197ecb3802
Scrubbing pages on initial balloon down can take some time, especially in nested virtualization case (nested EPT is slow). When HVM/PVH guest is started with memory= significantly lower than maxmem=, all the extra pages will be scrubbed before returning to Xen. But since most of them weren't used at all at that point, Xen needs to populate them first (from populate-on-demand pool). In nested virt case (Xen inside KVM) this slows down the guest boot by 15-30s with just 1.5GB needed to be returned to Xen. Add runtime parameter to enable/disable it, to allow initially disabling scrubbing, then enable it back during boot (for example in initramfs). Such usage relies on assumption that a) most pages ballooned out during initial boot weren't used at all, and b) even if they were, very few secrets are in the guest at that time (before any serious userspace kicks in). Convert CONFIG_XEN_SCRUB_PAGES to CONFIG_XEN_SCRUB_PAGES_DEFAULT (also enabled by default), controlling default value for the new runtime switch. Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2.9 KiB
What: /sys/devices/system/xen_memory/xen_memory0/max_retry_count Date: May 2011 KernelVersion: 2.6.39 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: The maximum number of times the balloon driver will attempt to increase the balloon before giving up. See also 'retry_count' below. A value of zero means retry forever and is the default one.
What: /sys/devices/system/xen_memory/xen_memory0/max_schedule_delay Date: May 2011 KernelVersion: 2.6.39 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: The limit that 'schedule_delay' (see below) will be increased to. The default value is 32 seconds.
What: /sys/devices/system/xen_memory/xen_memory0/retry_count Date: May 2011 KernelVersion: 2.6.39 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: The current number of times that the balloon driver has attempted to increase the size of the balloon. The default value is one. With max_retry_count being zero (unlimited), this means that the driver will attempt to retry with a 'schedule_delay' delay.
What: /sys/devices/system/xen_memory/xen_memory0/schedule_delay Date: May 2011 KernelVersion: 2.6.39 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: The time (in seconds) to wait between attempts to increase the balloon. Each time the balloon cannot be increased, 'schedule_delay' is increased (until 'max_schedule_delay' is reached at which point it will use the max value).
What: /sys/devices/system/xen_memory/xen_memory0/target Date: April 2008 KernelVersion: 2.6.26 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: The target number of pages to adjust this domain's memory reservation to.
What: /sys/devices/system/xen_memory/xen_memory0/target_kb Date: April 2008 KernelVersion: 2.6.26 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: As target above, except the value is in KiB.
What: /sys/devices/system/xen_memory/xen_memory0/info/current_kb Date: April 2008 KernelVersion: 2.6.26 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: Current size (in KiB) of this domain's memory reservation.
What: /sys/devices/system/xen_memory/xen_memory0/info/high_kb Date: April 2008 KernelVersion: 2.6.26 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: Amount (in KiB) of high memory in the balloon.
What: /sys/devices/system/xen_memory/xen_memory0/info/low_kb Date: April 2008 KernelVersion: 2.6.26 Contact: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Description: Amount (in KiB) of low (or normal) memory in the balloon.
What: /sys/devices/system/xen_memory/xen_memory0/scrub_pages Date: September 2018 KernelVersion: 4.20 Contact: xen-devel@lists.xenproject.org Description: Control scrubbing pages before returning them to Xen for others domains use. Can be set with xen_scrub_pages cmdline parameter. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.