xemu/tests/qemu-iotests/071.out
Evgeny Yakovlev 3ff2f67a7c block: ignore flush requests when storage is clean
Some guests (win2008 server for example) do a lot of unnecessary
flushing when underlying media has not changed. This adds additional
overhead on host when calling fsync/fdatasync.

This change introduces a write generation scheme in BlockDriverState.
Current write generation is checked against last flushed generation to
avoid unnessesary flushes.

The problem with excessive flushing was found by a performance test
which does parallel directory tree creation (from 2 processes).
Results improved from 0.424 loops/sec to 0.432 loops/sec.
Each loop creates 10^3 directories with 10 files in each.

This affected some blkdebug testcases that were expecting error logs from
failure-injected flushes which are now skipped entirely
(tests 026 071 089).

This also affects the performance of block jobs and thus BLOCK_JOB_READY
events for driver-mirror and active block-commit commands now arrives
faster, before QMP send successfully returns to caller (tests 141 144).

Signed-off-by: Evgeny Yakovlev <eyakovlev@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1468870792-7411-5-git-send-email-den@openvz.org
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <famz@redhat.com>
CC: John Snow <jsnow@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
2016-07-18 18:19:01 -04:00

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QA output created by 071
=== Testing blkverify through filename ===
Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
read 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 512/512 bytes at offset 229376
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 512/512 bytes at offset 229376
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
blkverify: read sector_num=0 nb_sectors=1 contents mismatch in sector 0
=== Testing blkverify through file blockref ===
Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
read 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 512/512 bytes at offset 229376
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 512/512 bytes at offset 229376
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
blkverify: read sector_num=0 nb_sectors=1 contents mismatch in sector 0
=== Testing blkdebug through filename ===
read failed: Input/output error
=== Testing blkdebug through file blockref ===
read failed: Input/output error
=== Testing blkdebug on existing block device ===
Testing:
QMP_VERSION
{"return": {}}
{"return": {}}
{"return": {}}
read failed: Input/output error
{"return": ""}
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN"}
=== Testing blkverify on existing block device ===
Testing:
QMP_VERSION
{"return": {}}
{"return": {}}
{"return": {}}
blkverify: read sector_num=0 nb_sectors=1 contents mismatch in sector 0
=== Testing blkverify on existing raw block device ===
Testing:
QMP_VERSION
{"return": {}}
{"return": {}}
{"return": {}}
blkverify: read sector_num=0 nb_sectors=1 contents mismatch in sector 0
=== Testing blkdebug's set-state through QMP ===
Testing:
QMP_VERSION
{"return": {}}
{"return": {}}
{"return": {}}
read 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
{"return": ""}
wrote 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
{"return": ""}
read failed: Input/output error
{"return": ""}
{"return": {}}
{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN"}
*** done