139 lines
4.6 KiB
Diff
139 lines
4.6 KiB
Diff
From 83e1167e1a350bd08ac6245f47a5877438408492 Mon Sep 17 00:00:00 2001
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From: "Richard W.M. Jones" <rjones@redhat.com>
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Date: Mon, 26 Jul 2021 17:39:23 +0100
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Subject: [PATCH] cache, cow: Use a 64K block size by default
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Based on the results presented in the previous commit, use a 64K block
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size by default in both the cache and cow filters. For the cache
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filter you could go back to a 4K block size if you wanted by using the
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cache-min-block-size=4K parameter. For cow it is compiled in so
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cannot be adjusted.
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(cherry picked from commit c1905b0a28677d961babdb16d6f30ae61042c825)
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---
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filters/cache/cache.c | 2 +-
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filters/cache/nbdkit-cache-filter.pod | 4 ++--
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filters/cow/blk.h | 2 +-
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tests/test-cache-block-size.sh | 2 +-
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tests/test-cow-extents1.sh | 33 +++++++++++++++------------
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5 files changed, 23 insertions(+), 20 deletions(-)
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diff --git a/filters/cache/cache.c b/filters/cache/cache.c
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index 109ac89e..c912c5fb 100644
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--- a/filters/cache/cache.c
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+++ b/filters/cache/cache.c
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@@ -73,7 +73,7 @@
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static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
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unsigned blksize; /* actual block size (picked by blk.c) */
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-unsigned min_block_size = 4096;
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+unsigned min_block_size = 65536;
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enum cache_mode cache_mode = CACHE_MODE_WRITEBACK;
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int64_t max_size = -1;
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unsigned hi_thresh = 95, lo_thresh = 80;
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diff --git a/filters/cache/nbdkit-cache-filter.pod b/filters/cache/nbdkit-cache-filter.pod
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index 6cbd1c08..df9c1f99 100644
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--- a/filters/cache/nbdkit-cache-filter.pod
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+++ b/filters/cache/nbdkit-cache-filter.pod
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@@ -65,8 +65,8 @@ or can cheaply reconstruct.
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Set the minimum block size used by the cache. This must be a power of
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2 and E<ge> 4096.
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-The default is 4096, or the block size of the filesystem which
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-contains the temporary file storing the cache (whichever is larger).
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+The default is 64K, or the block size of the filesystem which contains
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+the temporary file storing the cache (whichever is larger).
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=item B<cache-max-size=>SIZE
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diff --git a/filters/cow/blk.h b/filters/cow/blk.h
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index b066c602..1bc85283 100644
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--- a/filters/cow/blk.h
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+++ b/filters/cow/blk.h
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@@ -36,7 +36,7 @@
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/* Size of a block in the overlay. A 4K block size means that we need
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* 64 MB of memory to store the bitmap for a 1 TB underlying image.
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*/
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-#define BLKSIZE 4096
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+#define BLKSIZE 65536
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/* Initialize the overlay and bitmap. */
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extern int blk_init (void);
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diff --git a/tests/test-cache-block-size.sh b/tests/test-cache-block-size.sh
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index a2a27407..d20cc940 100755
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--- a/tests/test-cache-block-size.sh
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+++ b/tests/test-cache-block-size.sh
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@@ -47,7 +47,7 @@ truncate -s 128K cache-block-size.img
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# Run nbdkit with the caching filter.
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start_nbdkit -P cache-block-size.pid -U $sock --filter=cache \
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- file cache-block-size.img cache-min-block-size=64K
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+ file cache-block-size.img cache-min-block-size=4K
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nbdsh --connect "nbd+unix://?socket=$sock" \
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-c '
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diff --git a/tests/test-cow-extents1.sh b/tests/test-cow-extents1.sh
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index 8e0e0383..ebfd83f6 100755
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--- a/tests/test-cow-extents1.sh
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+++ b/tests/test-cow-extents1.sh
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@@ -65,7 +65,7 @@ cleanup_fn rm -f $files
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# Create a base file which is half allocated, half sparse.
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dd if=/dev/urandom of=$base count=128 bs=1K
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-truncate -s 256K $base
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+truncate -s 4M $base
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lastmod="$(stat -c "%y" $base)"
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# Run nbdkit with a COW overlay.
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@@ -76,30 +76,33 @@ uri="nbd+unix:///?socket=$sock"
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nbdinfo --map "$uri" > $out
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cat $out
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if [ "$(tr -s ' ' < $out | cut -d' ' -f 1-4)" != " 0 131072 0
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- 131072 131072 3" ]; then
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+ 131072 4063232 3" ]; then
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echo "$0: unexpected initial file map"
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exit 1
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fi
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# Punch some holes.
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nbdsh -u "$uri" \
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- -c 'h.trim(4096, 4096)' \
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- -c 'h.trim(4098, 16383)' \
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- -c 'h.pwrite(b"1"*4096, 65536)' \
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- -c 'h.trim(8192, 131072)' \
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- -c 'h.pwrite(b"2"*8192, 196608)'
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+ -c 'bs = 65536' \
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+ -c 'h.trim(bs, bs)' \
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+ -c 'h.trim(bs+2, 4*bs-1)' \
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+ -c 'h.pwrite(b"1"*bs, 16*bs)' \
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+ -c 'h.trim(2*bs, 32*bs)' \
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+ -c 'h.pwrite(b"2"*(2*bs), 48*bs)'
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# The extents map should be fully allocated.
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nbdinfo --map "$uri" > $out
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cat $out
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-if [ "$(tr -s ' ' < $out | cut -d' ' -f 1-4)" != " 0 4096 0
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- 4096 4096 3
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- 8192 8192 0
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- 16384 4096 3
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- 20480 110592 0
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- 131072 65536 3
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- 196608 8192 0
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- 204800 57344 3" ]; then
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+if [ "$(tr -s ' ' < $out | cut -d' ' -f 1-4)" != " 0 65536 0
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+ 65536 131072 3
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+ 196608 65536 0
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+ 262144 65536 3
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+ 327680 65536 0
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+ 393216 655360 3
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+ 1048576 65536 0
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+ 1114112 2031616 3
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+ 3145728 131072 0
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+ 3276800 917504 3" ]; then
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echo "$0: unexpected trimmed file map"
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exit 1
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fi
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--
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2.31.1
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