Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin

Jason Gunthorpe
2021-02-10T18:15:46Z

On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote:

> The problem is that SVA declares we can use any memory of a process
> to do I/O. And in real scenarios, we are unable to customize most
> applications to make them use the pool. So we are looking for some
> extension generically for applications such as Nginx, Ceph.

But those applications will suffer jitter even if their are using CPU
to do the same work. I fail to see why adding an accelerator suddenly
means the application owner will care about jitter introduced by
migration/etc.

Again in proper SVA it should be quite unlikely to take a fault caused
by something like migration, on the same likelyhood as the CPU. If
things are faulting so much this is a problem then I think it is a
system level problem with doing too much page motion.

Jason