On 30/10/2024 17:49, Friedrich Weber wrote: > [...] > > Yeah, I see the point. > > Of course, another alternative is enabling `rxbounce` unconditionally, > as initially requested in [1]. I'm a hesitant to do that because from > reading its description I'd expect it could have a performance impact -- > it's probably small, if any, but this should probably be checked before > changing the default. >
I took another look at this: When rxbounce was first introduced, there was a discussion whether krbd could enabled automatically switch to "rxbounce mode" if needed [0]. I asked upstream whether this seems realistic [1], and they responded it's very unlikely to happen. So the cleanest solution from a user point of view might be if PVE automatically passes rxbounce only when mapping disks of Windows VMs. But as Fabian points out [2], this would require some way to pass this information to the storage layer. Of course always passing rxbounce is still an option. Upstream confirmed there is a theoretical performance impact, but it might be negligible in practice [0]. So if benchmarks show the impact is indeed negligible, we could go for that route. But even with benchmarks done carefully, there is a chance that they fail to catch a performance impact on some types of workloads. So in order to not disturb setups that currently work fine without rxbounce, I have a slight preference for only passing rxbounce when needed, even if that requires some architectural changes. [0] https://lore.kernel.org/all/894a36483c241e0cc5154e09e8dd078f57a606d5.ca...@kernel.org/ [1] https://lists.ceph.io/hyperkitty/list/ceph-us...@ceph.io/message/ZSXCXPTLMQPV27Y7I375OBR7CN56LDGH/ [2] https://lore.proxmox.com/pve-devel/1234079298.5156.1730294987...@webmail.proxmox.com/ _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
