From 28f25b0d334e24808bbccfeb4ab7e17a26fcb6dd Mon Sep 17 00:00:00 2001 From: Olaf Hering Date: Thu, 30 Aug 2012 17:57:31 +0100 Subject: docs: update xenpaging.txt Signed-off-by: Olaf Hering Committed-by: Keir Fraser --- docs/misc/xenpaging.txt | 43 ++++++++++++++++++++----------------------- 1 file changed, 20 insertions(+), 23 deletions(-) (limited to 'docs/misc') diff --git a/docs/misc/xenpaging.txt b/docs/misc/xenpaging.txt index e26c57ded0..742523e145 100644 --- a/docs/misc/xenpaging.txt +++ b/docs/misc/xenpaging.txt @@ -12,37 +12,34 @@ access the paged-out memory, the page is read from disk and placed into memory. This allows the sum of all running guests to use more memory than physically available on the host. -Usage: - -Once the guest is running, run xenpaging with the guest_id and the -number of pages to page-out: - - chdir /var/lib/xen/xenpaging - xenpaging +Requirements: -To obtain the guest_id, run 'xm list'. -xenpaging will write the pagefile to the current directory. -Example with 128MB pagefile on guest 1: +xenpaging relies on Intel EPT or AMD RVI, other hardware is not +supported. Only HVM guests are supported. The dom0 kernel needs +paging-aware backend drivers to handle paged granttable entries. +Currently only dom0 kernels based on classic Xen Linux support this +functionality. - xenpaging 1 32768 +Usage: -Caution: stopping xenpaging manually will cause the guest to stall or -crash because the paged-out memory is not written back into the guest! +Up to now xenpaging is not integrated into libxl/xend, so it has to be +started manually for each guest. -After a reboot of a guest, its guest_id changes, the current xenpaging -binary has no target anymore. To automate restarting of xenpaging after -guest reboot, specify the number if pages in the guest configuration -file /etc/xen/vm/: +Once the guest is running, run xenpaging with the guest_id and the path +to the pagefile: + + /usr/lib/xen/bin/xenpaging -f /path/to/page_file -d dom_id & -xenpaging=32768 +Once xenpaging runs it needs a memory target, which is the memory +footprint of the guest. This value (in KiB) must be written manually to +xenstore. The following example sets the target to 512MB: -Redo the guest with 'xm create /etc/xen/vm/' to activate the -changes. + xenstore-write /local/domain//memory/target-tot_pages $((1024*512)) +Now xenpaging tries to page-out as many pages to keep the overall memory +footprint of the guest at 512MB. Todo: -- implement stopping of xenpaging -- implement/test live migration - +- integrate xenpaging into libxl # vim: tw=72 -- cgit v1.2.3