!get_monitoring_region(&monitor_region_start,
&monitor_region_end))

if (!monitor_region_start || !monitor_region_end ||
!get_monitoring_region(&monitor_region_start,
&monitor_region_end))

the '&&' should fix to '||', anyone checks fail, it should return ?

Quoted 1 line

SeongJae Park

maintainer

2022-08-19 04:52 UTC #6 lore raw

Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func

Quoted 60 lines · On Fri, 19 Aug 2022 10:47:58 +0800 haoxin <[email protected]> wrote:

Quoted 43 lines · SeongJae Park
Hi Xin,
Quoted 41 lines · SeongJae Park
Quoted 26 lines
Hi Xin,
Quoted 3 lines · On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <[email protected]> wrote:
In damon_lru_sort_apply_parameters(), if "monitor_region_start" and "monitor_region_end" is not a valid physical address range, There no need to run the remainder codes in it.
The function, 'damon_lru_sort_apply_parameters()', checks validity of parameters and construct the DAMON context one by one. For example, 'damon_set_attrs()' returns an error if the parameters are invalid. So the intended flow is,
1. check DAMON attributes parameters,
2. apply DAMON attributes parameters,
3. check scheme parameters,
4. apply scheme parameters,
5. check target region parameters, and
6. apply target region parameters.
Therefore what this patch does is making the target regions validity check to be done earlier than validity checks of other parameters. There is no special reason to check the region earlier than others. Also, this change makes the flow of the function a little bit weird in my humble opinion, as the flow will be
Quoted 6 lines
1. check target region parameters,
2. check DAMON attributes parameters,
3. apply DAMON attributes parameters,
4. check scheme parameters,
5. apply scheme parameters, and
6. apply target region parameters.
Ok, understand what you mean, my fix looks ugly, buy any apply above
are not not necessary if one of them checks failed, why not check all fisrt and then apply them, like this:
1. check target region parameters,
2. check DAMON attributes parameters,
Quoted 7 lines
Quoted 1 line
3. check scheme parameters,
The parameter values could be changed by users after the check, so we should cache those somewhere anyway. In other words, we cache those in the DAMON context. Therefore I think the above works were not totally waste of the time. Also, because the parameters applying functions like 'damon_set_attrs()' does the check and applying of the parameters together, I feel like current flow is natural.
Ok, Thank you for your detailed explain, just keep it. but there still a problem in damon_lru_sort_apply_parameters
if (!monitor_region_start && !monitor_region_end &&
!get_monitoring_region(&monitor_region_start,
&monitor_region_end))

Quoted 5 lines

if (!monitor_region_start || !monitor_region_end ||
!get_monitoring_region(&monitor_region_start,
&monitor_region_end))
the '&&' should fix to '||', anyone checks fail, it should return ?

No. The code is for setting the monitoring region as the biggest System RAM resource only if the user didn't set both 'monitor_region_start' and 'monitor_region_end'.

Thanks,
SJ

Xin Hao

author

2022-08-18 10:58 UTC #7 lore raw

PATCH v2 2/2 mm/damon/lru_sort: Remove struct of damon_lru_sort_ram_walk_arg

In reply to Xin Hao

The struct of 'damon_lru_sort_ram_walk_arg' is the same with struct of 'damon_addr_range', so, there no need to redefine it, just use struct of 'damon_addr_range' instead.

Signed-off-by Xin Hao <[email protected]>

---
 mm/damon/lru_sort.c | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

mm/damon/lru_sort.c +13 ~~-21~~

index ac50dca026f9..a3674532fa67 100644
@@ -257,18 +257,13 @@ module_param(nr_cold_quota_exceeds, ulong, 0400);
 static struct damon_ctx *ctx;
 static struct damon_target *target;
 
-struct damon_lru_sort_ram_walk_arg {
-	unsigned long start;
-	unsigned long end;
-};
-
 static int walk_system_ram(struct resource *res, void *arg)
 {
-	struct damon_lru_sort_ram_walk_arg *a = arg;
+	struct damon_addr_range *r = arg;
 
