* [PATCH 0/1] mm: setting of min_free_kbytes
@ 2016-04-12 19:54 ` Jason Baron
0 siblings, 0 replies; 8+ messages in thread
From: Jason Baron @ 2016-04-12 19:54 UTC (permalink / raw)
To: akpm, kirill.shutemov
Cc: rientjes, aarcange, mgorman, mhocko, hannes, vbabka, linux-mm,
linux-kernel
Hi,
While updating a workload to a 4.1 kernel (from 3.14), I found that
min_free_kbytes was automatically set to 11365, whereas on 3.14 it was
67584. This is caused by a change to how min_free_kbytes is set when
CONFIG_TRANSPARENT_HUGEPAGE=y, which is detailed in the patch that
follows.
I was wondering as well if the setting of min_free_kbytes could be
improved in the following cases while looking at this code:
1) memory hotplug
we call init_per_zone_wmark_min() but not
set_recommended_min_free_kbytes() (for hugepages)
2) when khugepaged is stopped
Do we want to undo any settings thath khugepaged has done in that
case to restore the default settings
Thanks,
-Jason
Jason Baron (1):
mm: update min_free_kbytes from khugepaged after core initialization
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--
2.6.1
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 0/1] mm: setting of min_free_kbytes
@ 2016-04-12 19:54 ` Jason Baron
0 siblings, 0 replies; 8+ messages in thread
From: Jason Baron @ 2016-04-12 19:54 UTC (permalink / raw)
To: akpm, kirill.shutemov
Cc: rientjes, aarcange, mgorman, mhocko, hannes, vbabka, linux-mm,
linux-kernel
Hi,
While updating a workload to a 4.1 kernel (from 3.14), I found that
min_free_kbytes was automatically set to 11365, whereas on 3.14 it was
67584. This is caused by a change to how min_free_kbytes is set when
CONFIG_TRANSPARENT_HUGEPAGE=y, which is detailed in the patch that
follows.
I was wondering as well if the setting of min_free_kbytes could be
improved in the following cases while looking at this code:
1) memory hotplug
we call init_per_zone_wmark_min() but not
set_recommended_min_free_kbytes() (for hugepages)
2) when khugepaged is stopped
Do we want to undo any settings thath khugepaged has done in that
case to restore the default settings
Thanks,
-Jason
Jason Baron (1):
mm: update min_free_kbytes from khugepaged after core initialization
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--
2.6.1
--
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^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
2016-04-12 19:54 ` Jason Baron
@ 2016-04-12 19:54 ` Jason Baron
-1 siblings, 0 replies; 8+ messages in thread
From: Jason Baron @ 2016-04-12 19:54 UTC (permalink / raw)
To: akpm, kirill.shutemov
Cc: rientjes, aarcange, mgorman, mhocko, hannes, vbabka, linux-mm,
linux-kernel
Khugepaged attempts to raise min_free_kbytes if its set too low. However,
on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
then the mm 'core' over-rides min_free_kbytes after from
init_per_zone_wmark_min(), via a module_init() call.
Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
it occurred after the core initialization), however this was removed when
the initialization of min_free_kbytes was integrated into the starting of
the khugepaged thread.
The fix here is simply to invoke the core initialization using a
core_initcall() instead of module_init(), such that the previous
initialization ordering is restored. I didn't restore the late_initcall()
since start_stop_khugepaged() already sets min_free_kbytes via
set_recommended_min_free_kbytes().
This was noticed when we had a number of page allocation failures when
moving a workload to a kernel with this new initialization ordering. On an
8GB system this restores min_free_kbytes back to 67584 from 11365 when
CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 59de90d5d3a3..c1069efcc4d7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6485,7 +6485,7 @@ int __meminit init_per_zone_wmark_min(void)
setup_per_zone_inactive_ratio();
return 0;
}
-module_init(init_per_zone_wmark_min)
+core_initcall(init_per_zone_wmark_min)
/*
* min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
--
2.6.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
@ 2016-04-12 19:54 ` Jason Baron
0 siblings, 0 replies; 8+ messages in thread
From: Jason Baron @ 2016-04-12 19:54 UTC (permalink / raw)
To: akpm, kirill.shutemov
Cc: rientjes, aarcange, mgorman, mhocko, hannes, vbabka, linux-mm,
linux-kernel
Khugepaged attempts to raise min_free_kbytes if its set too low. However,
on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
then the mm 'core' over-rides min_free_kbytes after from
init_per_zone_wmark_min(), via a module_init() call.
Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
it occurred after the core initialization), however this was removed when
the initialization of min_free_kbytes was integrated into the starting of
the khugepaged thread.
The fix here is simply to invoke the core initialization using a
core_initcall() instead of module_init(), such that the previous
initialization ordering is restored. I didn't restore the late_initcall()
since start_stop_khugepaged() already sets min_free_kbytes via
set_recommended_min_free_kbytes().
This was noticed when we had a number of page allocation failures when
moving a workload to a kernel with this new initialization ordering. On an
8GB system this restores min_free_kbytes back to 67584 from 11365 when
CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 59de90d5d3a3..c1069efcc4d7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6485,7 +6485,7 @@ int __meminit init_per_zone_wmark_min(void)
setup_per_zone_inactive_ratio();
return 0;
}
-module_init(init_per_zone_wmark_min)
+core_initcall(init_per_zone_wmark_min)
/*
* min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so
--
2.6.1
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
2016-04-12 19:54 ` Jason Baron
@ 2016-04-13 10:36 ` Kirill A. Shutemov
-1 siblings, 0 replies; 8+ messages in thread
From: Kirill A. Shutemov @ 2016-04-13 10:36 UTC (permalink / raw)
To: Jason Baron
Cc: akpm, kirill.shutemov, rientjes, aarcange, mgorman, mhocko,
hannes, vbabka, linux-mm, linux-kernel
On Tue, Apr 12, 2016 at 03:54:37PM -0400, Jason Baron wrote:
> Khugepaged attempts to raise min_free_kbytes if its set too low. However,
> on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
> then the mm 'core' over-rides min_free_kbytes after from
> init_per_zone_wmark_min(), via a module_init() call.
>
> Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
> it occurred after the core initialization), however this was removed when
> the initialization of min_free_kbytes was integrated into the starting of
> the khugepaged thread.
>
> The fix here is simply to invoke the core initialization using a
> core_initcall() instead of module_init(), such that the previous
> initialization ordering is restored. I didn't restore the late_initcall()
> since start_stop_khugepaged() already sets min_free_kbytes via
> set_recommended_min_free_kbytes().
>
> This was noticed when we had a number of page allocation failures when
> moving a workload to a kernel with this new initialization ordering. On an
> 8GB system this restores min_free_kbytes back to 67584 from 11365 when
> CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
> CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
>
> Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
> Signed-off-by: Jason Baron <jbaron@akamai.com>
Looks good to me:
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
@ 2016-04-13 10:36 ` Kirill A. Shutemov
0 siblings, 0 replies; 8+ messages in thread
From: Kirill A. Shutemov @ 2016-04-13 10:36 UTC (permalink / raw)
To: Jason Baron
Cc: akpm, kirill.shutemov, rientjes, aarcange, mgorman, mhocko,
hannes, vbabka, linux-mm, linux-kernel
On Tue, Apr 12, 2016 at 03:54:37PM -0400, Jason Baron wrote:
> Khugepaged attempts to raise min_free_kbytes if its set too low. However,
> on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
> then the mm 'core' over-rides min_free_kbytes after from
> init_per_zone_wmark_min(), via a module_init() call.
>
> Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
> it occurred after the core initialization), however this was removed when
> the initialization of min_free_kbytes was integrated into the starting of
> the khugepaged thread.
>
> The fix here is simply to invoke the core initialization using a
> core_initcall() instead of module_init(), such that the previous
> initialization ordering is restored. I didn't restore the late_initcall()
> since start_stop_khugepaged() already sets min_free_kbytes via
> set_recommended_min_free_kbytes().
