kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
__meminit annotation. No functional change intended.
Signed-off-by: Miaohe Lin <[email protected]>
---
include/linux/compaction.h | 2 +-
include/linux/swap.h | 2 +-
mm/compaction.c | 4 +++-
mm/vmscan.c | 4 +++-
4 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index e94776496049..3dbb7eea96eb 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -99,7 +99,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
int alloc_flags);
extern void __meminit kcompactd_run(int nid);
-extern void __meminit kcompactd_stop(int nid);
+extern void kcompactd_stop(int nid);
extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
#else
diff --git a/include/linux/swap.h b/include/linux/swap.h
index bb5adc604144..c102587b3a86 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -437,7 +437,7 @@ static inline bool node_reclaim_enabled(void)
void check_move_unevictable_folios(struct folio_batch *fbatch);
extern void __meminit kswapd_run(int nid);
-extern void __meminit kswapd_stop(int nid);
+extern void kswapd_stop(int nid);
#ifdef CONFIG_SWAP
diff --git a/mm/compaction.c b/mm/compaction.c
index ea61922a1619..c59244d2ed5a 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -3132,11 +3132,12 @@ void __meminit kcompactd_run(int nid)
}
}
+#ifdef CONFIG_MEMORY_HOTREMOVE
/*
* Called by memory hotplug when all memory in a node is offlined. Caller must
* be holding mem_hotplug_begin/done().
*/
-void __meminit kcompactd_stop(int nid)
+void kcompactd_stop(int nid)
{
struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd;
@@ -3145,6 +3146,7 @@ void __meminit kcompactd_stop(int nid)
NODE_DATA(nid)->kcompactd = NULL;
}
}
+#endif
/*
* It's optimal to keep kcompactd on the same CPUs as their memory, but
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 80e9a222e522..eb4db273bf7e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7897,11 +7897,12 @@ void __meminit kswapd_run(int nid)
pgdat_kswapd_unlock(pgdat);
}
+#ifdef CONFIG_MEMORY_HOTREMOVE
/*
* Called by memory hotplug when all memory in a node is offlined. Caller must
* be holding mem_hotplug_begin/done().
*/
-void __meminit kswapd_stop(int nid)
+void kswapd_stop(int nid)
{
pg_data_t *pgdat = NODE_DATA(nid);
struct task_struct *kswapd;
@@ -7914,6 +7915,7 @@ void __meminit kswapd_stop(int nid)
}
pgdat_kswapd_unlock(pgdat);
}
+#endif
static int __init kswapd_init(void)
{
--
2.33.0
On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote:
> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
> __meminit annotation. No functional change intended.
I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE
is disabled, the linker drops this section (... right?) If it's enabled,
then it gets shunted off into a cold section. So it seems like this
patch strictly makes things worse. But maybe I misunderstood.
On Tue, Aug 08, 2023 at 11:08:36AM +0800, Miaohe Lin wrote:
> On 2023/8/8 10:31, Matthew Wilcox wrote:
> > On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote:
> >> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
> >> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
> >> __meminit annotation. No functional change intended.
> >
> > I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE
> > is disabled, the linker drops this section (... right?) If it's enabled,
>
> When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch:
>
> size mm/compaction.o
> text data bss dec hex filename
> 103164 30873 0 134037 20b95 mm/compaction.o
>
> size mm/vmscan.o
> text data bss dec hex filename
> 158775 49612 64 208451 32e43 mm/vmscan.o
>
> while with this patch:
>
> size mm/compaction.o
> text data bss dec hex filename
> 102915 30865 0 133780 20a94 mm/compaction.o
>
> size mm/vmscan.o
> text data bss dec hex filename
> 158534 49604 64 208202 32d4a mm/vmscan.o
>
> We can reduce each .o by ~250 bytes.
But this is before the linker step! That will be where the meminit
sections get dropped. Assuming they are; I haven't verified. You need
to compare before/after of the vmlinux, not the individual .o files.
On 2023/8/8 10:31, Matthew Wilcox wrote:
> On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote:
>> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
>> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
>> __meminit annotation. No functional change intended.
>
> I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE
> is disabled, the linker drops this section (... right?) If it's enabled,
When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch:
size mm/compaction.o
text data bss dec hex filename
103164 30873 0 134037 20b95 mm/compaction.o
size mm/vmscan.o
text data bss dec hex filename
158775 49612 64 208451 32e43 mm/vmscan.o
while with this patch:
size mm/compaction.o
text data bss dec hex filename
102915 30865 0 133780 20a94 mm/compaction.o
size mm/vmscan.o
text data bss dec hex filename
158534 49604 64 208202 32d4a mm/vmscan.o
We can reduce each .o by ~250 bytes.
> then it gets shunted off into a cold section. So it seems like this
> patch strictly makes things worse. But maybe I misunderstood.
