The most time consuming part of running balancer, or calc_pg_upmaps in particular, that I can think of is the re-calculation of each pg mapping. For large clusters, that might take seconds even minutes to finish up. I think a more ideal fix would be introducing a pg mapping cache, e.g., we don't have to re-calculate all pg mappings if the osdmap epoch does not change, plus some methods to manipulate it the parallel way (https://github.com/ceph/ceph/pull/28373). 原始邮件 发件人：DavidZafman <dzafman(a)redhat.com> 收件人：谢型果10072465; 抄送人：ceph-devel <dev(a)ceph.io>io>; 日 期 ：2019年12月05日 06:43 主 题 ：upmaps and balancer Hi Xie, Pull request https://github.com/ceph/ceph/pull/31774 includes changes to the Balancer which I would like you to look at even though it has already merged. During testing I also uncovered an issue which I filed tracker https://tracker.ceph.com/issues/43124. Please have a look at the tracker. Thanks David