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Feature #3335

make SYNC_PASS_* constants tunable

Added by Christopher Siden about 8 years ago. Updated about 8 years ago.

Status:
Closed
Priority:
Normal
Category:
zfs - Zettabyte File System
Start date:
2012-11-01
Due date:
% Done:

0%

Estimated time:
Difficulty:
Medium
Tags:
needs-triage
Gerrit CR:

Description

There are several SYNC_PASS_* constants that affect the performance of spa_sync(). We have already seen one of these values be clearly sub-optimal (bug 3331). We should make these values tunable to allow some performance analysis to be done. There should be a comment by the tunables warning against tuning these values for anything other than performance analysis since it could lead to subtle and pathological performance problems. Once we have done sufficient analysis these values should be changed back to #defines.


Related issues

Related to illumos gate - Bug #3331: deferred frees should happen after sync_pass 1ClosedChristopher Siden2012-10-31

Actions
#1

Updated by Christopher Siden about 8 years ago

  • Status changed from In Progress to Closed
commit 01f55e48fb4d524eaf70687728aa51b7762e2e97
Author: George Wilson <george.wilson@delphix.com>
Date:   Wed Nov 7 14:05:17 2012 -0800

    3329 spa_sync() spends 10-20% of its time in spa_free_sync_cb()
    3330 space_seg_t should have its own kmem_cache
    3331 deferred frees should happen after sync_pass 1
    3335 make SYNC_PASS_* constants tunable
    Reviewed by: Adam Leventhal <ahl@delphix.com>
    Reviewed by: Matt Ahrens <matthew.ahrens@delphix.com>
    Reviewed by: Christopher Siden <chris.siden@delphix.com>
    Reviewed by: Eric Schrock <eric.schrock@delphix.com>
    Reviewed by: Richard Lowe <richlowe@richlowe.net>
    Reviewed by: Dan McDonald <danmcd@nexenta.com>
    Approved by: Eric Schrock <eric.schrock@delphix.com>

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