CA-423173: XAPI underestimates low memory emergency pool size #6855
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lindig
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Jan 22, 2026
cplaursen
approved these changes
Jan 22, 2026
The only Xen command-line related to this is `low_mem_virq_limit`, which is 64MiB. A new quicktest has shown that we are sometimes off by ~10MiB or more, and get failures booting VMs even after `assert_can_boot_here` said yes. Sometimes the error messages can be quite ugly, internal xenguest/xenopsd errors, instead of HOST_NOT_ENOUGH_FREE_MEMORY. Signed-off-by: Edwin Török <edwin.torok@citrix.com>
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The only Xen command-line related to this is
low_mem_virq_limit, which is 64MiB.A new quicktest has shown that we are sometimes off by ~10MiB (between
Host.compute_free_memoryand actual free memory as measured by a call to Xenctrl physinfo) or more, and get failures booting VMs even afterassert_can_boot_heresaid yes. Sometimes the error messages can be quite ugly, internal xenguest/xenopsd errors, instead of HOST_NOT_ENOUGH_FREE_MEMORY.After this change (together with #6854) the new quicktest doesn't fail anymore.
PR to feature branch because this will need testing together with all the other NUMA changes, it may expose latent bugs elsewhere.
The new testcase will get its own PR because it is quite large.