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Bug #14760

open

Reduce ZIO io_lock contention on sorted scrub

Added by Toomas Soome 13 days ago. Updated 13 days ago.

Status:
In Progress
Priority:
Normal
Assignee:
Category:
zfs - Zettabyte File System
Start date:
Due date:
% Done:

90%

Estimated time:
Difficulty:
Medium
Tags:
Gerrit CR:

Description

Update from OpenZFS:

    During sorted scrub multiple threads (one per vdev) are issuing many
    ZIOs same time, all using the same scn->scn_zio_root ZIO as parent.
    It causes huge lock contention on the single global lock on that ZIO.
    Improve it by introducing per-queue null ZIOs, children to that one,
    and using them instead as proxy.

    For 12 SSD pool storing 1.5TB of 4KB blocks on 80-core system this
    dramatically reduces lock contention and reduces scrub time from 21
    minutes down to 12.5, while actual read stages (not scan) are about
    3x faster, reaching 100K blocks per second per vdev.

    Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
    Signed-off-by: Alexander Motin <mav@FreeBSD.org>
    Sponsored-By: iXsystems, Inc.
    Closes #13553

Actions #1

Updated by Electric Monk 13 days ago

  • Gerrit CR set to 2201
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