Author: mjg
Date: Tue Nov 10 14:23:46 2020
New Revision: 367569
URL: https://svnweb.freebsd.org/changeset/base/367569
Log:
zfs: combine zio caches if possible
This deduplicates 2 sets of caches using the same sizes.
Memory savings fluctuate a lot, one sample result is buildworld on zfs
saving ~180MB RAM in reduced page count associated with zio caches.
Modified:
head/sys/contrib/openzfs/module/zfs/zio.c
Modified: head/sys/contrib/openzfs/module/zfs/zio.c
==============================================================================
--- head/sys/contrib/openzfs/module/zfs/zio.c Tue Nov 10 14:21:23 2020
(r367568)
+++ head/sys/contrib/openzfs/module/zfs/zio.c Tue Nov 10 14:23:46 2020
(r367569)
@@ -204,6 +204,19 @@ zio_init(void)
if (align != 0) {
char name[36];
+ if (cflags == data_cflags) {
+ /*
+ * Resulting kmem caches would be identical.
+ * Save memory by creating only one.
+ */
+ (void) snprintf(name, sizeof (name),
+ "zio_buf_comb_%lu", (ulong_t)size);
+ zio_buf_cache[c] = kmem_cache_create(name,
+ size, align, NULL, NULL, NULL, NULL, NULL,
+ cflags);
+ zio_data_buf_cache[c] = zio_buf_cache[c];
+ continue;
+ }
(void) snprintf(name, sizeof (name), "zio_buf_%lu",
(ulong_t)size);
zio_buf_cache[c] = kmem_cache_create(name, size,
@@ -234,37 +247,55 @@ zio_init(void)
void
zio_fini(void)
{
- size_t c;
- kmem_cache_t *last_cache = NULL;
- kmem_cache_t *last_data_cache = NULL;
+ size_t i, j, n;
+ kmem_cache_t *cache;
- for (c = 0; c < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; c++) {
-#ifdef _ILP32
- /*
- * Cache size limited to 1M on 32-bit platforms until ARC
- * buffers no longer require virtual address space.
- */
- if (((c + 1) << SPA_MINBLOCKSHIFT) > zfs_max_recordsize)
- break;
-#endif
+ n = SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT;
+
#if defined(ZFS_DEBUG) && !defined(_KERNEL)
- if (zio_buf_cache_allocs[c] != zio_buf_cache_frees[c])
+ for (i = 0; i < n; i++) {
+ if (zio_buf_cache_allocs[i] != zio_buf_cache_frees[i])
(void) printf("zio_fini: [%d] %llu != %llu\n",
- (int)((c + 1) << SPA_MINBLOCKSHIFT),
- (long long unsigned)zio_buf_cache_allocs[c],
- (long long unsigned)zio_buf_cache_frees[c]);
+ (int)((i + 1) << SPA_MINBLOCKSHIFT),
+ (long long unsigned)zio_buf_cache_allocs[i],
+ (long long unsigned)zio_buf_cache_frees[i]);
+ }
#endif
- if (zio_buf_cache[c] != last_cache) {
- last_cache = zio_buf_cache[c];
- kmem_cache_destroy(zio_buf_cache[c]);
+
+ /*
+ * The same kmem cache can show up multiple times in both zio_buf_cache
+ * and zio_data_buf_cache. Do a wasteful but trivially correct scan to
+ * sort it out.
+ */
+ for (i = 0; i < n; i++) {
+ cache = zio_buf_cache[i];
+ if (cache == NULL)
+ continue;
+ for (j = i; j < n; j++) {
+ if (cache == zio_buf_cache[j])
+ zio_buf_cache[j] = NULL;
+ if (cache == zio_data_buf_cache[j])
+ zio_data_buf_cache[j] = NULL;
}
- zio_buf_cache[c] = NULL;
+ kmem_cache_destroy(cache);
+ }
- if (zio_data_buf_cache[c] != last_data_cache) {
- last_data_cache = zio_data_buf_cache[c];
- kmem_cache_destroy(zio_data_buf_cache[c]);
+ for (i = 0; i < n; i++) {
+ cache = zio_data_buf_cache[i];
+ if (cache == NULL)
+ continue;
+ for (j = i; j < n; j++) {
+ if (cache == zio_data_buf_cache[j])
+ zio_data_buf_cache[j] = NULL;
}
- zio_data_buf_cache[c] = NULL;
+ kmem_cache_destroy(cache);
+ }
+
+ for (i = 0; i < n; i++) {
+ if (zio_buf_cache[i] != NULL)
+ panic("zio_fini: zio_buf_cache[%d] != NULL", (int)i);
+ if (zio_data_buf_cache[i] != NULL)
+ panic("zio_fini: zio_data_buf_cache[%d] != NULL",
(int)i);
}
kmem_cache_destroy(zio_link_cache);
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