docs: virt: guest-halt-polling.txt convert to ReST

Due to some merge conflict, this file ended being alone under
Documentation/virtual.

The file itself is almost at ReST format. Just minor
adjustments are needed:

- Adjust title markup;
- Adjust a list identation;
- add a literal block markup;
- Add some blank lines.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virt/guest-halt-polling.rst b/Documentation/virt/guest-halt-polling.rst
new file mode 100644 (file)
index 0000000..b4e7479
--- /dev/null
+++ b/Documentation/virt/guest-halt-polling.rst
@@ -0,0 +1,84 @@
+==================
+Guest halt polling
+==================
+
+The cpuidle_haltpoll driver, with the haltpoll governor, allows
+the guest vcpus to poll for a specified amount of time before
+halting.
+
+This provides the following benefits to host side polling:
+
+       1) The POLL flag is set while polling is performed, which allows
+          a remote vCPU to avoid sending an IPI (and the associated
+          cost of handling the IPI) when performing a wakeup.
+
+       2) The VM-exit cost can be avoided.
+
+The downside of guest side polling is that polling is performed
+even with other runnable tasks in the host.
+
+The basic logic as follows: A global value, guest_halt_poll_ns,
+is configured by the user, indicating the maximum amount of
+time polling is allowed. This value is fixed.
+
+Each vcpu has an adjustable guest_halt_poll_ns
+("per-cpu guest_halt_poll_ns"), which is adjusted by the algorithm
+in response to events (explained below).
+
+Module Parameters
+=================
+
+The haltpoll governor has 5 tunable module parameters:
+
+1) guest_halt_poll_ns:
+
+Maximum amount of time, in nanoseconds, that polling is
+performed before halting.
+
+Default: 200000
+
+2) guest_halt_poll_shrink:
+
+Division factor used to shrink per-cpu guest_halt_poll_ns when
+wakeup event occurs after the global guest_halt_poll_ns.
+
+Default: 2
+
+3) guest_halt_poll_grow:
+
+Multiplication factor used to grow per-cpu guest_halt_poll_ns
+when event occurs after per-cpu guest_halt_poll_ns
+but before global guest_halt_poll_ns.
+
+Default: 2
+
+4) guest_halt_poll_grow_start:
+
+The per-cpu guest_halt_poll_ns eventually reaches zero
+in case of an idle system. This value sets the initial
+per-cpu guest_halt_poll_ns when growing. This can
+be increased from 10000, to avoid misses during the initial
+growth stage:
+
+10k, 20k, 40k, ... (example assumes guest_halt_poll_grow=2).
+
+Default: 50000
+
+5) guest_halt_poll_allow_shrink:
+
+Bool parameter which allows shrinking. Set to N
+to avoid it (per-cpu guest_halt_poll_ns will remain
+high once achieves global guest_halt_poll_ns value).
+
+Default: Y
+
+The module parameters can be set from the debugfs files in::
+
+       /sys/module/haltpoll/parameters/
+
+Further Notes
+=============
+
+- Care should be taken when setting the guest_halt_poll_ns parameter as a
+  large value has the potential to drive the cpu usage to 100% on a machine
+  which would be almost entirely idle otherwise.

diff --git a/Documentation/virt/index.rst b/Documentation/virt/index.rst
index 0a8f7fda64ada3e5cd18f7fc496d49dbf425c516..de1ab81df95802b2a8a5b34e6b05ef98d422f6a0 100644 (file)
--- a/Documentation/virt/index.rst
+++ b/Documentation/virt/index.rst
@@ -10,6 +10,7 @@ Linux Virtualization Support
    kvm/index
    uml/user_mode_linux
    paravirt_ops
+   guest-halt-polling
 
 .. only:: html and subproject
 

diff --git a/Documentation/virtual/guest-halt-polling.txt b/Documentation/virtual/guest-halt-polling.txt
deleted file mode 100644 (file)
index b3a2a29..0000000
--- a/Documentation/virtual/guest-halt-polling.txt
+++ /dev/null
@@ -1,78 +0,0 @@
-Guest halt polling
-==================
-
-The cpuidle_haltpoll driver, with the haltpoll governor, allows
-the guest vcpus to poll for a specified amount of time before
-halting.
-This provides the following benefits to host side polling:
-
-       1) The POLL flag is set while polling is performed, which allows
-          a remote vCPU to avoid sending an IPI (and the associated
-          cost of handling the IPI) when performing a wakeup.
-
-       2) The VM-exit cost can be avoided.
-
-The downside of guest side polling is that polling is performed
-even with other runnable tasks in the host.
-
-The basic logic as follows: A global value, guest_halt_poll_ns,
-is configured by the user, indicating the maximum amount of
-time polling is allowed. This value is fixed.
-
-Each vcpu has an adjustable guest_halt_poll_ns
-("per-cpu guest_halt_poll_ns"), which is adjusted by the algorithm
-in response to events (explained below).
-
-Module Parameters
-=================
-
-The haltpoll governor has 5 tunable module parameters:
-
-1) guest_halt_poll_ns:
-Maximum amount of time, in nanoseconds, that polling is
-performed before halting.
-
-Default: 200000
-
-2) guest_halt_poll_shrink:
-Division factor used to shrink per-cpu guest_halt_poll_ns when
-wakeup event occurs after the global guest_halt_poll_ns.
-
-Default: 2
-
-3) guest_halt_poll_grow:
-Multiplication factor used to grow per-cpu guest_halt_poll_ns
-when event occurs after per-cpu guest_halt_poll_ns
-but before global guest_halt_poll_ns.
-
-Default: 2
-
-4) guest_halt_poll_grow_start:
-The per-cpu guest_halt_poll_ns eventually reaches zero
-in case of an idle system. This value sets the initial
-per-cpu guest_halt_poll_ns when growing. This can
-be increased from 10000, to avoid misses during the initial
-growth stage:
-
-10k, 20k, 40k, ... (example assumes guest_halt_poll_grow=2).
-
-Default: 50000
-
-5) guest_halt_poll_allow_shrink:
-
-Bool parameter which allows shrinking. Set to N
-to avoid it (per-cpu guest_halt_poll_ns will remain
-high once achieves global guest_halt_poll_ns value).
-
-Default: Y
-
-The module parameters can be set from the debugfs files in:
-
-       /sys/module/haltpoll/parameters/
-
-Further Notes
-=============
-
-- Care should be taken when setting the guest_halt_poll_ns parameter as a
-large value has the potential to drive the cpu usage to 100% on a machine which
-would be almost entirely idle otherwise.