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Add functions for reporting LFC hits and misses

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This commit is contained in:
Konstantin Knizhnik
2023-10-06 09:22:30 +03:00
parent 831f3a921e
commit f536dd830c
1 changed files with 23 additions and 0 deletions
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23
pgxn/neon/file_cache.c
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@@ -85,6 +85,8 @@ typedef struct FileCacheControl
uint32 size; /* size of cache file in chunks */
uint32 used; /* number of used chunks */
uint32 limit; /* shared copy of lfc_size_limit */
uint64 hits;
uint64 misses;
dlist_head lru; /* double linked list for LRU replacement algorithm */
} FileCacheControl;
@@ -208,6 +210,8 @@ lfc_shmem_startup(void)
lfc_ctl->generation = 0;
lfc_ctl->size = 0;
lfc_ctl->used = 0;
lfc_ctl->hits = 0;
lfc_ctl->misses = 0;
dlist_init(&lfc_ctl->lru);
/* Recreate file cache on restart */
@@ -590,6 +594,7 @@ lfc_read(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
if (entry == NULL || (entry->bitmap[chunk_offs >> 5] & (1 << (chunk_offs & 31))) == 0)
{
/* Page is not cached */
lfc_ctl->misses += 1; /* race condition here, but precise value is not needed */
LWLockRelease(lfc_lock);
return false;
}
@@ -614,6 +619,7 @@ lfc_read(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
if (lfc_ctl->generation == generation)
{
Assert(LFC_ENABLED());
lfc_ctl->hits += 1;
Assert(entry->access_count > 0);
if (--entry->access_count == 0)
dlist_push_tail(&lfc_ctl->lru, &entry->lru_node);
@@ -742,6 +748,23 @@ typedef struct
LocalCachePagesRec *record;
} LocalCachePagesContext;
PG_FUNCTION_INFO_V1(local_cache_hits);
Datum
local_cache_hits(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(lfc_ctl ? lfc_ctl->hits : -1);
}
PG_FUNCTION_INFO_V1(local_cache_misses);
Datum
local_cache_misses(PG_FUNCTION_ARGS)
{
PG_RETURN_INT64(lfc_ctl ? lfc_ctl->misses : -1);
}
/*
* Function returning data from the local file cache
* relation node/tablespace/database/blocknum and access_counter