[pve-devel] [PATCH qemu-server 1/1] fix #4507 : increase qemu max openfiles limit

Fiona Ebner f.ebner at proxmox.com
Tue Dec 12 10:21:01 CET 2023

Am 11.12.23 um 17:29 schrieb DERUMIER, Alexandre:
>>> So not sure if that's really nicer. This suggests QEMU should raise
>>> the
>>> limit itself.
> Yes, but it don't raise the limit :/ But it's really working with more
> than 1024 file descriptor.

>From a quick look, I didn't find an option to pass along QEMU for this,
so it would likely need to be implemented first/discussed with upstream.
But thinking about it a bit, it feels wrong for each application to be
responsible for raising the limit itself. Sure the application needs to
avoid using select(), but IMHO such limits are better set from the
outside. I think your approach is fine, can you please send a v2 with a
Signed-off-by and my nits addressed?

I mean, ideally select() would just change to allow getting rid of the
low default limit, but the man page says it won't, so ¯\_(ツ)_/¯:

>        WARNING:  select()  can  monitor only file descriptors numbers that are less than FD_SETSIZE (1024)—an unreasonably low limit for
>        many modern applications—and this limitation will not change.  All modern applications should instead use  poll(2)  or  epoll(7),
>        which do not suffer this limitation.

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