Examples: Resizing DRAM Tier for KVM

Following are some examples of resizing DRAM tier and switching HugePages on and off. You can follow the examples using a VM on your own system by typing the commands shown.

Enable the DRAM Tier

The VM is started using the following application configuration file:

DpmeSocketName: /tmp/dpme_daemon.0
MmapCapture: true
MallocCapture: true
LogName: /var/log/memverge/kvm.log
CommPort: 5678
EnableSnapshot: false
DramTierGB: 0
HugePageDram: false

The DRAM tier is disabled, as specified in the file:

# mvmcli show-usage -v -p 47946
This instance is using 36.73 MiB DRAM, 1594.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
DRAM Tier is not enabled.
#

Resize the DRAM tier to 2 GB with HugePages:

# mvmcli dram resize -s 2048 -p 47946 -g true
DRAM tier is resized to 2048 MB using huge page on process 47946
# mvmcli show-usage -v -p 47946
This instance is using 36.73 MiB DRAM, 1660.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 2048.00
Allocated DRAM size (MiB): 256.00
Mapped DRAM size (MiB) : 0.00
Use HugePages: Yes
#

Disable the DRAM Tier

The VM starts with DRAM tier set to 4 GB and HugePages on:

# mvmcli show-usage -v -p 47946
This instance is using 1628.68 MiB DRAM, 0.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 4096.00
Allocated DRAM size (MiB): 1792.00
Mapped DRAM size (MiB) : 1592.00
Use HugePages: Yes
#

Disable the DRAM tier:

# mvmcli dram resize -s 0 -p 47946
DRAM tier is disabled on process 47946
# mvmcli show-usage -v -p 47946
This instance is using 36.73 MiB DRAM, 1594.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
DRAM Tier is not enabled.
#

Expand the DRAM Tier

The VM starts with DRAM set to 4 GB with HugePages on. All DRAM tier is in use (mapped DRAM size is 4096):

# mvmcli show-usage -v -p 41076
This instance is using 4133.02 MiB DRAM, 492.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 4096.00
Allocated DRAM size (MiB): 4096.00
Mapped DRAM size (MiB) : 4096.00 
Use HugePages: Yes
#

Resize the DRAM tier to 8 GB:

# mvmcli dram resize -s 8192 -p 41076
DRAM tier is resized to 8192 MB using huge page on process 41076
# mvmcli show-usage -v -p 41076
This instance is using 8229.02 MiB DRAM, 1408.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 8192.00
Allocated DRAM size (MiB): 8192.00
Mapped DRAM size (MiB) : 8192.00
Use HugePages: Yes
#

Shrink the DRAM Tier

The VM starts with DRAM set to 8GB with HugePages on:

# mvmcli show-usage -v -p 49503
This instance is using 7592.94 MiB DRAM, 0.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 8192.00    DRAM tier is 8G
Allocated DRAM size (MiB): 7680.00
Mapped DRAM size (MiB) : 7554.00
Use HugePages: Yes
#

Resize the DRAM tier to 4 GB:

# mvmcli dram resize -s 4096 -p 49503
DRAM tier is resized to 4096 MB using huge page on process 49503
# mvmcli show-usage -v -p 49503
This instance is using 4136.96 MiB DRAM, 3466.00 MiB PMEM for current execution and 0.00 MiB PMEM for snapshots
Configured DRAM iter size (MiB): 4096.00   DRAM tier is to 4G, some memory goes to PMEM
Allocated DRAM size (MiB): 4096.00
Mapped DRAM size (MiB) : 4096.00
Use HugePages: Yes
#

The DRAM tier is reduced to 4 GB. HugePages are still in use.