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-rw-r--r--Documentation/admin-guide/mm/zswap.rst10
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
index 62fc244ec702..b42132969e31 100644
--- a/Documentation/admin-guide/mm/zswap.rst
+++ b/Documentation/admin-guide/mm/zswap.rst
@@ -153,6 +153,16 @@ attribute, e. g.::
Setting this parameter to 100 will disable the hysteresis.
+Some users cannot tolerate the swapping that comes with zswap store failures
+and zswap writebacks. Swapping can be disabled entirely (without disabling
+zswap itself) on a cgroup-basis as follows:
+
+ echo 0 > /sys/fs/cgroup/<cgroup-name>/memory.zswap.writeback
+
+Note that if the store failures are recurring (for e.g if the pages are
+incompressible), users can observe reclaim inefficiency after disabling
+writeback (because the same pages might be rejected again and again).
+
When there is a sizable amount of cold memory residing in the zswap pool, it
can be advantageous to proactively write these cold pages to swap and reclaim
the memory for other use cases. By default, the zswap shrinker is disabled.