Also, ceph server side, the new io_uring seem exciting too :) https://github.com/ceph/ceph/pull/27392
----- Mail original ----- De: "Thomas Lamprecht" <t.lampre...@proxmox.com> À: "pve-devel" <pve-devel@pve.proxmox.com>, "aderumier" <aderum...@odiso.com> Envoyé: Mercredi 25 Mars 2020 12:00:21 Objet: Re: [pve-devel] Ceph Octopus is out! On 3/25/20 11:17 AM, Alexandre DERUMIER wrote: > I'm pretty excited by the new write-around cache policy for librbd && io > scheduler:) > > (better than writeback, no read latency impact :) > Better for high perf. write workloads: > Writes return immediately under both the write-around and write-back > policies, > unless there are more than rbd cache max dirty unwritten bytes to the storage > cluster. The write-around policy differs from the write-back policy in that > it > does not attempt to service read requests from the cache, unlike the > write-back > policy, and is therefore faster for high performance write workloads. Under > the > write-through policy, writes return only when the data is on disk on all > replicas, but reads may come from the cache. -- https://docs.ceph.com/docs/octopus/rbd/rbd-config-ref/#cache-settings Not sure if all workloads benefit from that. > librbd now uses a write-around cache policy be default, > replacing the previous write-back cache policy default. > This cache policy allows librbd to immediately complete > write IOs while they are still in-flight to the OSDs. > Subsequent flush requests will ensure all in-flight > write IOs are completed prior to completing. The > librbd cache policy can be controlled via a new > “rbd_cache_policy” configuration option. > > librbd now includes a simple IO scheduler which attempts to > batch together multiple IOs against the same backing RBD > data block object. The librbd IO scheduler policy can be > controlled via a new “rbd_io_scheduler” configuration > option. Let's see how much this brings in performance :) _______________________________________________ pve-devel mailing list pve-devel@pve.proxmox.com https://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
