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authorH.J. Lu <hjl.tools@gmail.com>2020-06-01 14:11:32 -0700
committerH.J. Lu <hjl.tools@gmail.com>2020-09-29 09:03:47 -0700
commitdfb8e514cf4d770a9ce4e7858a351b9a2893614d (patch)
treec6d59af2a286ae6a241c23ce26be7d97223741d3 /manual
parentc6702789344043fa998923c8f32ed0bdb2edfa9c (diff)
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Set tunable value as well as min/max values
Some tunable values and their minimum/maximum values must be determinted at run-time. Add TUNABLE_SET_WITH_BOUNDS and TUNABLE_SET_WITH_BOUNDS_FULL to update tunable value together with minimum and maximum values. __tunable_set_val is updated to set tunable value as well as min/max values.
Diffstat (limited to 'manual')
-rw-r--r--manual/README.tunables24
1 files changed, 22 insertions, 2 deletions
diff --git a/manual/README.tunables b/manual/README.tunables
index f87a31a65e0..fff6c2a87e9 100644
--- a/manual/README.tunables
+++ b/manual/README.tunables
@@ -67,7 +67,7 @@ The list of allowed attributes are:
non-AT_SECURE subprocesses.
NONE: Read all the time.
-2. Use TUNABLE_GET/TUNABLE_SET to get and set tunables.
+2. Use TUNABLE_GET/TUNABLE_SET/TUNABLE_SET_WITH_BOUNDS to get and set tunables.
3. OPTIONAL: If tunables in a namespace are being used multiple times within a
specific module, set the TUNABLE_NAMESPACE macro to reduce the amount of
@@ -112,9 +112,29 @@ form of the macros as follows:
where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
remaining arguments are the same as the short form macros.
+The minimum and maximum values can updated together with the tunable value
+using:
+
+ TUNABLE_SET_WITH_BOUNDS (check, int32_t, val, min, max)
+
+where 'check' is the tunable name, 'int32_t' is the C type of the tunable,
+'val' is a value of same type, 'min' and 'max' are the minimum and maximum
+values of the tunable.
+
+To set the minimum and maximum values of tunables in a different namespace
+from that module, use the full form of the macros as follows:
+
+ val = TUNABLE_GET_FULL (glibc, cpu, hwcap_mask, uint64_t, NULL)
+
+ TUNABLE_SET_WITH_BOUNDS_FULL (glibc, cpu, hwcap_mask, uint64_t, val, min, max)
+
+where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
+remaining arguments are the same as the short form macros.
+
When TUNABLE_NAMESPACE is not defined in a module, TUNABLE_GET is equivalent to
TUNABLE_GET_FULL, so you will need to provide full namespace information for
-both macros. Likewise for TUNABLE_SET and TUNABLE_SET_FULL.
+both macros. Likewise for TUNABLE_SET, TUNABLE_SET_FULL,
+TUNABLE_SET_WITH_BOUNDS and TUNABLE_SET_WITH_BOUNDS_FULL.
** IMPORTANT NOTE **