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Feature #12870

closed

bhyve should allocate guest memory lazily

Added by Patrick Mooney about 2 years ago. Updated 10 months ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
bhyve
Start date:
Due date:
% Done:

0%

Estimated time:
Difficulty:
Medium
Tags:
bhyve
Gerrit CR:

Description

For the initial porting effort of bhyve, the way we shimmed allocation for guest physical memory regions is with equally sized (read: gigantic) kmem_alloc() calls. For small guests on systems without memory pressure, it's simple and works OK, but the model starts to suffer with larger guests and in the face of memory pressure.

In particular, it means allocating and zeroing literally all of guest memory at the time of VM creation, which can be very expensive. Without exposing ourselves to the challenges of swap-able guest memory (and the performance dangers of overcommit there), it would be nice if instances could "demand-page" their guest-physical allocations over a longer period, while the VM is up and running.

Actions #1

Updated by Patrick Mooney 10 months ago

  • Status changed from In Progress to Closed
  • Assignee deleted (Patrick Mooney)

With the integration of #13833, the situation for guest memory allocation changed significantly. It may be that lazy allocation is desired or needed in the future. This can be revisited then.

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