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[Xen-devel] xl only waits 33 seconds for ballooning to complete

  • To: xen-devel@xxxxxxxxxxxxx
  • From: Mike Latimer <mlatimer@xxxxxxxx>
  • Date: Tue, 06 Jan 2015 14:17:23 -0700
  • Delivery-date: Tue, 06 Jan 2015 21:18:10 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>


In a previous post (1), I mentioned issues seen while ballooning a large 
amount of memory. In the current code, the ballooning process only has 33 
seconds to complete, or the xl operation (i.e. domain create) will fail. When 
a lot of ballooning is required, or the host is very slow to balloon memory, 
this delay is not sufficient.

The code involved is tools/libxl/xl_cmdimpl.c:freemem. This function retries 3 
times, and each retry includes a 10 second delay in libxl_wait_for_free_memory 
and a 1 second delay in libxl_wait_for_memory_target.

Is there a better approach, which would account for ballooning operations that 
take a much longer time to complete?

The easiest option is to simply increase the retry count, but that would again 
leave us with a fixed window of time for an operation to complete. It seems 
like something that monitors the balloon process, and continues to wait if it 
is progressing, might be a better approach.

Any ideas?


1. http://lists.xen.org/archives/html/xen-devel/2014-12/msg01443.html

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