-	if (a->end - a->start < resource_size(res)) {
-		a->start = res->start;
-		a->end = res->end;
+	if (r->end - r->start < resource_size(res)) {
+		r->start = res->start;
+		r->end = res->end;
 	}
 	return 0;
 }

@@ -277,16 +272,12 @@ static int walk_system_ram(struct resource *res, void *arg)
  * Find biggest 'System RAM' resource and store its start and end address in
  * @start and @end, respectively.  If no System RAM is found, returns false.
  */
-static bool get_monitoring_region(unsigned long *start, unsigned long *end)
+static bool get_monitoring_region(struct damon_addr_range *range)
 {
-	struct damon_lru_sort_ram_walk_arg arg = {};
-
-	walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram);
-	if (arg.end <= arg.start)
+	walk_system_ram_res(0, ULONG_MAX, range, walk_system_ram);
+	if (range->end <= range->start)
 		return false;
 
-	*start = arg.start;
-	*end = arg.end;
 	return true;
 }

@@ -380,9 +371,12 @@ static int damon_lru_sort_apply_parameters(void)
 
 	if (monitor_region_start > monitor_region_end)
 		return -EINVAL;
-	if (!monitor_region_start && !monitor_region_end &&
-			!get_monitoring_region(&monitor_region_start,
-				&monitor_region_end))
+	if (!monitor_region_end)
+		return -EINVAL;
+
+	addr_range.start = monitor_region_start;
+	addr_range.end = monitor_region_end;
+	if (!get_monitoring_region(&addr_range))
 		return -EINVAL;
 
 	err = damon_set_attrs(ctx, sample_interval, aggr_interval, 0,

@@ -408,8 +402,6 @@ static int damon_lru_sort_apply_parameters(void)
 		return -ENOMEM;
 	damon_add_scheme(ctx, scheme);
 
-	addr_range.start = monitor_region_start;
-	addr_range.end = monitor_region_end;
 	return damon_set_regions(target, &addr_range, 1);
 }

--
2.27.0

SeongJae Park

maintainer

2022-08-18 17:23 UTC #8 lore raw

Re: [PATCH V2 2/2] mm/damon/lru_sort: Remove struct of damon_lru_sort_ram_walk_arg

Hi Xin,

Quoted 3 lines · On Thu, 18 Aug 2022 18:57:32 +0800 Xin Hao <[email protected]> wrote:

The struct of 'damon_lru_sort_ram_walk_arg' is the same with struct of 'damon_addr_range', so, there no need to redefine it, just use struct of 'damon_addr_range' instead.

Reducing code is always good, thanks. However, I think the type of the 'start' and 'end' fields of 'struct damon_addr_range' might be changed in a future. It's very unlikely, though. Also, we might add some more fields to the struct in a future. After all, the purpose of 'struct damon_addr_range' is not saving the 'start' and 'end' fields of 'struct resource'. I'd like to avoid making any possible dependency here, sorry.

Thanks,
SJ

[...]

haoxin

author

2022-08-19 01:57 UTC #9 lore raw

Re: [PATCH V2 2/2] mm/damon/lru_sort: Remove struct of damon_lru_sort_ram_walk_arg

Quoted 9 lines · SeongJae Park

Hi Xin,
Quoted 3 lines · On Thu, 18 Aug 2022 18:57:32 +0800 Xin Hao <[email protected]> wrote:
The struct of 'damon_lru_sort_ram_walk_arg' is the same with struct of 'damon_addr_range', so, there no need to redefine it, just use struct of 'damon_addr_range' instead.
Reducing code is always good, thanks. However, I think the type of the 'start' and 'end' fields of 'struct damon_addr_range' might be changed in a future.

OK, get it.

Quoted 10 lines

It's very unlikely, though. Also, we might add some more fields to the struct in a future. After all, the purpose of 'struct damon_addr_range' is not saving the 'start' and 'end' fields of 'struct resource'. I'd like to avoid making any possible dependency here, sorry.
Thanks,
SJ
[...]