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ANDROID: mm: lru_cache_disable skips lru cache drainnig

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lru_cache_disable is not trivial cost since it should run work
from every cores in the system. Thus, repeated call of the
function whenever alloc_contig_range in the cma's allocation loop
is called is expensive.

This patch makes the lru_cache_disable smarter in that it will
not run __lru_add_drain_all since it knows the cache was already
disabled by someone else.
With that, user of alloc_contig_range can disable the lru cache
in advance in their context so that subsequent alloc_contig_range
for user's operation will avoid the costly function call.

Bug: 313795505
Change-Id: Icbb0e6dbf74644d45f562fd1d845888ca1f1f347
Signed-off-by: Richard Chang <richardycc@google.com>
(cherry picked from commit 816567b17866ca3f9a11e670bd52c82335cbb448)
This commit is contained in:
Richard Chang 2023-11-29 06:41:13 +00:00 committed by Treehugger Robot
parent 0de2f42977
commit 5723833390
1 changed files with 9 additions and 1 deletions
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10
mm/swap.c
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@ -933,6 +933,7 @@ void lru_add_drain_all(void)
#endif /* CONFIG_SMP */ #endif /* CONFIG_SMP */
atomic_t lru_disable_count = ATOMIC_INIT(0); atomic_t lru_disable_count = ATOMIC_INIT(0);
EXPORT_SYMBOL_GPL(lru_disable_count);
/* /*
* lru_cache_disable() needs to be called before we start compiling * lru_cache_disable() needs to be called before we start compiling
@ -944,7 +945,12 @@ atomic_t lru_disable_count = ATOMIC_INIT(0);
*/ */
void lru_cache_disable(void) void lru_cache_disable(void)
{ {
atomic_inc(&lru_disable_count); /*
* If someone is already disabled lru_cache, just return with
* increasing the lru_disable_count.
*/
if (atomic_inc_not_zero(&lru_disable_count))
return;
/* /*
* Readers of lru_disable_count are protected by either disabling * Readers of lru_disable_count are protected by either disabling
* preemption or rcu_read_lock: * preemption or rcu_read_lock:
@ -964,7 +970,9 @@ void lru_cache_disable(void)
#else #else
lru_add_and_bh_lrus_drain(); lru_add_and_bh_lrus_drain();
#endif #endif
atomic_inc(&lru_disable_count);
} }
EXPORT_SYMBOL_GPL(lru_cache_disable);
/** /**
* release_pages - batched put_page() * release_pages - batched put_page()