Steven Noonan

In the Part 3 of this series, we walked through the Xen paravirtual I/O architecture and what makes it expensive on a Non-Uniform Memory Access (NUMA) host: foreign-mapped pages with no NUMA metadata, kthreads landing wherever the scheduler happened to put them, an information gap between the dom0 kernel and the host's actual topology. We closed that part on a promise that the fix has two pieces - a structural one and a per-component one - and that part 4 would deliver both.

Two virtual machines on the same host, configured identically, running the same workload. One of them is 20% slower than the other, consistently. Nothing is wrong with the workload, nothing is wrong with the host, no contention from other tenants. The slow one's memory just happens to be on the wrong side of an interconnect from the CPUs running it, and there is no in-guest knob the operator can turn to fix it. That is the story this series is about.

linux-kernel.vger.kernel.org archive mirror help / color / mirror / Atom feed From: Huang Rui <ray.huang@amd.com> To: Shuah Khan <skhan@linuxfoundation.org>, "Rafael J .