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Add bespoken metrics for kernel module cache misses

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This commit is contained in:
Heikki Linnakangas
2025-05-21 00:20:39 +03:00
parent 6ddcf68829
commit eaad1db9f0
1 changed files with 27 additions and 2 deletions
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29
pgxn/neon/file_cache.c
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@@ -164,6 +164,11 @@ typedef struct FileCacheControl
uint64 time_write; /* time spent writing (us) */
uint64 resizes; /* number of LFC resizes */
uint64 evicted_pages; /* number of evicted pages */
/* FIXME: should make these atomic, they're not protected by any locks */
uint64 kernel_module_read_misses; /* ENOENT returns from read ioctl */
uint64 kernel_module_write_misses; /* ENOMEM returns from write ioctl */
dlist_head lru; /* double linked list for LRU replacement
* algorithm */
dlist_head holes; /* double linked list of punched holes */
@@ -1440,7 +1445,12 @@ pread_with_ioctl(void *buffer, uint64 blkno)
.length = POSTGRES_PAGE_SIZE,
.buffer = (__u64)(uintptr_t) buffer
};
return ioctl(lfc_desc, NEON_IOCTL_READ, &args);
int rc;
rc = ioctl(lfc_desc, NEON_IOCTL_READ, &args);
if (rc < 0 && errno == ENOENT)
lfc_ctl->kernel_module_read_misses++;
return rc;
}
static int
@@ -1455,7 +1465,12 @@ pwrite_with_ioctl(const void *buffer, uint64 blkno)
.length = POSTGRES_PAGE_SIZE,
.buffer = (__u64)(uintptr_t) buffer
};
return ioctl(lfc_desc, NEON_IOCTL_WRITE, &args);
int rc;
rc = ioctl(lfc_desc, NEON_IOCTL_WRITE, &args);
if (rc < 0 && errno == ENOMEM)
lfc_ctl->kernel_module_write_misses++;
return rc;
}
/*
@@ -2101,6 +2116,16 @@ neon_get_lfc_stats(PG_FUNCTION_ARGS)
if (lfc_ctl)
value = lfc_ctl->pinned;
break;
case 10:
key = "file_cache_kernel_module_read_misses";
if (lfc_ctl)
value = lfc_ctl->kernel_module_read_misses;
break;
case 11:
key = "file_cache_kernel_module_write_misses";
if (lfc_ctl)
value = lfc_ctl->kernel_module_write_misses;
break;
default:
SRF_RETURN_DONE(funcctx);
}