From fbaa6bb3d3b4be71b7e234e908cb3c6bd280a222 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Sat, 6 May 2017 19:05:50 -0500 Subject: qcow2: Optimize write zero of unaligned tail cluster We've already improved discards to operate efficiently on the tail of an unaligned qcow2 image; it's time to make a similar improvement to write zeroes. The special case is only valid at the tail cluster of a file, where we must recognize that any sectors beyond the image end would implicitly read as zero, and therefore should not penalize our logic for widening a partial cluster into writing the whole cluster as zero. However, note that for now, the special case of end-of-file is only recognized if there is no backing file, or if the backing file has the same length; that's because when the backing file is shorter than the active layer, we don't have code in place to recognize that reads of a sector unallocated at the top and beyond the backing end-of-file are implicitly zero. It's not much of a real loss, because most people don't use images that aren't cluster-aligned, or where the active layer is a different size than the backing layer (especially where the difference falls within a single cluster). Update test 154 to cover the new scenarios, using two images of intentionally differing length. While at it, fix the test to gracefully skip when run as ./check -qcow2 -o compat=0.10 154 since the older format lacks zero clusters already required earlier in the test. Signed-off-by: Eric Blake Reviewed-by: Max Reitz Message-id: 20170507000552.20847-11-eblake@redhat.com Signed-off-by: Max Reitz --- tests/qemu-iotests/154 | 160 ++++++++++++++++++++++++++++++++++++++++++++- tests/qemu-iotests/154.out | 128 ++++++++++++++++++++++++++++++++++++ 2 files changed, 286 insertions(+), 2 deletions(-) (limited to 'tests') diff --git a/tests/qemu-iotests/154 b/tests/qemu-iotests/154 index 7ca7219f08..dd8a426dad 100755 --- a/tests/qemu-iotests/154 +++ b/tests/qemu-iotests/154 @@ -2,7 +2,7 @@ # # qcow2 specific bdrv_pwrite_zeroes tests with backing files (complements 034) # -# Copyright (C) 2016 Red Hat, Inc. +# Copyright (C) 2016-2017 Red Hat, Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by @@ -42,7 +42,10 @@ _supported_proto file _supported_os Linux CLUSTER_SIZE=4k -size=128M +size=$((128 * 1024 * 1024)) + +# This test requires zero clusters, added in v3 images +_unsupported_imgopts compat=0.10 echo echo == backing file contains zeros == @@ -299,6 +302,159 @@ $QEMU_IO -c "read -P 0 75k 1k" "$TEST_IMG" | _filter_qemu_io $QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map +echo +echo == unaligned image tail cluster, no allocation needed == + +# With no backing file, write to all or part of unallocated partial cluster +# will mark the cluster as zero, but does not allocate. +# Re-create the image each time to get back to unallocated clusters. + +# Write at the front: sector-wise, the request is: 128m... | 00 -- -- -- +_make_test_img $((size + 2048)) +$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at the back: sector-wise, the request is: 128m... | -- -- -- 00 +_make_test_img $((size + 2048)) +$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at middle: sector-wise, the request is: 128m... | -- 00 00 -- +_make_test_img $((size + 2048)) +$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write entire cluster: sector-wise, the request is: 128m... | 00 00 00 00 +_make_test_img $((size + 2048)) +$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Repeat with backing file holding unallocated cluster. +# TODO: Note that this forces an allocation, because we aren't yet able to +# quickly detect that reads beyond EOF of the backing file are always zero +CLUSTER_SIZE=2048 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024)) + +# Write at the front: sector-wise, the request is: +# backing: 128m... | -- -- +# active: 128m... | 00 -- -- -- +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at the back: sector-wise, the request is: +# backing: 128m... | -- -- +# active: 128m... | -- -- -- 00 +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at middle: sector-wise, the request is: +# backing: 128m... | -- -- +# active: 128m... | -- 00 00 -- +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write entire cluster: sector-wise, the request is: +# backing: 128m... | -- -- +# active: 128m... | 00 00 00 00 +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Repeat with backing file holding zero'd cluster +# TODO: Note that this forces an allocation, because we aren't yet able to +# quickly detect that reads beyond EOF of the backing file are always zero +$QEMU_IO -c "write -z $size 512" "$TEST_IMG.base" | _filter_qemu_io + +# Write at the front: sector-wise, the request is: +# backing: 128m... | 00 00 +# active: 128m... | 00 -- -- -- +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at the back: sector-wise, the request is: +# backing: 128m... | 00 00 +# active: 128m... | -- -- -- 00 +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write at middle: sector-wise, the request is: +# backing: 128m... | 00 00 +# active: 128m... | -- 00 00 -- +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Write entire cluster: sector-wise, the request is: +# backing: 128m... | 00 00 +# active: 128m... | 00 00 00 00 +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# A preallocated cluster maintains its allocation, whether it stays as +# data due to a partial write: +# Convert 128m... | XX XX => ... | XX 00 +_make_test_img $((size + 1024)) +$QEMU_IO -c "write -P 1 $((size)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "write -z $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# or because it is the entire cluster and can use the zero flag: +# Convert 128m... | XX XX => ... | 00 00 +$QEMU_IO -c "write -z $((size)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $size 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +echo +echo == unaligned image tail cluster, allocation required == + +# Write beyond backing file must COW +# Backing file: 128m... | XX -- +# Active layer: 128m... | -- -- 00 -- +CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024)) +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -P 1 $((size)) 512" "$TEST_IMG.base" | _filter_qemu_io +$QEMU_IO -c "write -z $((size + 1024)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size + 512)) 1536" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + +# Writes at boundaries of (partial) cluster must not lose mid-cluster data +# Backing file: 128m: ... | -- XX +# Active layer: 128m: ... | 00 -- -- 00 +CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024)) +_make_test_img -b "$TEST_IMG.base" $((size + 2048)) +$QEMU_IO -c "write -P 1 $((size + 512)) 512" "$TEST_IMG.base" | _filter_qemu_io +$QEMU_IO -c "write -z $((size)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io +$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io +$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/154.out b/tests/qemu-iotests/154.out index d3b68e7729..d8485eeff2 100644 --- a/tests/qemu-iotests/154.out +++ b/tests/qemu-iotests/154.out @@ -282,4 +282,132 @@ read 1024/1024 bytes at offset 76800 { "start": 69632, "length": 4096, "depth": 0, "zero": true, "data": false}, { "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET}, { "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}] + +== unaligned image tail cluster, no allocation needed == +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 +wrote 512/512 bytes at offset 134219264 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 +wrote 1024/1024 bytes at offset 134218240 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 +wrote 2048/2048 bytes at offset 134217728 +2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}] +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752 +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134219264 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 1024/1024 bytes at offset 134218240 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 2048/2048 bytes at offset 134217728 +2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}] +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134219264 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 1024/1024 bytes at offset 134218240 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 2048/2048 bytes at offset 134217728 +2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +2048/2048 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}] +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134218752 +wrote 1024/1024 bytes at offset 134217728 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +wrote 512/512 bytes at offset 134218240 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134218240 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +1024/1024 bytes allocated at offset 128 MiB +[{ "start": 0, "length": 134217728, "depth": 0, "zero": true, "data": false}, +{ "start": 134217728, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +wrote 1024/1024 bytes at offset 134217728 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +1024/1024 bytes allocated at offset 128 MiB +read 1024/1024 bytes at offset 134217728 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +[{ "start": 0, "length": 134217728, "depth": 0, "zero": true, "data": false}, +{ "start": 134217728, "length": 1024, "depth": 0, "zero": true, "data": false, "offset": OFFSET}] + +== unaligned image tail cluster, allocation required == +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752 +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +wrote 512/512 bytes at offset 134218752 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 1536/1536 bytes at offset 134218240 +1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752 +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base +wrote 512/512 bytes at offset 134218240 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +wrote 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134218240 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 1024/1024 bytes at offset 134218752 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +wrote 512/512 bytes at offset 134219264 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134217728 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 512/512 bytes at offset 134218240 +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 1024/1024 bytes at offset 134218752 +1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false}, +{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}] *** done -- cgit v1.2.1