Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying.
From: Michal Hocko <mhocko@suse.com>
Date: 2016-12-12 13:19:13
Subsystem:
memory management, memory management - page allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Linus Torvalds
On Mon 12-12-16 13:55:35, Michal Hocko wrote:
On Mon 12-12-16 21:12:06, Tetsuo Handa wrote:quoted
Michal Hocko wrote:
[...]
quoted
quoted
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I think this warn_alloc() is too much noise. When something went wrong, multiple instances of Thread-2 tend to call warn_alloc() concurrently. We don't need to report similar memory information.That is why we have ratelimitting. It is needs a better tunning then just let's do it.I think that calling show_mem() once per a series of warn_alloc() threads is sufficient. Since the amount of output by dump_stack() and that by show_mem() are nearly equals, we can save nearly 50% of output if we manage to avoid the same show_mem() calls.I do not mind such an update. Again, that is what we have the ratelimitting for. The fact that it doesn't throttle properly means that we should tune its parameters.
What about the following? Does this help? ---
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c52268786027..54348e5a5377 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -3003,9 +3003,12 @@ static inline bool should_suppress_show_mem(void) return ret; } -static DEFINE_RATELIMIT_STATE(nopage_rs, - DEFAULT_RATELIMIT_INTERVAL, - DEFAULT_RATELIMIT_BURST); +/* + * Do not swamp logs with allocation failures details + * Once per second should be more than enough to get an + * overview what is going on + */ +static DEFINE_RATELIMIT_STATE(nopage_rs, HZ, 1); void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) {
@@ -3013,7 +3016,7 @@ void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) struct va_format vaf; va_list args; - if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs) || + if ((gfp_mask & __GFP_NOWARN) || debug_guardpage_minorder() > 0) return;
@@ -3040,7 +3043,7 @@ void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) pr_cont(", mode:%#x(%pGg)\n", gfp_mask, &gfp_mask); dump_stack(); - if (!should_suppress_show_mem()) + if (!should_suppress_show_mem() || __ratelimit(&nopage_rs)) show_mem(filter); }
--
Michal Hocko
SUSE Labs
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