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[Qemu-devel] [PATCH v3 2/5] qcow2: record fragmentation statistics durin
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v3 2/5] qcow2: record fragmentation statistics during check |
Date: |
Thu, 7 Feb 2013 17:15:02 +0100 |
The qemu-img check command can display fragmentation statistics:
* Total number of clusters in virtual disk
* Number of allocated clusters
* Number of fragmented clusters
This patch adds fragmentation statistics support to qcow2.
Compressed and normal clusters count as allocated. Zero clusters are
not counted as allocated unless their L2 entry has a non-zero offset
(e.g. preallocation).
Only the current L1 table counts towards the statistics - snapshots are
ignored.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2-refcount.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 4eec4b1..771b7b2 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -917,6 +917,7 @@ static void inc_refcounts(BlockDriverState *bs,
/* Flags for check_refcounts_l1() and check_refcounts_l2() */
enum {
CHECK_OFLAG_COPIED = 0x1, /* check QCOW_OFLAG_COPIED matches refcount */
+ CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */
};
/*
@@ -933,6 +934,7 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
{
BDRVQcowState *s = bs->opaque;
uint64_t *l2_table, l2_entry;
+ uint64_t next_contiguous_offset = 0;
int i, l2_size, nb_csectors, refcount;
/* Read L2 table from disk */
@@ -963,6 +965,17 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
l2_entry &= s->cluster_offset_mask;
inc_refcounts(bs, res, refcount_table, refcount_table_size,
l2_entry & ~511, nb_csectors * 512);
+
+ if (flags & CHECK_FRAG_INFO) {
+ res->bfi.allocated_clusters++;
+
+ /* Compressed clusters are fragmented by nature. Since they
+ * take up sub-sector space but we only have sector granularity
+ * I/O we need to re-read the same sectors even for adjacent
+ * compressed clusters.
+ */
+ res->bfi.fragmented_clusters++;
+ }
break;
case QCOW2_CLUSTER_ZERO:
@@ -990,6 +1003,15 @@ static int check_refcounts_l2(BlockDriverState *bs,
BdrvCheckResult *res,
}
}
+ if (flags & CHECK_FRAG_INFO) {
+ res->bfi.allocated_clusters++;
+ if (next_contiguous_offset &&
+ offset != next_contiguous_offset) {
+ res->bfi.fragmented_clusters++;
+ }
+ next_contiguous_offset = offset + s->cluster_size;
+ }
+
/* Mark cluster as used */
inc_refcounts(bs, res, refcount_table,refcount_table_size,
offset, s->cluster_size);
@@ -1125,6 +1147,7 @@ int qcow2_check_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
size = bdrv_getlength(bs->file);
nb_clusters = size_to_clusters(s, size);
+ res->bfi.total_clusters = nb_clusters;
refcount_table = g_malloc0(nb_clusters * sizeof(uint16_t));
/* header */
@@ -1134,7 +1157,7 @@ int qcow2_check_refcounts(BlockDriverState *bs,
BdrvCheckResult *res,
/* current L1 table */
ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
s->l1_table_offset, s->l1_size,
- CHECK_OFLAG_COPIED);
+ CHECK_OFLAG_COPIED | CHECK_FRAG_INFO);
if (ret < 0) {
goto fail;
}
--
1.8.1
- [Qemu-devel] [PATCH v3 0/5] qcow2: add fragmentation and compression info support, Stefan Hajnoczi, 2013/02/07
- [Qemu-devel] [PATCH v3 5/5] qcow2: support compressed clusters in BlockFragInfo, Stefan Hajnoczi, 2013/02/07
- [Qemu-devel] [PATCH v3 3/5] qemu-img: fix missing space in qemu-img check output, Stefan Hajnoczi, 2013/02/07
- [Qemu-devel] [PATCH v3 1/5] qcow2: introduce check_refcounts_l1/l2() flags, Stefan Hajnoczi, 2013/02/07
- [Qemu-devel] [PATCH v3 4/5] qemu-img: add compressed clusters to BlockFragInfo, Stefan Hajnoczi, 2013/02/07
- [Qemu-devel] [PATCH v3 2/5] qcow2: record fragmentation statistics during check,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH v3 0/5] qcow2: add fragmentation and compression info support, Eric Blake, 2013/02/07
- Re: [Qemu-devel] [PATCH v3 0/5] qcow2: add fragmentation and compression info support, Kevin Wolf, 2013/02/12
- Re: [Qemu-devel] [PATCH v3 0/5] qcow2: add fragmentation and compression info support, Stefan Hajnoczi, 2013/02/12