[PATCH v1] docs: sysctl: timer_migration is for hrtimer only

[Costa Shulyupin <costa.shul@redhat.com>]

Since commit b2cf7507e1864 ("timers: Always queue timers on the local
CPU") __mod_timer() no longer depends on timers_migration_enabled.  Only
high-resolution timer migration from isolated to housekeeping CPUs
depends on it.

Update and clarify the documentation accordingly.

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
---
 Documentation/admin-guide/sysctl/kernel.rst | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index b6328cd0f43e..fb38d654846d 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1609,8 +1609,10 @@ If a value outside of this range is written to ``threads-max`` an
 timer_migration
 ===============
 
-When set to a non-zero value, attempt to migrate timers away from idle cpus to
-allow them to remain in low power states longer.
+When set to a non-zero value, attempt to migrate high-resolution timers from
+nohz isolated (nohz_full) to housekeeping CPUs.
+See Documentation/admin-guide/cpu-isolation.rst
+and Documentation/admin-guide/kernel-parameters.rst.
 
 Default is set (1).
 
-- 
2.55.0