Fix ARC hit rate

Bug #1755158 reported by Colin Ian King on 2018-03-12
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Status tracked in Bionic
zfs-linux (Ubuntu)
Status tracked in Bionic
Colin Ian King

Bug Description

Upstream commit:

"When the compressed ARC feature was added in commit d3c2ae1
the method of reference counting in the ARC was modified. As
part of this accounting change the arc_buf_add_ref() function
was removed entirely.

This would have be fine but the arc_buf_add_ref() function
served a second undocumented purpose of updating the ARC access
information when taking a hold on a dbuf. Without this logic
in place a cached dbuf would not migrate its associated
arc_buf_hdr_t to the MFU list. This would negatively impact
the ARC hit rate, particularly on systems with a small ARC."

Changed in linux (Ubuntu):
importance: Undecided → Medium
assignee: nobody → Colin Ian King (colin-king)
status: New → In Progress
affects: linux (Ubuntu) → zfs-linux (Ubuntu)
Changed in zfs-linux (Ubuntu):
status: In Progress → Fix Committed
Changed in linux (Ubuntu Bionic):
status: New → Fix Committed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package zfs-linux - 0.7.5-1ubuntu6

zfs-linux (0.7.5-1ubuntu6) bionic; urgency=medium

  * Fix ARC hit rate (LP: #1755158)
    - Upstream fix, commit 0873bb6337452e3e028e40f5dad945b30deab185,
      fixes issue that can impact ARC hit rate especially with a
      small ARC

 -- Colin Ian King <email address hidden> Mon, 12 Mar 2018 12:40:22 +0000

Changed in zfs-linux (Ubuntu Bionic):
status: Fix Committed → Fix Released
To post a comment you must log in.
This report contains Public information  Edit
Everyone can see this information.

Other bug subscribers