tests/zfs-tests/tests/functional/l2arc/l2arc_mfuonly_pos.ksh

   1 #!/bin/ksh -p
   2 #
   3 # CDDL HEADER START
   4 #
   5 # This file and its contents are supplied under the terms of the
   6 # Common Development and Distribution License ("CDDL"), version 1.0.
   7 # You may only use this file in accordance with the terms of version
   8 # 1.0 of the CDDL.
   9 #
  10 # A full copy of the text of the CDDL should have accompanied this
  11 # source.  A copy of the CDDL is also available via the Internet at
  12 # http://www.illumos.org/license/CDDL.
  13 #
  14 # CDDL HEADER END
  15 #
  16
  17 #
  18 # Copyright (c) 2020, George Amanakis. All rights reserved.
  19 #
  20
  21 . $STF_SUITE/include/libtest.shlib
  22 . $STF_SUITE/tests/functional/l2arc/l2arc.cfg
  23
  24 #
  25 # DESCRIPTION:
  26 #       l2arc_mfuonly does not cache MRU buffers
  27 #
  28 # STRATEGY:
  29 #       1. Set l2arc_mfuonly=yes
  30 #       2. Create pool with a cache device.
  31 #       3. Create a random file in that pool, smaller than the cache device
  32 #               and random read for 10 sec.
  33 #       4. Export and re-import the pool. This is necessary as some MFU ghost
  34 #               buffers with prefetch status may transition to MRU eventually.
  35 #               By re-importing the pool the l2 arcstats reflect the ARC state
  36 #               of L2ARC buffers upon their caching in L2ARC.
  37 #       5. Verify l2arc_mru_asize is 0.
  38 #
  39
  40 verify_runnable "global"
  41
  42 log_assert "l2arc_mfuonly does not cache MRU buffers."
  43
  44 function cleanup
  45 {
  46         if poolexists $TESTPOOL ; then
  47                 destroy_pool $TESTPOOL
  48         fi
  49
  50         log_must set_tunable32 L2ARC_NOPREFETCH $noprefetch
  51         log_must set_tunable32 L2ARC_MFUONLY $mfuonly
  52         log_must set_tunable32 PREFETCH_DISABLE $zfsprefetch
  53 }
  54 log_onexit cleanup
  55
  56 # L2ARC_NOPREFETCH is set to 1 as some prefetched buffers may
  57 # transition to MRU.
  58 typeset noprefetch=$(get_tunable L2ARC_NOPREFETCH)
  59 log_must set_tunable32 L2ARC_NOPREFETCH 1
  60
  61 typeset mfuonly=$(get_tunable L2ARC_MFUONLY)
  62 log_must set_tunable32 L2ARC_MFUONLY 1
  63
  64 typeset zfsprefetch=$(get_tunable PREFETCH_DISABLE)
  65 log_must set_tunable32 PREFETCH_DISABLE 1
  66
  67 typeset fill_mb=800
  68 typeset cache_sz=$(( 1.4 * $fill_mb ))
  69 export FILE_SIZE=$(( floor($fill_mb / $NUMJOBS) ))M
  70
  71 log_must truncate -s ${cache_sz}M $VDEV_CACHE
  72
  73 typeset log_blk_start=$(get_arcstat l2_log_blk_writes)
  74
  75 log_must zpool create -f $TESTPOOL $VDEV cache $VDEV_CACHE
  76
  77 log_must fio $FIO_SCRIPTS/mkfiles.fio
  78 log_must fio $FIO_SCRIPTS/random_reads.fio
  79
  80 log_must zpool export $TESTPOOL
  81 log_must zpool import -d $VDIR $TESTPOOL
  82
  83 # Regardless of l2arc_noprefetch, some MFU buffers might be evicted
  84 # from ARC, accessed later on as prefetches and transition to MRU as
  85 # prefetches.
  86 # If accessed again they are counted as MRU and the l2arc_mru_asize arcstat
  87 # will not be 0 (mentioned also in zfs.4)
  88 # For the purposes of this test we mitigate this by disabling (predictive)
  89 # ZFS prefetches with zfs_prefetch_disable=1.
  90 log_must test $(get_arcstat l2_mru_asize) -eq 0
  91
  92 log_must zpool destroy -f $TESTPOOL
  93
  94 log_pass "l2arc_mfuonly does not cache MRU buffers."