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[PATCH 2/6] block/block-copy: limit copy_range_size to 16 MiB
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
[PATCH 2/6] block/block-copy: limit copy_range_size to 16 MiB |
Date: |
Thu, 3 Oct 2019 20:15:35 +0300 |
Large copy range may imply memory allocation and large io effort, so
using 2G copy range request may be bad idea. Let's limit it to 16 MiB.
It also helps the following patch to refactor copy-with-offload
fallback to copy-with-bounce-buffer.
Note, that total memory usage of backup is still not limited, it will
be fixed in further commit.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
block/block-copy.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/block/block-copy.c b/block/block-copy.c
index aca0f893d7..75287ce24d 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -18,6 +18,9 @@
#include "qapi/error.h"
#include "block/block-copy.h"
#include "sysemu/block-backend.h"
+#include "qemu/units.h"
+
+#define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
int64_t start,
@@ -70,9 +73,12 @@ BlockCopyState *block_copy_state_new(BdrvChild *source,
BdrvChild *target,
{
BlockCopyState *s;
BdrvDirtyBitmap *copy_bitmap;
+
+ /* Ignore BLOCK_COPY_MAX_COPY_RANGE if requested cluster_size is larger */
uint32_t max_transfer =
- MIN_NON_ZERO(INT_MAX, MIN_NON_ZERO(source->bs->bl.max_transfer,
- target->bs->bl.max_transfer));
+ MIN_NON_ZERO(MAX(cluster_size, BLOCK_COPY_MAX_COPY_RANGE),
+ MIN_NON_ZERO(source->bs->bl.max_transfer,
+ target->bs->bl.max_transfer));
copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
errp);
--
2.21.0
- [PATCH 0/6] block-copy: memory limit, Vladimir Sementsov-Ogievskiy, 2019/10/03
- [PATCH 2/6] block/block-copy: limit copy_range_size to 16 MiB,
Vladimir Sementsov-Ogievskiy <=
- [PATCH 5/6] block/block-copy: add memory limit, Vladimir Sementsov-Ogievskiy, 2019/10/03
- Re: [PATCH 5/6] block/block-copy: add memory limit, Max Reitz, 2019/10/07
- Re: [PATCH 5/6] block/block-copy: add memory limit, Vladimir Sementsov-Ogievskiy, 2019/10/07
- Re: [PATCH 5/6] block/block-copy: add memory limit, Max Reitz, 2019/10/08
- Re: [PATCH 5/6] block/block-copy: add memory limit, Vladimir Sementsov-Ogievskiy, 2019/10/08
- Re: [PATCH 5/6] block/block-copy: add memory limit, Vladimir Sementsov-Ogievskiy, 2019/10/08
- Re: [PATCH 5/6] block/block-copy: add memory limit, Max Reitz, 2019/10/08
- Re: [PATCH 5/6] block/block-copy: add memory limit, Max Reitz, 2019/10/08
[PATCH 4/6] util: introduce co-shared-amount, Vladimir Sementsov-Ogievskiy, 2019/10/03