On Tue, May 07, 2019 at 03:56:49PM -0300, Marcelo Tosatti wrote: > > Certain workloads perform poorly on KVM compared to baremetal > due to baremetal's ability to perform mwait on NEED_RESCHED > bit of task flags (therefore skipping the IPI). > > This patch introduces a configurable busy-wait delay before entering the > architecture delay routine, allowing wakeup IPIs to be skipped > (if the IPI happens in that window). > > The real-life workload which this patch improves performance > is SAP HANA (by 5-10%) (for which case setting idle_spin to 30 > is sufficient). > > This patch improves the attached server.py and client.py example > as follows: > > Host: 31.814230202231556 > Guest: 38.17718765199993 (83 %) > Guest, idle_spin=50us: 33.317709898000004 (95 %) > Guest, idle_spin=220us: 32.27826551499999 (98 %) > > Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Thanks for the CC.. NAK, this is something that should live in a virt idle governor or something along those lines.
