| Message ID | 20210426145620.1174139-1-bxue@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] generic/563: tolerate small reads in "write -> read/write" sub-test | expand |
On Mon, Apr 26, 2021 at 10:56:20PM +0800, bxue@redhat.com wrote: > From: Boyang Xue <bxue@redhat.com> > > On ext2/ext3, it's expected that several single block metadata reads can occur > when writing to file in the same cgroup (the stack is like below[1]). The > purpose of the "write -> read/write" subtest is to make sure the larger pwrite > is accounted to the correct cgroup, not necessarily enforce that zero bytes are > read in service of the write. This patch fixes the sub-test in order to tolerate > small reads in 1st cgroup. > > [1] Callchain of the read: > > @ext3_read_bio[ > submit_bio+1 > submit_bh_wbc+365 > ext4_read_bh+72 > ext4_get_branch+201 > ext4_ind_map_blocks+382 > ext4_map_blocks+295 > _ext4_get_block+170 > __block_write_begin_int+328 > ext4_write_begin+541 > generic_perform_write+213 > ext4_buffered_write_iter+167 > new_sync_write+345 > vfs_write+438 > __x64_sys_pwrite64+140 > do_syscall_64+51 > entry_SYSCALL_64_after_hwframe+68 > , 5793, 12]: 3 > > Signed-off-by: Boyang Xue <bxue@redhat.com> > --- LGTM, thanks for the fixups: Reviewed-by: Brian Foster <bfoster@redhat.com> > Hi, > > This patch fix the "write -> read/write" sub-test in order to tolerate > small reads in service of the write (like read metadata). > > Change from v2: > Restore write tolerance to 5%, to match the historical behavior of the > test. > > Thanks, > Boyang > > tests/generic/563 | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/tests/generic/563 b/tests/generic/563 > index b113eacf..e73acebd 100755 > --- a/tests/generic/563 > +++ b/tests/generic/563 > @@ -60,6 +60,8 @@ check_cg() > cgname=$(basename $cgroot) > expectedread=$2 > expectedwrite=$3 > + readtol=$4 > + writetol=$5 > rbytes=0 > wbytes=0 > > @@ -71,8 +73,8 @@ check_cg() > awk -F = '{ print $2 }'` > fi > > - _within_tolerance "read" $rbytes $expectedread 5% -v > - _within_tolerance "write" $wbytes $expectedwrite 5% -v > + _within_tolerance "read" $rbytes $expectedread $readtol -v > + _within_tolerance "write" $wbytes $expectedwrite $writetol -v > } > > # Move current process to another cgroup. > @@ -113,7 +115,7 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" -c fsync \ > $SCRATCH_MNT/file >> $seqres.full 2>&1 > switch_cg $cgdir > $XFS_IO_PROG -c fsync $SCRATCH_MNT/file > -check_cg $cgdir/$seq-cg $iosize $iosize > +check_cg $cgdir/$seq-cg $iosize $iosize 5% 5% > > # Write from one cgroup then read and write from a second. Writes are charged to > # the first group and nothing to the second. > @@ -126,8 +128,12 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" $SCRATCH_MNT/file \ > >> $seqres.full 2>&1 > switch_cg $cgdir > $XFS_IO_PROG -c fsync $SCRATCH_MNT/file > -check_cg $cgdir/$seq-cg 0 $iosize > -check_cg $cgdir/$seq-cg-2 0 0 > +# Use a fixed value tolerance for the expected value of zero here > +# because filesystems might perform a small number of metadata reads to > +# complete the write. On ext2/3 with 1k block size, the read bytes is > +# as large as 33792. > +check_cg $cgdir/$seq-cg 0 $iosize 33792 5% > +check_cg $cgdir/$seq-cg-2 0 0 0 0 > > # Read from one cgroup, read & write from a second. Both reads and writes are > # charged to the first group and nothing to the second. > @@ -140,8 +146,8 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" $SCRATCH_MNT/file \ > >> $seqres.full 2>&1 > switch_cg $cgdir > $XFS_IO_PROG -c fsync $SCRATCH_MNT/file > -check_cg $cgdir/$seq-cg $iosize $iosize > -check_cg $cgdir/$seq-cg-2 0 0 > +check_cg $cgdir/$seq-cg $iosize $iosize 5% 5% > +check_cg $cgdir/$seq-cg-2 0 0 0 0 > > echo "-io" > $cgdir/cgroup.subtree_control || _fail "subtree control" > > -- > 2.27.0 >
diff --git a/tests/generic/563 b/tests/generic/563 index b113eacf..e73acebd 100755 --- a/tests/generic/563 +++ b/tests/generic/563 @@ -60,6 +60,8 @@ check_cg() cgname=$(basename $cgroot) expectedread=$2 expectedwrite=$3 + readtol=$4 + writetol=$5 rbytes=0 wbytes=0 @@ -71,8 +73,8 @@ check_cg() awk -F = '{ print $2 }'` fi - _within_tolerance "read" $rbytes $expectedread 5% -v - _within_tolerance "write" $wbytes $expectedwrite 5% -v + _within_tolerance "read" $rbytes $expectedread $readtol -v + _within_tolerance "write" $wbytes $expectedwrite $writetol -v } # Move current process to another cgroup. @@ -113,7 +115,7 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" -c fsync \ $SCRATCH_MNT/file >> $seqres.full 2>&1 switch_cg $cgdir $XFS_IO_PROG -c fsync $SCRATCH_MNT/file -check_cg $cgdir/$seq-cg $iosize $iosize +check_cg $cgdir/$seq-cg $iosize $iosize 5% 5% # Write from one cgroup then read and write from a second. Writes are charged to # the first group and nothing to the second. @@ -126,8 +128,12 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" $SCRATCH_MNT/file \ >> $seqres.full 2>&1 switch_cg $cgdir $XFS_IO_PROG -c fsync $SCRATCH_MNT/file -check_cg $cgdir/$seq-cg 0 $iosize -check_cg $cgdir/$seq-cg-2 0 0 +# Use a fixed value tolerance for the expected value of zero here +# because filesystems might perform a small number of metadata reads to +# complete the write. On ext2/3 with 1k block size, the read bytes is +# as large as 33792. +check_cg $cgdir/$seq-cg 0 $iosize 33792 5% +check_cg $cgdir/$seq-cg-2 0 0 0 0 # Read from one cgroup, read & write from a second. Both reads and writes are # charged to the first group and nothing to the second. @@ -140,8 +146,8 @@ $XFS_IO_PROG -c "pread 0 $iosize" -c "pwrite 0 $iosize" $SCRATCH_MNT/file \ >> $seqres.full 2>&1 switch_cg $cgdir $XFS_IO_PROG -c fsync $SCRATCH_MNT/file -check_cg $cgdir/$seq-cg $iosize $iosize -check_cg $cgdir/$seq-cg-2 0 0 +check_cg $cgdir/$seq-cg $iosize $iosize 5% 5% +check_cg $cgdir/$seq-cg-2 0 0 0 0 echo "-io" > $cgdir/cgroup.subtree_control || _fail "subtree control"