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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2015-01-06 at 14:17 -0700, Mike Latimer wrote:
> Hi,
> 
> 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.

That's exactly what I was about to suggest as I read the penultimate
paragraph, i.e. keep waiting so long as some reasonable delta occurs on
each iteration.

Ian.

> 
> Any ideas?
> 
> Thanks,
> Mike
> 
> 1. http://lists.xen.org/archives/html/xen-devel/2014-12/msg01443.html
> 
> 
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