[PATCH 2/3] mm/zswap: remove the memcpy if acomp is not asynchronous

Barry Song
2024-01-03T09:50:40Z

From: Barry Song <v-songbaohua@oppo.com>

Most compressors are actually CPU-based and won't sleep during
compression and decompression. We should remove the redundant
memcpy for them.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
---
mm/zswap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index ca25b676048e..36898614ebcc 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -168,6 +168,7 @@ struct crypto_acomp_ctx {
struct crypto_wait wait;
u8 *buffer;
struct mutex mutex;
+ bool is_async; /* if acomp can sleep */
};

/*
@@ -716,6 +717,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
goto acomp_fail;
}
acomp_ctx->acomp = acomp;
+ acomp_ctx->is_async = acomp_is_async(acomp);

req = acomp_request_alloc(acomp_ctx->acomp);
if (!req) {
@@ -1370,7 +1372,7 @@ static void __zswap_load(struct zswap_entry *entry, struct page *page)
mutex_lock(&acomp_ctx->mutex);

src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
- if (!zpool_can_sleep_mapped(zpool)) {
+ if (acomp_ctx->is_async && !zpool_can_sleep_mapped(zpool)) {
memcpy(acomp_ctx->buffer, src, entry->length);
src = acomp_ctx->buffer;
zpool_unmap_handle(zpool, entry->handle);
@@ -1384,7 +1386,7 @@ static void __zswap_load(struct zswap_entry *entry, struct page *page)
BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
mutex_unlock(&acomp_ctx->mutex);

- if (zpool_can_sleep_mapped(zpool))
+ if (!acomp_ctx->is_async || zpool_can_sleep_mapped(zpool))
zpool_unmap_handle(zpool, entry->handle);
}

--
2.34.1