Am 06/10/2023 um 14:15 schrieb Friedrich Weber: > The default VM startup timeout is `max(30, VM memory in GiB)` seconds. > Multiple reports in the forum [0] [1] and the bug tracker [2] suggest > this is too short when using PCI passthrough with a large amount of VM > memory, since QEMU needs to map the whole memory during startup (see > comment #2 in [2]). As a result, VM startup fails with "got timeout". > > To work around this, set a larger default timeout if at least one PCI > device is passed through. The question remains how to choose an > appropriate timeout. Users reported the following startup times: > > ref | RAM | time | ratio (s/GiB) > --------------------------------- > [1] | 60G | 135s | 2.25 > [1] | 70G | 157s | 2.24 > [1] | 80G | 277s | 3.46 > [2] | 65G | 213s | 3.28 > [2] | 96G | >290s | >3.02 > > The data does not really indicate any simple (e.g. linear) > relationship between RAM and startup time (even data from the same > source). However, to keep the heuristic simple, assume linear growth > and multiply the default timeout by 4 if at least one `hostpci[n]` > option is present, obtaining `4 * max(30, VM memory in GiB)`. This > covers all cases above, and should still leave some headroom. > > [0]: https://forum.proxmox.com/threads/83765/post-552071 > [1]: https://forum.proxmox.com/threads/126398/post-592826 > [2]: https://bugzilla.proxmox.com/show_bug.cgi?id=3502 > > Suggested-by: Fiona Ebner <f.eb...@proxmox.com> > Signed-off-by: Friedrich Weber <f.we...@proxmox.com> > --- > > Notes: > changes since v1 (was called "vm start: set minimum timeout of 300s if > using PCI passthrough", 20230503133723.165739-1-f.we...@proxmox.com): > * Use a constant multiplier as suggested by Fiona (thx!) > > Another workaround is offered by an unapplied patch series [3] of bug > 3502 [2] that makes it possible to set VM-specific timeouts (also in > the GUI). Users could use this option to manually set a higher > timeout for VMs that use PCI passthrough. However, it is not > immediately obvious that a higher timeout is necessary when using > PCI passthrough. Since the problem seems to come up somewhat > frequently, I think it makes sense to have the heuristic choose a > higher timeout by default.
yeah, I think so too. > > As discussed in v1, I'll also pick up the patch series to allow users > to set custom timeouts [3], also to offer a workaround for cases where > the new heuristic chooses a timeout that is still too short. > > [2]: https://bugzilla.proxmox.com/show_bug.cgi?id=3502 > [3]: > https://lists.proxmox.com/pipermail/pve-devel/2023-January/055352.html > > PVE/QemuServer/Helpers.pm | 7 +++++++ > 1 file changed, 7 insertions(+) > > applied, thanks! _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
