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cache: use same alg for cache size calc

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Use the same algorithm for cache metadata size as the cache tool is using.
This commit is contained in:
Zdenek Kabelac 2014-10-06 12:22:03 +02:00
parent d46c2f1c94
commit f76f2ce1df
1 changed files with 17 additions and 9 deletions
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26
lib/metadata/cache_manip.c
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@ -22,6 +22,12 @@
#include "activate.h"
#include "defaults.h"
/* https://github.com/jthornber/thin-provisioning-tools/blob/master/caching/cache_metadata_size.cc */
#define DM_TRANSACTION_OVERHEAD 4096 /* KiB */
#define DM_BYTES_PER_BLOCK 16 /* bytes */
#define DM_HINT_OVERHEAD_PER_BLOCK 8 /* bytes */
#define DM_MAX_HINT_WIDTH (4+16) /* bytes, TODO: configurable ?? */
const char *get_cachepool_cachemode_name(const struct lv_segment *seg)
{
if (seg->feature_flags & DM_CACHE_FEATURE_WRITEBACK)
@ -39,6 +45,7 @@ int update_cache_pool_params(struct volume_group *vg, unsigned attr,
int *chunk_size_calc_method, uint32_t *chunk_size)
{
uint64_t min_meta_size;
uint32_t extent_size = vg->extent_size;
if (!(passed_args & PASS_ARG_CHUNK_SIZE))
*chunk_size = DEFAULT_CACHE_POOL_CHUNK_SIZE * 2;
@ -59,15 +66,16 @@ int update_cache_pool_params(struct volume_group *vg, unsigned attr,
/*
* Default meta size is:
* (4MiB + (16 Bytes for each chunk-sized block))
* ... plus a good amount of padding (2x) to cover any
* policy hint data that may be added in the future.
* (Overhead + mapping size + hint size)
*/
min_meta_size = (uint64_t)data_extents * vg->extent_size * 16;
min_meta_size /= *chunk_size; /* # of Bytes we need */
min_meta_size *= 2; /* plus some padding */
min_meta_size /= 512; /* in sectors */
min_meta_size += 4*1024*2; /* plus 4MiB */
min_meta_size = (uint64_t) data_extents * extent_size / *chunk_size; /* nr_chunks */
min_meta_size *= (DM_BYTES_PER_BLOCK + DM_MAX_HINT_WIDTH + DM_HINT_OVERHEAD_PER_BLOCK);
min_meta_size = (min_meta_size + (SECTOR_SIZE - 1)) >> SECTOR_SHIFT; /* in sectors */
min_meta_size += DM_TRANSACTION_OVERHEAD * (1024 >> SECTOR_SHIFT);
/* Round up to extent size */
if (min_meta_size % extent_size)
min_meta_size += extent_size - min_meta_size % extent_size;
if (!*pool_metadata_size)
*pool_metadata_size = min_meta_size;
@ -79,7 +87,7 @@ int update_cache_pool_params(struct volume_group *vg, unsigned attr,
display_size(vg->cmd, *pool_metadata_size));
} else if (*pool_metadata_size < min_meta_size) {
if (passed_args & PASS_ARG_POOL_METADATA_SIZE)
log_warn("WARNING: Minimum supported pool metadata size is %s "
log_warn("WARNING: Minimum required pool metadata size is %s "
"(needs extra %s).",
display_size(vg->cmd, min_meta_size),
display_size(vg->cmd, min_meta_size - *pool_metadata_size));