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Date:      Sun, 16 Oct 2022 21:55:21 +0200
From:      Mateusz Guzik <mjguzik@gmail.com>
To:        void <void@f-m.fm>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: zfs with operations like rm -rf takes a very long time recently
Message-ID:  <CAGudoHGsXT2C74bzDDzmB3U5KS3vMBarGJ%2BFd6nXxUyswdZfpQ@mail.gmail.com>
In-Reply-To: <f25d069a-2ee7-491a-a5ef-a14b973c12e2@app.fastmail.com>
References:  <f25d069a-2ee7-491a-a5ef-a14b973c12e2@app.fastmail.com>

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On 10/16/22, void <void@f-m.fm> wrote:
> Has anything recently changed in -current that would make file operations
> on zfs such as rm -rf *.* very slow?
>
> What would I look for and how would I test it?
>
> system is FreeBSD 14.0-CURRENT #5 main-n258595-226e41467ee1 on
> arm64.aarch64
> using GENERIC-NODEBUG kernel.
>
> the zfs is zroot on usb3 on a raspberry pi4 8GB. there appears to be plenty
>
> of resources. cpu speed is 2.1GHz. zroot is external usb3 hd.
>
> Right now it's rm -rf-ing /var/cache/ccache/* which is 5GB max and it's
> taken
> over 10 mins. It was never this slow. No errors in /var/log/messages and
> none
> yet in smartd. zpool scrub last ran successfully 3 days ago.
>
> last pid:  4324;  load averages:  0.17,  0.10,  0.12
>                              up 0+02:10:34  14:40:55
> 77 processes:  1 running, 76 sleeping
> CPU:  1.6% user,  0.0% nice,  1.9% system,  0.2% interrupt, 96.4% idle
> Mem: 550M Active, 803M Inact, 2224M Wired, 40K Buf, 4239M Free
> ARC: 1293M Total, 381M MFU, 725M MRU, 1124K Anon, 30M Header, 156M Other
>      938M Compressed, 1906M Uncompressed, 2.03:1 Ratio
> Swap: 16G Total, 16G Free
> Process id to show (+ for all):
>   PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU
> COMMAND
>  3871 root          1  20    0    12M  3648K zio->i   2   0:10   0.39% rm
>   353 _pflogd       1  20    0    13M  2108K bpf      1   0:00   0.00%
> pflogd
>  1441 mailnull      1  28    0    25M  9508K select   3   0:01   0.00% exim
>

Just in case, can you test with this: sysctl
vfs.zfs.per_txg_dirty_frees_percent=5

As in, can you repeat the test multiple times, flipping
vfs.zfs.per_txg_dirty_frees_percent between 5 and 30.

-- 
Mateusz Guzik <mjguzik gmail.com>



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