Advanced Memory Attributes
You can use the advanced memory attributes to customize memory resource usage.
Table B-2. Advanced Memory Attributes
Attribute Description Default
Mem.CtlMaxPercent Limits the maximum amount of memory reclaimed from any virtual
machine using vmmemctl, based on a percentage of its configured
memory size. Specify 0 to disable reclamation using vmmemctl for
all virtual machines.
65
Mem.ShareScanTime Specifies the time, in minutes, within which an entire virtual
machine is scanned for page sharing opportunities. Defaults to 60
minutes.
60
Mem.ShareScanGHz Specifies the maximum amount of memory pages to scan (per
second) for page sharing opportunities for each GHz of available
host CPU resource.
Defaults to 4 MB/sec per 1GHz.
4
Mem.IdleTax Specifies the idle memory tax rate, as a percentage. This tax
effectively charges virtual machines more for idle memory than for
memory they are actively using. A tax rate of 0 percent defines an
allocation policy that ignores working sets and allocates memory
strictly based on shares. A high tax rate results in an allocation policy
that allows idle memory to be reallocated away from virtual
machines that are unproductively hoarding it.
75
Mem.SamplePeriod Specifies the periodic time interval, measured in seconds of the
virtual machine’s execution time, over which memory activity is
monitored to estimate working set sizes.
60
Mem.BalancePeriod Specifies the periodic time interval, in seconds, for automatic
memory reallocations. Significant changes in the amount of free
memory also trigger reallocations.
15
Mem.AllocGuestLargePage Set this option to 1 to enable backing of guest large pages with host
large pages. Reduces TLB misses and improves performance in
server workloads that use guest large pages. 0=disable.
1
Mem.AllocUsePSharePool
and
Mem.AllocUseGuestPool
Set these options to 1 to reduce memory fragmentation. If host
memory is fragmented, the availability of host large pages is
reduced. These options improve the probability of backing guest
large pages with host large pages. 0 = disable.
1
LPage.LPageDefragEnable Set this option to 1 to enable large page defragmentation. 0 = disable. 1
LPage.LPageDefragRateVM Maximum number of large page defragmentation attempts per
second per virtual machine. Accepted values range from 1 to 1024.
2
LPage.LPageDefragRateTotal Maximum number of large page defragmentation attempts per
second. Accepted values range from 1 to 10240.
8
LPage.LPageAlwaysTryForNPT Set this option to 1 to enable always try to allocate large pages for
nested page tables (NPTs). 0= disable.
If you enable this option, all guest memory is backed with large
pages in machines that use nested page tables (for example, AMD
Barcelona). If NPT is not available, only some portion of guest
memory is backed with large pages.
1
vSphere Resource Management Guide
98 VMware, Inc.
