The patch titled
Subject: mm: document highmem_is_dirtyable sysctl
has been removed from the -mm tree. Its filename was
mm-document-highmem_is_dirtyable-sysctl.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm: document highmem_is_dirtyable sysctl
It seems that there are still people using 32b kernels which a lot of
memory and the IO tend to suck a lot for them by default. Mostly because
writers are throttled too when the lowmem is used. We have
highmem_is_dirtyable to work around that issue but it seems we never
bothered to document it. Let's do it now, finally.
Link: http://lkml.kernel.org/r/20170626093200.18958-1-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Alkis Georgopoulos <alkisg@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/sysctl/vm.txt | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff -puN Documentation/sysctl/vm.txt~mm-document-highmem_is_dirtyable-sysctl Documentation/sysctl/vm.txt
--- a/Documentation/sysctl/vm.txt~mm-document-highmem_is_dirtyable-sysctl
+++ a/Documentation/sysctl/vm.txt
@@ -240,6 +240,26 @@ fragmentation index is <= extfrag_thresh
==============================================================
+highmem_is_dirtyable
+
+Available only for systems with CONFIG_HIGHMEM enabled (32b systems).
+
+This parameter controls whether the high memory is considered for dirty
+writers throttling. This is not the case by default which means that
+only the amount of memory directly visible/usable by the kernel can
+be dirtied. As a result, on systems with a large amount of memory and
+lowmem basically depleted writers might be throttled too early and
+streaming writes can get very slow.
+
+Changing the value to non zero would allow more memory to be dirtied
+and thus allow writers to write more data which can be flushed to the
+storage more effectively. Note this also comes with a risk of pre-mature
+OOM killer because some writers (e.g. direct block device writes) can
+only use the low memory and they can fill it up with dirty data without
+any throttling.
+
+==============================================================
+
hugepages_treat_as_movable
This parameter controls whether we can allocate hugepages from ZONE_MOVABLE
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
netfilter-use-kvmalloc-xt_alloc_table_info.patch
mips-do-not-use-__gfp_repeat-for-order-0-request.patch
mm-tree-wide-replace-__gfp_repeat-by-__gfp_retry_mayfail-with-more-useful-semantic.patch
mm-tree-wide-replace-__gfp_repeat-by-__gfp_retry_mayfail-with-more-useful-semantic-fix-2.patch
xfs-map-km_mayfail-to-__gfp_retry_mayfail.patch
mm-kvmalloc-support-__gfp_retry_mayfail-for-all-sizes.patch
drm-i915-use-__gfp_retry_mayfail.patch
mm-migration-do-not-trigger-oom-killer-when-migrating-memory.patch
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