What about add __cold annotation? Something like:
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eb4db273bf7e..e27ffa22c70f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7902,7 +7902,7 @@ void __meminit kswapd_run(int nid)
* Called by memory hotplug when all memory in a node is offlined. Caller must
* be holding mem_hotplug_begin/done().
*/
-void kswapd_stop(int nid)
+void __cold kswapd_stop(int nid)
{
pg_data_t *pgdat = NODE_DATA(nid);
struct task_struct *kswapd;
Thanks.
On Tue, Aug 08, 2023 at 04:16:57AM +0100, Matthew Wilcox wrote:
> On Tue, Aug 08, 2023 at 11:08:36AM +0800, Miaohe Lin wrote:
> > On 2023/8/8 10:31, Matthew Wilcox wrote:
> > > On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote:
> > >> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
> > >> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
> > >> __meminit annotation. No functional change intended.
> > >
> > > I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE
> > > is disabled, the linker drops this section (... right?) If it's enabled,
> >
> > When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch:
> >
> > size mm/compaction.o
> > text data bss dec hex filename
> > 103164 30873 0 134037 20b95 mm/compaction.o
> >
> > size mm/vmscan.o
> > text data bss dec hex filename
> > 158775 49612 64 208451 32e43 mm/vmscan.o
> >
> > while with this patch:
> >
> > size mm/compaction.o
> > text data bss dec hex filename
> > 102915 30865 0 133780 20a94 mm/compaction.o
> >
> > size mm/vmscan.o
> > text data bss dec hex filename
> > 158534 49604 64 208202 32d4a mm/vmscan.o
> >
> > We can reduce each .o by ~250 bytes.
>
> But this is before the linker step! That will be where the meminit
> sections get dropped. Assuming they are; I haven't verified. You need
> to compare before/after of the vmlinux, not the individual .o files.
Ah, found it:
#if defined(CONFIG_MEMORY_HOTPLUG)
#define MEM_KEEP(sec) *(.mem##sec)
#define MEM_DISCARD(sec)
#else
#define MEM_KEEP(sec)
#define MEM_DISCARD(sec) *(.mem##sec)
#endif
in include/asm-generic/vmlinux.lds.h
So yeah, I think this patch is garbage.
On 2023/8/8 11:26, Matthew Wilcox wrote:
> On Tue, Aug 08, 2023 at 04:16:57AM +0100, Matthew Wilcox wrote:
>> On Tue, Aug 08, 2023 at 11:08:36AM +0800, Miaohe Lin wrote:
>>> On 2023/8/8 10:31, Matthew Wilcox wrote:
>>>> On Tue, Aug 08, 2023 at 09:58:31AM +0800, Miaohe Lin wrote:
>>>>> kswapd_stop() and kcompactd_stop() are only called when MEMORY_HOTREMOVE
>>>>> is enabled. So wrap them under CONFIG_MEMORY_HOTREMOVE and further remove
>>>>> __meminit annotation. No functional change intended.
>>>>
>>>> I don't understand why this is an improvement. If CONFIG_MEMORY_HOTREMOVE
>>>> is disabled, the linker drops this section (... right?) If it's enabled,
>>>
>>> When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch:
>>>
>>> size mm/compaction.o
>>> text data bss dec hex filename
>>> 103164 30873 0 134037 20b95 mm/compaction.o
>>>
>>> size mm/vmscan.o
>>> text data bss dec hex filename
>>> 158775 49612 64 208451 32e43 mm/vmscan.o
>>>
>>> while with this patch:
>>>
>>> size mm/compaction.o
>>> text data bss dec hex filename
>>> 102915 30865 0 133780 20a94 mm/compaction.o
>>>
>>> size mm/vmscan.o
>>> text data bss dec hex filename
>>> 158534 49604 64 208202 32d4a mm/vmscan.o
>>>
>>> We can reduce each .o by ~250 bytes.
>>
>> But this is before the linker step! That will be where the meminit
>> sections get dropped. Assuming they are; I haven't verified. You need
>> to compare before/after of the vmlinux, not the individual .o files.
When CONFIG_MEMORY_HOTREMOVE is disabled, without patch:
size vmlinux
text data bss dec hex filename
70648396 21668938 17985540 110302874 693169a vmlinux
while with patch:
size vmlinux
text data bss dec hex filename
70648128 21668938 17985540 110302606 693158e vmlinux
vmlinux is still reduced by 268 bytes.
>
> Ah, found it:
>
> #if defined(CONFIG_MEMORY_HOTPLUG)
> #define MEM_KEEP(sec) *(.mem##sec)
> #define MEM_DISCARD(sec)
> #else
> #define MEM_KEEP(sec)
> #define MEM_DISCARD(sec) *(.mem##sec)
> #endif
>
> in include/asm-generic/vmlinux.lds.h
When CONFIG_MEMORY_HOTREMOVE is disabled, without this patch, kswapd_stop() and kcompactd_stop()
are dropped after system init.
But no insist in this patch.
Thanks for your comment.