3ff2f67a7c
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>
60 lines
2.9 KiB
Plaintext
60 lines
2.9 KiB
Plaintext
QA output created by 141
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Formatting 'TEST_DIR/b.IMGFMT', fmt=IMGFMT size=1048576
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Formatting 'TEST_DIR/m.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/b.IMGFMT
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/m.IMGFMT
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{"return": {}}
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=== Testing drive-backup ===
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{"return": {}}
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Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
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{"return": {}}
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{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: backup"}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_CANCELLED", "data": {"device": "drv0", "len": 1048576, "offset": 0, "speed": 0, "type": "backup"}}
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{"return": {}}
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=== Testing drive-mirror ===
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{"return": {}}
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Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "drv0", "len": 0, "offset": 0, "speed": 0, "type": "mirror"}}
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{"return": {}}
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{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: mirror"}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "drv0", "len": 0, "offset": 0, "speed": 0, "type": "mirror"}}
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{"return": {}}
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=== Testing active block-commit ===
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "drv0", "len": 0, "offset": 0, "speed": 0, "type": "commit"}}
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{"return": {}}
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{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: commit"}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "drv0", "len": 0, "offset": 0, "speed": 0, "type": "commit"}}
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{"return": {}}
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=== Testing non-active block-commit ===
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wrote 1048576/1048576 bytes at offset 0
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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{"return": {}}
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{"return": {}}
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{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: commit"}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_CANCELLED", "data": {"device": "drv0", "len": 1048576, "offset": 524288, "speed": 1, "type": "commit"}}
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{"return": {}}
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=== Testing block-stream ===
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wrote 1048576/1048576 bytes at offset 0
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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{"return": {}}
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{"return": {}}
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{"error": {"class": "GenericError", "desc": "Node 'drv0' is busy: block device is in use by block job: stream"}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_JOB_CANCELLED", "data": {"device": "drv0", "len": 1048576, "offset": 524288, "speed": 1, "type": "stream"}}
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{"return": {}}
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*** done
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