On Sat, Aug 28, 2021 at 10:21:37AM +1000, Chris Dunlop wrote:
On Sat, Aug 28, 2021 at 08:03:43AM +1000, Dave Chinner wrote:
commit fd43cf600cf61c66ae0a1021aca2f636115c7fcb
Author: Brian Foster <bfoster@xxxxxxxxxx>
Date: Wed Apr 28 15:06:05 2021 -0700
xfs: set aside allocation btree blocks from block reservation
Oh wow. Yes, sounds like a candidate. Is there same easy(-ish?) way of
seeing if this fs is likely to be suffering from this particular issue
or is it a matter of installing an appropriate kernel and seeing if
the problem goes away?
Is this sufficient to tell us that this filesystem probably isn't suffering
from that issue?
$ sudo xfs_db -r -c 'freesp -s' /dev/mapper/vg00-chroot
from to extents blocks pct
1 1 74943 74943 0.00
2 3 71266 179032 0.01
4 7 155670 855072 0.04
8 15 304838 3512336 0.17
16 31 613606 14459417 0.72
32 63 1043230 47413004 2.35
64 127 1130921 106646418 5.29
128 255 1043683 188291054 9.34
256 511 576818 200011819 9.93
512 1023 328790 230908212 11.46
1024 2047 194784 276975084 13.75
2048 4095 119242 341977975 16.97
4096 8191 72903 406955899 20.20
8192 16383 5991 67763286 3.36
16384 32767 1431 31354803 1.56
32768 65535 310 14366959 0.71
65536 131071 122 10838153 0.54
131072 262143 87 15901152 0.79
262144 524287 44 17822179 0.88
524288 1048575 16 12482310 0.62
1048576 2097151 14 20897049 1.04
4194304 8388607 1 5213142 0.26
total free extents 5738710
total free blocks 2014899298
average free extent size 351.107
Or from:
How to tell how fragmented the free space is on an XFS filesystem?
https://www.suse.com/support/kb/doc/?id=000018219
Based on xfs_info "agcount=32":
$ {
for AGNO in {0..31}; do
sudo /usr/sbin/xfs_db -r -c "freesp -s -a $AGNO" /dev/mapper/vg00-chroot > /tmp/ag${AGNO}.txt
done
grep -h '^average free extent size' /tmp/ag*.txt | sort -k5n | head -n5
echo --
grep -h '^average free extent size' /tmp/ag*.txt | sort -k5n | tail -n5
}
average free extent size 66.7806
average free extent size 79.201
average free extent size 80.221
average free extent size 87.595
average free extent size 103.079
--
average free extent size 898.962
average free extent size 906.709
average free extent size 1001.18
average free extent size 1849.23
average free extent size 2782.75
Even those ags with the lowest average free extent size are higher than what
the web page suggests is "an AG in fairly good shape".
Cheers,
Chris
