The Monday 21 Jul 2014 à 08:59:45 (-0600), Chris Friesen wrote : > On 07/19/2014 02:45 AM, Benoît Canet wrote: > > >I think in the throttling case the number of in flight operation is limited > >by > >the emulated hardware queue. Else request would pile up and throttling would > >be > >inefective. > > > >So this number should be around: #define VIRTIO_PCI_QUEUE_MAX 64 or > >something like than that. > > Okay, that makes sense. Do you know how much data can be written as part of > a single operation? We're using 2MB hugepages for the guest memory, and we > saw the qemu RSS numbers jump from 25-30MB during normal operation up to > 120-180MB when running dbench. I'd like to know what the worst-case would > be.
I think Linux as a limit of 512Kb for io size or something like that. So the guest would have VIRTIO_PCI_QUEUE_MAX * 512Kb of in flight buffers at max. > > Thanks, > Chris
