mm: slub: make slab_sysfs_init() a late_initcall

Currently, slab_sysfs_init() is an __initcall aka device_initcall. It
is rather time-consuming; on my board it takes around 11ms. That's
about 1% of the time budget I have from U-Boot letting go and until
linux must assume responsibility of keeping the external watchdog
happy.

There's no particular reason this would need to run at device_initcall
time, so instead make it a late_initcall to allow vital functionality
to get started a bit sooner.

This actually ends up winning more than just those 11ms, because the
slab caches that get created during other device_initcalls (and before
my watchdog device gets probed) now don't end up doing the somewhat
expensive sysfs_slab_add() themselves. Some example lines (with
initcall_debug set) before/after:

initcall ext4_init_fs+0x0/0x1ac returned 0 after 1386 usecs
initcall journal_init+0x0/0x138 returned 0 after 517 usecs
initcall init_fat_fs+0x0/0x68 returned 0 after 294 usecs

initcall ext4_init_fs+0x0/0x1ac returned 0 after 240 usecs
initcall journal_init+0x0/0x138 returned 0 after 32 usecs
initcall init_fat_fs+0x0/0x68 returned 0 after 18 usecs

Altogether, this means I now get to petting the watchdog around 17ms
sooner. [Of course, the time the other initcalls save is instead spent
in slab_sysfs_init(), which goes from 11ms to 16ms, so there's no
overall change in boot time.]

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

This commit is contained in:

Rasmus Villemoes

2022-09-30 12:27:12 +02:00

committed by

Vlastimil Babka

parent 979857ea2d

commit 1a5ad30b89

1 changed files with 1 additions and 2 deletions

									
										3

mm/slub.c

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				@ -6049,8 +6049,7 @@ static int __init slab_sysfs_init(void)

					mutex_unlock(&slab_mutex);

					return 0;

				}

				__initcall(slab_sysfs_init);

				late_initcall(slab_sysfs_init);

				#endif /* CONFIG_SYSFS */

				#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)

mm: slub: make slab_sysfs_init() a late_initcall

3 mm/slub.c Unescape Escape View File

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mm/slub.c

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