Bug #8484
Implement aggregate sum and use for arc counters
| Status: | Closed | Start date: | 2017-07-11 | |
|---|---|---|---|---|
| Priority: | Normal | Due date: | ||
| Assignee: |  Prakash Surya | % Done: | 100% | |
| Category: | zfs - Zettabyte File System | |||
| Target version: | - | |||
| Difficulty: | Medium | Tags: | needs-triage |
Description
In pursuit of improving performance on multi-core systems, we should
implements fanned out counters and use them to improve the performance of
some of the arc statistics. These stats are updated extremely frequently,
and can consume a significant amount of CPU time.
History
#1
Updated by Dan McDonald 8 months ago
From its RTI:
We (Delphix) had an internal investigation of a case very similar to Dan McDonald's scenario shortly after the last RTI, where processes were spamming kstat grabbing in a tight loop. Of the CPU used by those processes, almost all of it was in the fork/exec loop, and only a small fraction was in the ioctl code. The amount of time spent in the arc or any other codepaths affected by this change was barely distinguishable from the steady-state operation of the system. As a result, I feel comfortable saying that this change does not increase the ability of a user to DoS the system by fetching kstats.
#2
Updated by Electric Monk 8 months ago
- % Done changed from 0 to 100
- Status changed from New to Closed
git commit 3a2d8a1b18794077eff4c504197c1d6f9d7ee487
commit 3a2d8a1b18794077eff4c504197c1d6f9d7ee487
Author: Paul Dagnelie <pcd@delphix.com>
Date: 2018-02-20T18:44:19.000Z
8484 Implement aggregate sum and use for arc counters
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>
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