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Bug 1514504 - [RFE] Implement rocksdb cache perf counter
Summary: [RFE] Implement rocksdb cache perf counter
Alias: None
Product: Red Hat Ceph Storage
Classification: Red Hat
Component: RADOS
Version: 2.4
Hardware: x86_64
OS: All
Target Milestone: rc
: 3.*
Assignee: Josh Durgin
QA Contact: ceph-qe-bugs
Depends On:
TreeView+ depends on / blocked
Reported: 2017-11-17 15:35 UTC by Vikhyat Umrao
Modified: 2019-03-08 04:10 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2019-03-08 04:10:14 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Ceph Project Bug Tracker 22152 None None None 2017-11-17 15:43:48 UTC

Description Vikhyat Umrao 2017-11-17 15:35:01 UTC
Description of problem:
Implement rocksdb cache perf counter

Maybe we can use ceph daemon osd.$id perf dump and add rocksdb cache perf counter:

1. rocksdb cache full or not
2. how many omap keys it has 
3. How many times it became full and flush?
4. any other important information

Version-Release number of selected component (if applicable):
Red Hat Ceph Storage 2.4

Right now perf dump covers the following:

  "rocksdb": {
        "rocksdb_get": 9798,
        "rocksdb_transaction": 518732,
        "rocksdb_get_latency": {
            "avgcount": 9798,
            "sum": 54.697089911
        "rocksdb_submit_latency": {
            "avgcount": 505433,
            "sum": 15.398420482
        "rocksdb_submit_sync_latency": {
            "avgcount": 13299,
            "sum": 12.566100383
        "rocksdb_compact": 0,
        "rocksdb_compact_range": 0,
        "rocksdb_compact_queue_merge": 0,
        "rocksdb_compact_queue_len": 0

Maybe we can add rocksdb cache here.

Comment 2 Greg Farnum 2019-03-08 04:10:14 UTC
We haven't ever wanted this information, including when Mark built the BlueStore auto-tuning cache stuff. The specifically-named values don't make much sense either — it is in the nature of an SST cache to always be full and flushing something (especially under compaction); it doesn't track specific key counts but rather ranges of level files; etc.

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