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Feature #4930
openOSD: replica to primary back pressure
Status:
New
Priority:
Normal
Assignee:
-
Category:
-
Target version:
-
% Done:
0%
Source:
other
Tags:
Backport:
Reviewed:
Affected Versions:
Component(RADOS):
OSD
Pull request ID:
Description
Currently, replicas cannot throttle sub-ops. This means that a slower OSD can have OSDOps starved by sub-ops.
Updated by Samuel Just almost 11 years ago
This can probably be done in a few steps:
1 Add OSDService::estimate_delay() which returns an estimate of latency for a small write.
2 expose above via admin_socket and osd_stat for visibility
3 piggy-back the current delay on MOSDSubOp and MOSDPing as a way of allowing each OSD to build maps of peer delay estimates.
4 Rate limit sub-ops sent to any single at a rate which is a function of the current delay
- the goal is keep the peer saturated, but back off once latency starts to increase
1 & 2 are useful for visibility purposes independent of the overall task.
Updated by Patrick Donnelly about 5 years ago
- Project changed from Ceph to RADOS
- Category deleted (
OSD) - Component(RADOS) OSD added
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