>
> This was noticed when we had a number of page allocation failures when
> moving a workload to a kernel with this new initialization ordering. On an
> 8GB system this restores min_free_kbytes back to 67584 from 11365 when
> CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
> CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
>
> Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
> Signed-off-by: Jason Baron <jbaron@akamai.com>
Looks good to me:
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
2016-04-12 19:54 ` Jason Baron
@ 2016-04-14 20:08 ` David Rientjes
-1 siblings, 0 replies; 8+ messages in thread
From: David Rientjes @ 2016-04-14 20:08 UTC (permalink / raw)
To: Jason Baron
Cc: akpm, kirill.shutemov, aarcange, mgorman, mhocko, hannes, vbabka,
linux-mm, linux-kernel
On Tue, 12 Apr 2016, Jason Baron wrote:
> Khugepaged attempts to raise min_free_kbytes if its set too low. However,
> on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
> then the mm 'core' over-rides min_free_kbytes after from
> init_per_zone_wmark_min(), via a module_init() call.
>
> Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
> it occurred after the core initialization), however this was removed when
> the initialization of min_free_kbytes was integrated into the starting of
> the khugepaged thread.
>
> The fix here is simply to invoke the core initialization using a
> core_initcall() instead of module_init(), such that the previous
> initialization ordering is restored. I didn't restore the late_initcall()
> since start_stop_khugepaged() already sets min_free_kbytes via
> set_recommended_min_free_kbytes().
>
> This was noticed when we had a number of page allocation failures when
> moving a workload to a kernel with this new initialization ordering. On an
> 8GB system this restores min_free_kbytes back to 67584 from 11365 when
> CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
> CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
>
> Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
> Signed-off-by: Jason Baron <jbaron@akamai.com>
Acked-by: David Rientjes <rientjes@google.com>
I assume it could also be fixed by not setting min_free_kbytes lower in
init_per_zone_wmark_min(), but if the ordering is correct this is less
code.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization
@ 2016-04-14 20:08 ` David Rientjes
0 siblings, 0 replies; 8+ messages in thread
From: David Rientjes @ 2016-04-14 20:08 UTC (permalink / raw)
To: Jason Baron
Cc: akpm, kirill.shutemov, aarcange, mgorman, mhocko, hannes, vbabka,
linux-mm, linux-kernel
On Tue, 12 Apr 2016, Jason Baron wrote:
> Khugepaged attempts to raise min_free_kbytes if its set too low. However,
> on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and
> then the mm 'core' over-rides min_free_kbytes after from
> init_per_zone_wmark_min(), via a module_init() call.
>
> Khugepaged used to use a late_initcall() to set min_free_kbytes (such that
> it occurred after the core initialization), however this was removed when
> the initialization of min_free_kbytes was integrated into the starting of
> the khugepaged thread.
>
> The fix here is simply to invoke the core initialization using a
> core_initcall() instead of module_init(), such that the previous
> initialization ordering is restored. I didn't restore the late_initcall()
> since start_stop_khugepaged() already sets min_free_kbytes via
> set_recommended_min_free_kbytes().
>
> This was noticed when we had a number of page allocation failures when
> moving a workload to a kernel with this new initialization ordering. On an
> 8GB system this restores min_free_kbytes back to 67584 from 11365 when
> CONFIG_TRANSPARENT_HUGEPAGE=y is set and either
> CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or
> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
>
> Fixes: 79553da293d3 ("thp: cleanup khugepaged startup")
> Signed-off-by: Jason Baron <jbaron@akamai.com>
Acked-by: David Rientjes <rientjes@google.com>
I assume it could also be fixed by not setting min_free_kbytes lower in
init_per_zone_wmark_min(), but if the ordering is correct this is less
code.
--
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^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2016-04-14 20:08 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2016-04-12 19:54 [PATCH 0/1] mm: setting of min_free_kbytes Jason Baron
2016-04-12 19:54 ` Jason Baron
2016-04-12 19:54 ` [PATCH 1/1] mm: update min_free_kbytes from khugepaged after core initialization Jason Baron
2016-04-12 19:54 ` Jason Baron
2016-04-13 10:36 ` Kirill A. Shutemov
2016-04-13 10:36 ` Kirill A. Shutemov
2016-04-14 20:08 ` David Rientjes
2016-04-14 20:08 ` David Rientjes
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