Bug #184

zfs_putpage() optimization

Added by Bryan Leaman about 5 years ago. Updated over 4 years ago.

Status:ResolvedStart date:2010-09-11
Priority:NormalDue date:
Assignee:Garrett D'Amore% Done:


Target version:-
Difficulty: Tags:


This has been logged as CR 6979725 but not yet fixed by Oracle.

I experienced the issue during a filebench run on Nexenta in which the file "re-use" operation (msync) on a 20GB file caused all I/O to hang for more than 30 seconds, even other zpools. Stack trace looked like this:

[ ffffff0010429990 _resume_from_idle+0xf1() ]
ffffff0010429b10 page_lookup_create+0xd6(ffffff02d2813c40, 37588b000, 1, 0, 0, 0)
ffffff0010429b40 page_lookup+0x26(ffffff02d2813c40, 375889000, 1)
ffffff0010429c00 zfs_putpage+0x1af(ffffff02d2813c40, 3758a5000, 1000, 10000, ffffff02cf328f20, 0)
ffffff0010429c70 fop_putpage+0x74(ffffff02d2813c40, 3758b0000, 1000, 10000, ffffff02cf328f20, 0)
ffffff0010429d50 segvn_sync+0x459(ffffff02ecb4e7f0, fffffd7f63c00000, 40000000, 0, 6)
ffffff0010429e40 as_ctl+0x200(ffffff02d15efda0, fffffd7f63c00000, 40000000, 1, 0, 6, 0, 0)
ffffff0010429f00 memcntl+0x764(fffffd7f63c00000, 40000000, 1, 2, 0, 0)
ffffff0010429f10 sys_syscall+0x17a()

I created the attached patch and re-ran the filebench tests, and the long I/O stalls were reduced to only 3 or 4 seconds. I'm creating this issue report since the problem most likely exists in Illumos as well. Looking for comments/feedback on whether this fix seems correct and appropriate. Thanks!

zfs_putpage-optimization-6979725.patch Magnifier (593 Bytes) Bryan Leaman, 2010-09-11 08:16 AM


#1 Updated by Garrett D'Amore over 4 years ago

  • Category set to kernel
  • Status changed from New to In Progress
  • Assignee set to Garrett D'Amore
  • % Done changed from 0 to 90

The patch looks good, and the ZFS working group members have blessed the change, with one suggestion (the insertion of an ASSERT at the right point.)

#2 Updated by Garrett D'Amore over 4 years ago

  • Status changed from In Progress to Resolved
  • % Done changed from 90 to 100

garrett@thinkpad{31}> hg head
changeset: 13283:4f8f71d21b9f
tag: tip
user: Garrett D'Amore <>
date: Mon Feb 07 14:16:27 2011 -0800
184 zfs_putpage() optimization
Reviewed by:
Reviewed by:
Approved by:

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