(docs) CP-53645 on xenguest: Add walk-through on claiming and populating VM memory #6373
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Signed-off-by: Bernhard Kaindl <[email protected]>
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This is done as part of CP-53645 for NUMA, and my next task is to improve the documentation further to document the design of NUMA memory allocations (developed in parallel). A preview of this PR is at If you have any comments, I will be able to incorporate them during review and also in the followup work. |
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| title: Libraries | |||
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| title: Libraries | |
| title: C Libraries in Xen |
| > Errors returned by `xc_domain_claim_pages()` must be handled as they are a | ||
| normal result of the `xenopsd` thread-pool claiming and starting many VMs | ||
| in parallel during a boot storm scenario. |
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Why would it be a normal result for xenopsd? the toolstack does memory accounting to avoid these kind of errors
| > [!warning] | ||
| > This is especially important when staking claims on NUMA nodes using an updated | ||
| version of this function. In this case, the only options of the calling worker | ||
| thread would be to adapt to the NUMA boot storm: | ||
| Attempt to find a different NUMA node for claiming the memory and try again. |
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The xenopsd code already reads the amount of available memory under a lock to select how much memory per-node it should assign to a VM. Unless there are other toolstacks starting VMs, this won't happen. So expecting a failure and retrying is not how xenopsd is working.
| the domain. | ||
| is updated to call an updated version of this function for the domain. | ||
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| It reserves NUMA node memory before `xenguest` is called, and a new `pnode` |
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The parameter name is -mem_pnode
Documentation to understand the current implementation
for claiming and populating VM memory when building a
domain from
xenopsd.The focus is on claiming the memory and allocating
and populating the boot memory using
xenguest.