On 2/9/23 20:28, Bharata B Rao wrote: > On 2/9/2023 7:58 PM, Dave Hansen wrote: >> On 2/8/23 22:04, Bharata B Rao wrote: >>>> First, IIRC, Intel PEBS at the time only gave guest virtual addresses in >>>> the PEBS records. They had to be translated back to host addresses to >>>> be usable. That was extra expensive. >>> Just to be clear, I am using IBS in host only and it can give both virtual >>> and physical address. >> Could you talk a little bit about how IBS might get used for NUMA >> balancing guest memory? > IBS can work for guest, but will not provide physical address. Also > the support for virtualized IBS isn't upstream yet. > > However I am not sure how effective or useful NUMA balancing within a guest > is, as the actual physical addresses are transparent to the guest. > > Additionally when using IBS in host, it is possible to prevent collection > of samples from secure guests by using the PreventHostIBS feature. > (https://lore.kernel.org/linux-perf-users/20230206060545.628502-1-manali.shukla@xxxxxxx/T/#) I was wondering specifically about how a host might use IBS to balance guest memory transparently to the guest. Now how a guest might use IBS to balance its own memory.
