Commit 54319982 authored by Mike Rapoport's avatar Mike Rapoport Committed by Jonathan Corbet
Browse files

docs/vm: swap_numa.txt: convert to ReST format 



Signed-off-by: default avatarMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent d18edf52

Documentation/vm/swap_numa.txt

+33 −22
Original line number Diff line number Diff line 
.. _swap_numa:



===========================================

Automatically bind swap device to numa node

-------------------------------------------

===========================================



If the system has more than one swap device and swap device has the node

information, we can make use of this information to decide which swap
@@ -7,13 +10,14 @@ device to use in get_swap_pages() to get better performance. 




How to use this feature

-----------------------

=======================



Swap device has priority and that decides the order of it to be used. To make

use of automatically binding, there is no need to manipulate priority settings

for swap devices. e.g. on a 2 node machine, assume 2 swap devices swapA and

swapB, with swapA attached to node 0 and swapB attached to node 1, are going

to be swapped on. Simply swapping them on by doing:

to be swapped on. Simply swapping them on by doing::



	# swapon /dev/swapA

	# swapon /dev/swapB
@@ -24,7 +28,8 @@ that the order of them being swapped on doesn't matter. 
A more complex example on a 4 node machine. Assume 6 swap devices are going to

be swapped on: swapA and swapB are attached to node 0, swapC is attached to

node 1, swapD and swapE are attached to node 2 and swapF is attached to node3.

The way to swap them on is the same as above:

The way to swap them on is the same as above::



	# swapon /dev/swapA

	# swapon /dev/swapB

	# swapon /dev/swapC
@@ -32,24 +37,30 @@ The way to swap them on is the same as above: 
	# swapon /dev/swapE

	# swapon /dev/swapF



Then node 0 will use them in the order of:

Then node 0 will use them in the order of::



	swapA/swapB -> swapC -> swapD -> swapE -> swapF



swapA and swapB will be used in a round robin mode before any other swap device.



node 1 will use them in the order of:

node 1 will use them in the order of::



	swapC -> swapA -> swapB -> swapD -> swapE -> swapF



node 2 will use them in the order of:

node 2 will use them in the order of::



	swapD/swapE -> swapA -> swapB -> swapC -> swapF



Similaly, swapD and swapE will be used in a round robin mode before any

other swap devices.



node 3 will use them in the order of:

node 3 will use them in the order of::



	swapF -> swapA -> swapB -> swapC -> swapD -> swapE





Implementation details

----------------------

======================



The current code uses a priority based list, swap_avail_list, to decide

which swap device to use and if multiple swap devices share the same