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Date:      Sat, 23 Nov 2013 03:26:13 -0500
From:      Eitan Adler <lists@eitanadler.com>
To:        "freebsd-fs@freebsd.org" <fs@freebsd.org>
Subject:   ZFS (or something) is absurdly slow
Message-ID:  <CAF6rxgmepSN9pFPH%2BQiLaNqhzXxkXwu=59zvfD-6gGEMg9zh1g@mail.gmail.com>

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Every so often I see absurdly slow tasks stuck on "zio->io_cv".

For example a recent "git checkout file.c" did not complete for many minutes
load: 0.65  cmd: git 74577 [zio->io_cv] 435.58r 0.20u 2.54s 0% 71488k

I have seen "ls ~" take tends of minutes to complete.  Even "ls
/var/empty" can take just as long.  This length of time is variable
but is usually much longer than expected.

Does anyone have any suggestions for helping to figure out what is
taking a long time?

I have two disks: a tiny 16GB SSD I use for boot and the root FS.   I
also have a 1TB HDD I use for my ~ and other data:
=>      34  31277165  ada0  GPT  (15G)
        34       222     1  freebsd-boot  (111K)
       256  31276943     2  freebsd-zfs  (15G)

=>        34  1953525101  ada1  GPT  (932G)
          34          94        - free -  (47K)
         128    33554432     1  freebsd-swap  (16G)
    33554560  1919970560     2  freebsd-zfs  (916G)
  1953525120          15        - free -  (7.5K)

[10014 eitan@gravity (100%) ~ !2!]%time zfs list
NAME                                USED  AVAIL  REFER  MOUNTPOINT
zdata                               278G   620G    31K  none
zdata/cache                        3.08G   620G  3.08G  /cache
zdata/compresseddisk                106G   620G   106G  /root/compresseddisk
zdata/debug                         711M   620G   711M  /usr/lib/debug
zdata/distfiles                    15.2G   620G  15.2G  /data/distfiles
zdata/home                          124G   620G  71.2G  /home
zdata/home/eitan                   52.9G   620G    34K  none
zdata/home/eitan/svn               52.9G   620G  51.3G  /home/eitan/svn
zdata/home/eitan/svn/ports_master  1.56G   620G  1.56G
/home/eitan/svn/fbsd/ports
zdata/local                        3.24G   620G  3.24G  /usr/local
zdata/obj                          11.5G   620G  11.5G  /usr/obj
zdata/ports                        4.21G   620G  4.21G  /usr/ports
zdata/poudriere                    4.91G   620G    31K  none
zdata/poudriere/data               1.10G   620G  1.10G
/usr/local/poudriere/data
zdata/poudriere/jails              3.81G   620G    31K  none
zdata/poudriere/jails/83amd64       795M   620G   795M
/usr/local/poudriere/jails/83amd64
zdata/poudriere/jails/91amd64      1.03G   620G  1.03G
/usr/local/poudriere/jails/91amd64
zdata/poudriere/jails/91i386        961M   620G   961M
/usr/local/poudriere/jails/91i386
zdata/poudriere/jails/92amd64      1.07G   620G  1.07G
/usr/local/poudriere/jails/92amd64
zdata/src                           578M   620G   578M  /usr/src
zdata/work                         4.88G   620G  4.88G  /work
zroot                              3.53G  11.1G  2.23G  /
zroot/tmp                           154M  11.1G   154M  none
zroot/usr                           715M  11.1G   715M  /usr
zroot/var                           455M  11.1G  80.9M  /var
zroot/var/db                        373M  11.1G   373M  /var/db
zroot/var/empty                      31K  11.1G    31K  /var/empty
zroot/var/tmp                      1022K  11.1G  1022K  /var/tmp
zfs list  0.02s user 0.01s system 0% cpu 9.076 total

[10009 eitan@gravity (100%) ~ !2!]%time zpool list
NAME        SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
zdata       912G   278G   634G    30%  1.00x  ONLINE  -
zexternal      -      -      -      -      -  FAULTED  -
zroot      14.9G  3.53G  11.3G    23%  1.00x  ONLINE  -
zpool list  0.00s user 0.01s system 0% cpu 2.192 total

[10019 eitan@gravity (100%) ~ ]%uname -a
FreeBSD gravity.local 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r258140M:
Thu Nov 14 17:04:27 EST 2013
eitan@gravity.local:/usr/obj/usr/src/sys/EADLER  amd64

FWIW, this kernel is compiled with INVARIANTS but without WITNESS.
MALLOC_PRODUCTION is enabled.

-- 
Eitan Adler



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