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author | Bernhard Voelker <mail@bernhard-voelker.de> | 2014-09-16 18:50:29 +0200 |
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committer | Bernhard Voelker <mail@bernhard-voelker.de> | 2014-09-16 18:50:29 +0200 |
commit | ed0c3c33c6f7c28e5f05e96e1891251bdd181651 (patch) | |
tree | 4269f4af3469274c413b27f9ff55a14c3637cdf8 /tests/du/2g.sh | |
parent | 3b1ac4b1edd6f56155196ce79e6a58c652f03f2f (diff) | |
download | coreutils-ed0c3c33c6f7c28e5f05e96e1891251bdd181651.tar.xz |
tests: fix false du failure on newer XFS
On XFS, when creating the ~2G test file 'big' in a for-loop by
appending 20M each time, the file ends up using ~4G - visible in
'st_blocks'. The unused space would be reclaimed later.
This feature is called "speculative preallocation" which aims at
avoiding fragmentation.
According to the XFS FAQ [1], there are two particular aspects of
XFS speculative preallocation that are triggering this:
1. "Applications that repeatedly trigger preallocation and reclaim
cycles [after file close] can cause fragmentation.
Therefore, this pattern is detected and causes the preallocation
to persist beyond the lifecycle of the file descriptor."
2. "Preallocation sizes grow as files grow larger."
[1] http://xfs.org/index.php/XFS_FAQ
Avoid one of the above by only doing a single close (reclaim cycle).
* tests/du/2g.sh: Similar to the fix for a dd test (see commit
v8.22-65-g7c03fe2), avoid speculative preallocation by creating
the 'big' file in one go instead of appending to it in the loop.
Remove debugging statements as the output with 'set -x' is
sufficient nowadays.
Diffstat (limited to 'tests/du/2g.sh')
-rwxr-xr-x | tests/du/2g.sh | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/tests/du/2g.sh b/tests/du/2g.sh index f766d4d9d..d7cc987d0 100755 --- a/tests/du/2g.sh +++ b/tests/du/2g.sh @@ -43,15 +43,14 @@ test $min_kb -lt $free_kb || big=big rm -f $big -test -t 1 || printf 'creating a 2GB file...\n' -for i in $(seq 100); do - # Note: 2147483648 == 2^31. Print floor(2^31/100) per iteration. - printf %21474836s x >> $big || fail=1 - # On the final iteration, append the remaining 48 bytes. - test $i = 100 && { printf %48s x >> $big || fail=1; } - test -t 1 && printf 'creating a 2GB file: %d%% complete\r' $i -done -echo +{ + for i in $(seq 100); do + # Note: 2147483648 == 2^31. Print floor(2^31/100) per iteration. + printf %21474836s x || fail=1 + done + # After the final iteration, append the remaining 48 bytes. + printf %48s x || fail=1 +} > $big || fail=1 du -k $big > out1 || fail=1 rm -f $big |