This patch adds support for the per-CPU acomp_ctx to track multiple
compression/decompression requests. The zswap_cpu_comp_prepare() cpu
onlining code will check if the compressor supports batching. If so, it
will allocate the necessary batching resources.
However, zswap does not use more than one request yet. Follow-up patches
will actually utilize the multiple acomp_ctx requests/buffers for batch
compression/decompression of multiple pages.
The newly added ZSWAP_MAX_BATCH_SIZE limits the amount of extra memory used
for batching. There is no extra memory usage for compressors that do not
support batching.
Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
---
mm/zswap.c | 132 +++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 98 insertions(+), 34 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index a2baceed3bf9..dc7d1ff04b22 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -78,6 +78,16 @@ static bool zswap_pool_reached_full;
#define ZSWAP_PARAM_UNSET ""
+/*
+ * For compression batching of large folios:
+ * Maximum number of acomp compress requests that will be processed
+ * in a batch, iff the zswap compressor supports batching.
+ * This limit exists because we preallocate enough requests and buffers
+ * in the per-cpu acomp_ctx accordingly. Hence, a higher limit means higher
+ * memory usage.
+ */
+#define ZSWAP_MAX_BATCH_SIZE 8U
+
static int zswap_setup(void);
/* Enable/disable zswap */
@@ -143,9 +153,10 @@ bool zswap_never_enabled(void)
struct crypto_acomp_ctx {
struct crypto_acomp *acomp;
- struct acomp_req *req;
+ struct acomp_req **reqs;
+ u8 **buffers;
+ unsigned int nr_reqs;
struct crypto_wait wait;
- u8 *buffer;
struct mutex mutex;
bool is_sleepable;
};
@@ -821,15 +832,13 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
struct crypto_acomp *acomp = NULL;
- struct acomp_req *req = NULL;
- u8 *buffer = NULL;
- int ret;
+ unsigned int nr_reqs = 1;
+ int ret = -ENOMEM;
+ int i;
- buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
- if (!buffer) {
- ret = -ENOMEM;
- goto fail;
- }
+ acomp_ctx->buffers = NULL;
+ acomp_ctx->reqs = NULL;
+ acomp_ctx->nr_reqs = 0;
acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
if (IS_ERR(acomp)) {
@@ -839,12 +848,30 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
goto fail;
}
- req = acomp_request_alloc(acomp);
- if (!req) {
- pr_err("could not alloc crypto acomp_request %s\n",
- pool->tfm_name);
- ret = -ENOMEM;
+ if (acomp_has_async_batching(acomp))
+ nr_reqs = min(ZSWAP_MAX_BATCH_SIZE, crypto_acomp_batch_size(acomp));
+
+ acomp_ctx->buffers = kcalloc_node(nr_reqs, sizeof(u8 *), GFP_KERNEL, cpu_to_node(cpu));
+ if (!acomp_ctx->buffers)
+ goto fail;
+
+ for (i = 0; i < nr_reqs; ++i) {
+ acomp_ctx->buffers[i] = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+ if (!acomp_ctx->buffers[i])
+ goto fail;
+ }
+
+ acomp_ctx->reqs = kcalloc_node(nr_reqs, sizeof(struct acomp_req *), GFP_KERNEL, cpu_to_node(cpu));
+ if (!acomp_ctx->reqs)
goto fail;
+
+ for (i = 0; i < nr_reqs; ++i) {
+ acomp_ctx->reqs[i] = acomp_request_alloc(acomp);
+ if (!acomp_ctx->reqs[i]) {
+ pr_err("could not alloc crypto acomp_request reqs[%d] %s\n",
+ i, pool->tfm_name);
+ goto fail;
+ }
}
/*
@@ -853,6 +880,13 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
* again resulting in a deadlock.
*/
mutex_lock(&acomp_ctx->mutex);
+
+ /*
+ * The crypto_wait is used only in fully synchronous, i.e., with scomp
+ * or non-poll mode of acomp, hence there is only one "wait" per
+ * acomp_ctx, with callback set to reqs[0], under the assumption that
+ * there is at least 1 request per acomp_ctx.
+ */
crypto_init_wait(&acomp_ctx->wait);
/*
@@ -860,20 +894,33 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
* crypto_wait_req(); if the backend of acomp is scomp, the callback
* won't be called, crypto_wait_req() will return without blocking.
