On Tue, 15 Oct 2019 at 20:15, Ning Yao <zay11022@xxxxxxxxx> wrote: > > Honggang(Joseph) Yang <eagle.rtlinux@xxxxxxxxx> 于2019年10月12日周六 上午12:04写道： >> >> Hi, >> >> We implemented a new cache tier mode - local mode. In this mode, an >> osd is configured to manage two data devices, one is fast device, one >> is slow device. Hot objects are promoted from slow device to fast >> device, and demoted from fast device to slow device when they become >> cold. >> >> > > I'm quite interesting about this and seems quite promising. But it seems objects level tier seems still not efficient enough in the small write scenario (4k ~ 8k based on your fio test result), right? > Now, in bluestore, it is possbile to implement a fine-grain local tier. it seems bluestore_pextent_t may be allocated from different devices and strategies like extent level hitset to evaluate whether some extents need to demote to slow devices. A promotion or demotion may submit a read with write operations in a transactions, and finished with a onode or blobs flushed into rocksdb. Tier local mode offers a more flexible mechanism for the up layer(rgw/cephfs/rbd) to participate the tier migration work. As for the performance test result, its highly dependent on the io pattern and quality of my code :) > >> The introduction of tier local mode in detail is >> https://tracker.ceph.com/issues/42286 >> >> tier local mode: https://github.com/yanghonggang/ceph/commits/wip-tier-new >> >> This work is based on ceph v12.2.5. I'm glad to port it to master >> branch if needed. >> >> Any advice and suggestions will be greatly appreciated. >> >> thx, >> >> Yang Honggang >> _______________________________________________ >> Dev mailing list -- dev@xxxxxxx >> To unsubscribe send an email to dev-leave@xxxxxxx _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
