Fix the +RTS -V0 option introduced recently; it didn't work at all, now it does.

[ghc-hetmet.git] / docs / users_guide / runtime_control.xml

diff --git a/docs/users_guide/runtime_control.xml b/docs/users_guide/runtime_control.xml
index e89f340..95365ba 100644 (file)
--- a/docs/users_guide/runtime_control.xml
+++ b/docs/users_guide/runtime_control.xml
@@ -108,6 +108,14 @@
          the <option>-C</option> or <option>-i</option> options.
          However, setting <option>-V</option> is required in order to
          increase the resolution of the time profiler.</para>
+
+         <para>Using a value of zero disables the RTS clock
+         completetly, and has the effect of disabling timers that
+         depend on it: the context switch timer and the heap profiling
+         timer.  Context switches will still happen, but
+         deterministically and at a rate much faster than normal.
+         Disabling the interval timer is useful for debugging, because
+         it eliminates a source of non-determinism at runtime.</para>
        </listitem>
      </varlistentry>