*/
- acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+ acomp_request_set_callback(acomp_ctx->reqs[0], CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_req_done, &acomp_ctx->wait);
- acomp_ctx->buffer = buffer;
+ acomp_ctx->nr_reqs = nr_reqs;
acomp_ctx->acomp = acomp;
acomp_ctx->is_sleepable = acomp_is_async(acomp);
- acomp_ctx->req = req;
mutex_unlock(&acomp_ctx->mutex);
return 0;
fail:
+ if (acomp_ctx->buffers) {
+ for (i = 0; i < nr_reqs; ++i)
+ kfree(acomp_ctx->buffers[i]);
+ kfree(acomp_ctx->buffers);
+ acomp_ctx->buffers = NULL;
+ }
+
+ if (acomp_ctx->reqs) {
+ for (i = 0; i < nr_reqs; ++i)
+ if (!IS_ERR_OR_NULL(acomp_ctx->reqs[i]))
+ acomp_request_free(acomp_ctx->reqs[i]);
+ kfree(acomp_ctx->reqs);
+ acomp_ctx->reqs = NULL;
+ }
+
if (acomp)
crypto_free_acomp(acomp);
- kfree(buffer);
return ret;
}
@@ -883,14 +930,31 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
mutex_lock(&acomp_ctx->mutex);
+
if (!IS_ERR_OR_NULL(acomp_ctx)) {
- if (!IS_ERR_OR_NULL(acomp_ctx->req))
- acomp_request_free(acomp_ctx->req);
- acomp_ctx->req = NULL;
+ int i;
+
+ if (acomp_ctx->reqs) {
+ for (i = 0; i < acomp_ctx->nr_reqs; ++i)
+ if (!IS_ERR_OR_NULL(acomp_ctx->reqs[i]))
+ acomp_request_free(acomp_ctx->reqs[i]);
+ kfree(acomp_ctx->reqs);
+ acomp_ctx->reqs = NULL;
+ }
+
+ if (acomp_ctx->buffers) {
+ for (i = 0; i < acomp_ctx->nr_reqs; ++i)
+ kfree(acomp_ctx->buffers[i]);
+ kfree(acomp_ctx->buffers);
+ acomp_ctx->buffers = NULL;
+ }
+
if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
crypto_free_acomp(acomp_ctx->acomp);
- kfree(acomp_ctx->buffer);
+
+ acomp_ctx->nr_reqs = 0;
}
+
mutex_unlock(&acomp_ctx->mutex);
return 0;
@@ -903,7 +967,7 @@ static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool)
for (;;) {
acomp_ctx = raw_cpu_ptr(pool->acomp_ctx);
mutex_lock(&acomp_ctx->mutex);
- if (likely(acomp_ctx->req))
+ if (likely(acomp_ctx->reqs))
return acomp_ctx;
/*
* It is possible that we were migrated to a different CPU after
@@ -935,7 +999,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
u8 *dst;
acomp_ctx = acomp_ctx_get_cpu_lock(pool);
- dst = acomp_ctx->buffer;
+ dst = acomp_ctx->buffers[0];
sg_init_table(&input, 1);
sg_set_page(&input, page, PAGE_SIZE, 0);
@@ -945,7 +1009,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
* giving the dst buffer with enough length to avoid buffer overflow.
*/
sg_init_one(&output, dst, PAGE_SIZE * 2);
- acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
+ acomp_request_set_params(acomp_ctx->reqs[0], &input, &output, PAGE_SIZE, dlen);
/*
* it maybe looks a little bit silly that we send an asynchronous request,
@@ -959,8 +1023,8 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry,
* but in different threads running on different cpu, we have different
* acomp instance, so multiple threads can do (de)compression in parallel.
*/
- comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
- dlen = acomp_ctx->req->dlen;
+ comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->reqs[0]), &acomp_ctx->wait);
+ dlen = acomp_ctx->reqs[0]->dlen;
if (comp_ret)
goto unlock;
@@ -1011,19 +1075,19 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
*/
if ((acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) ||
!virt_addr_valid(src)) {
- memcpy(acomp_ctx->buffer, src, entry->length);
- src = acomp_ctx->buffer;
+ memcpy(acomp_ctx->buffers[0], src, entry->length);
+ src = acomp_ctx->buffers[0];
zpool_unmap_handle(zpool, entry->handle);
}
sg_init_one(&input, src, entry->length);
sg_init_table(&output, 1);
sg_set_folio(&output, folio, PAGE_SIZE, 0);
- acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE);
- BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait));
- BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
+ acomp_request_set_params(acomp_ctx->reqs[0], &input, &output, entry->length, PAGE_SIZE);
+ BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->reqs[0]), &acomp_ctx->wait));
+ BUG_ON(acomp_ctx->reqs[0]->dlen != PAGE_SIZE);
- if (src != acomp_ctx->buffer)
+ if (src != acomp_ctx->buffers[0])
zpool_unmap_handle(zpool, entry->handle);
acomp_ctx_put_unlock(acomp_ctx);
}
--
2.27.0
