How to determine the memory allocated to the VMware Balloon driver [vmw_balloon] (shipped with RHEL) from vmcore?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • VMware Virtual Platform
  • VMware balloon module [vmw_balloon] or [vmware_balloon]

Issue

  • How to determine the memory allocated to the VMware Balloon driver [vmw_balloon] (shipped with RHEL) from vmcore?

Resolution

  • The memory allocated to VMware Balloon driver (shipped with RHEL) can be determined from the "struct vmballoon->size" and "struct vmballoon->target" variables.

  • The "struct vmballoon->size" variable contains the amount of memory consumed by VMware Balloon driver [vmw_balloon] in pages.

    crash> struct vmballoon.size -ox
struct vmballoon {
   [0x54] unsigned int size;
}

  • The "struct vmballoon->target" variable contains the amount of memory VMware Balloon driver [vmw_balloon] is going to consume in pages.

    crash> struct vmballoon.target -ox
struct vmballoon {
   [0x58] unsigned int target;
}

Steps to determine the memory allocated to VMware Balloon driver [vmw_balloon] from vmcore:

  1. Load symbolic and debugging data from the object file of [vmw_balloon] module (i.e., vmw_balloon.ko.debug) in crash. Note: For RHEL 6 use the VMware Balloon driver name [vmware_balloon] (i.e., mod -s vmware_balloon).

    crash> mod -s vmw_balloon

Eg:
crash> mod -s vmw_balloon
     MODULE       NAME                BASE           SIZE  OBJECT FILE
ffffffffc05c0340  vmw_balloon   ffffffffc05bc000    24576  /usr/lib/debug/lib/modules/4.18.0-425.19.2.el8_7.x86_64/kernel/drivers/misc/vmw_balloon.ko.debug

  2. Determine the value of struct vmballoon->size variable using the address of symbol balloon.

    crash> sym balloon
ffffffffc05c06c0 (b) balloon [vmw_balloon]

crash> pd balloon.size
$1 = 2721049 (pages)

OR

crash> struct vmballoon.size balloon
  size = 2721049 (pages)

crash> !bc -q
scale=2
2721049*4/2^20
10.37 (GiB)
    • In the above example, the amount of memory consumed by VMware Balloon driver [vmw_balloon] is 10.37 GiB (2721049 pages).

  3. Determine the value of struct vmballoon->target variable using the address of symbol balloon.

    crash> sym balloon
ffffffffc05c06c0 (b) balloon [vmw_balloon]

crash> pd balloon.target
$2 = 3177311 (pages)

OR

crash> struct vmballoon.target balloon
  target = 3177311 (pages)

crash> !bc -q
scale=2
3177311*4/2^20
12.12 (GiB)
    • In the above example, the amount of memory needed by VMware Balloon driver [vmw_balloon] is 12.12 GiB (3177311 pages).

Note:

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