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zfs: combine zio caches if possible

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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.
This commit is contained in:
Mateusz Guzik 2020-11-10 14:23:46 +00:00
parent 41ce62251c
commit 4426311a3c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=367569
1 changed files with 56 additions and 25 deletions
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81
sys/contrib/openzfs/module/zfs/zio.c
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@ -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;
n = SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT;
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
#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]);
}
zio_buf_cache[c] = NULL;
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]);
/*
* 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_data_buf_cache[c] = NULL;
kmem_cache_destroy(cache);
}
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;
}
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);