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.
