* [PATCH] mm/compaction: Remove some useless code in compact_zone()
@ 2020-10-14 7:23 yanfei.xu
2020-10-14 12:28 ` David Hildenbrand
0 siblings, 1 reply; 4+ messages in thread
From: yanfei.xu @ 2020-10-14 7:23 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel
From: Yanfei Xu <yanfei.xu@windriver.com>
start_pfn has been declared at the begin of compact_zone(), it's
no need to declare it again. And remove an useless semicolon.
Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
---
mm/compaction.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 176dcded298e..5e69c1f94d96 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2272,7 +2272,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
int err;
- unsigned long start_pfn = cc->migrate_pfn;
+ start_pfn = cc->migrate_pfn;
/*
* Avoid multiple rescans which can happen if a page cannot be
@@ -2309,7 +2309,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
case ISOLATE_SUCCESS:
update_cached = false;
last_migrated_pfn = start_pfn;
- ;
}
err = migrate_pages(&cc->migratepages, compaction_alloc,
--
2.18.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/compaction: Remove some useless code in compact_zone()
2020-10-14 7:23 [PATCH] mm/compaction: Remove some useless code in compact_zone() yanfei.xu
@ 2020-10-14 12:28 ` David Hildenbrand
2020-10-16 15:05 ` Vlastimil Babka
0 siblings, 1 reply; 4+ messages in thread
From: David Hildenbrand @ 2020-10-14 12:28 UTC (permalink / raw)
To: yanfei.xu, akpm; +Cc: linux-mm, linux-kernel
On 14.10.20 09:23, yanfei.xu@windriver.com wrote:
> From: Yanfei Xu <yanfei.xu@windriver.com>
>
> start_pfn has been declared at the begin of compact_zone(), it's
> no need to declare it again. And remove an useless semicolon.
>
> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
> ---
> mm/compaction.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 176dcded298e..5e69c1f94d96 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -2272,7 +2272,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
>
> while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
> int err;
> - unsigned long start_pfn = cc->migrate_pfn;
> + start_pfn = cc->migrate_pfn;
There is a user in
trace_mm_compaction_end(start_pfn, cc->migrate_pfn, cc->free_pfn,
end_pfn, sync, ret);
we would now trace a different value, no?
>
> /*
> * Avoid multiple rescans which can happen if a page cannot be
> @@ -2309,7 +2309,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
> case ISOLATE_SUCCESS:
> update_cached = false;
> last_migrated_pfn = start_pfn;
> - ;
Huh, how does something like that happen :)
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/compaction: Remove some useless code in compact_zone()
2020-10-14 12:28 ` David Hildenbrand
@ 2020-10-16 15:05 ` Vlastimil Babka
2020-10-19 7:32 ` Xu, Yanfei
0 siblings, 1 reply; 4+ messages in thread
From: Vlastimil Babka @ 2020-10-16 15:05 UTC (permalink / raw)
To: David Hildenbrand, yanfei.xu, akpm; +Cc: linux-mm, linux-kernel
On 10/14/20 2:28 PM, David Hildenbrand wrote:
> On 14.10.20 09:23, yanfei.xu@windriver.com wrote:
>> From: Yanfei Xu <yanfei.xu@windriver.com>
>>
>> start_pfn has been declared at the begin of compact_zone(), it's
>> no need to declare it again. And remove an useless semicolon.
>>
>> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
>> ---
>> mm/compaction.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index 176dcded298e..5e69c1f94d96 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -2272,7 +2272,7 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
>>
>> while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
>> int err;
>> - unsigned long start_pfn = cc->migrate_pfn;
>> + start_pfn = cc->migrate_pfn;
>
> There is a user in
>
> trace_mm_compaction_end(start_pfn, cc->migrate_pfn, cc->free_pfn,
> end_pfn, sync, ret);
>
> we would now trace a different value, no?
Agreed. We should rather rename the while-local one to avoid confusion.
Something like "iteration_start_pfn" ?
>>
>> /*
>> * Avoid multiple rescans which can happen if a page cannot be
>> @@ -2309,7 +2309,6 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
>> case ISOLATE_SUCCESS:
>> update_cached = false;
>> last_migrated_pfn = start_pfn;
>> - ;
>
> Huh, how does something like that happen :)
Looks like "case ISOLATE_SUCCESS:" used to be an empty implementation, then
statements got added, but semicolon not removed.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/compaction: Remove some useless code in compact_zone()
2020-10-16 15:05 ` Vlastimil Babka
@ 2020-10-19 7:32 ` Xu, Yanfei
0 siblings, 0 replies; 4+ messages in thread
From: Xu, Yanfei @ 2020-10-19 7:32 UTC (permalink / raw)
To: Vlastimil Babka, David Hildenbrand, akpm; +Cc: linux-mm, linux-kernel
On 10/16/20 11:05 PM, Vlastimil Babka wrote:
> On 10/14/20 2:28 PM, David Hildenbrand wrote:
>> On 14.10.20 09:23, yanfei.xu@windriver.com wrote:
>>> From: Yanfei Xu <yanfei.xu@windriver.com>
>>>
>>> start_pfn has been declared at the begin of compact_zone(), it's
>>> no need to declare it again. And remove an useless semicolon.
>>>
>>> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com>
>>> ---
>>> mm/compaction.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/mm/compaction.c b/mm/compaction.c
>>> index 176dcded298e..5e69c1f94d96 100644
>>> --- a/mm/compaction.c
>>> +++ b/mm/compaction.c
>>> @@ -2272,7 +2272,7 @@ compact_zone(struct compact_control *cc, struct
>>> capture_control *capc)
>>>
>>> while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
>>> int err;
>>> - unsigned long start_pfn = cc->migrate_pfn;
>>> + start_pfn = cc->migrate_pfn;
>>
>> There is a user in
>>
>> trace_mm_compaction_end(start_pfn, cc->migrate_pfn, cc->free_pfn,
>> end_pfn, sync, ret);
>>
>> we would now trace a different value, no?
>
> Agreed. We should rather rename the while-local one to avoid confusion.
> Something like "iteration_start_pfn" ?
>
Thank you, David and Vlastimil, for pointing out the impact to the
tracepoint. I think "iteration_start_pfn" is appropriate and will send V2.
>>>
>>> /*
>>> * Avoid multiple rescans which can happen if a page cannot be
>>> @@ -2309,7 +2309,6 @@ compact_zone(struct compact_control *cc, struct
>>> capture_control *capc)
>>> case ISOLATE_SUCCESS:
>>> update_cached = false;
>>> last_migrated_pfn = start_pfn;
>>> - ;
>>
>> Huh, how does something like that happen :)
>
> Looks like "case ISOLATE_SUCCESS:" used to be an empty implementation,
> then statements got added, but semicolon not removed.
Yup, this case used to be an empty.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-10-14 7:23 [PATCH] mm/compaction: Remove some useless code in compact_zone() yanfei.xu
2020-10-14 12:28 ` David Hildenbrand
2020-10-16 15:05 ` Vlastimil Babka
2020-10-19 7:32 ` Xu, Yanfei
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