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Message-Id: <20231213-zswap-dstmem-v1-1-896763369d04@bytedance.com>
Date: Wed, 13 Dec 2023 04:17:58 +0000
From: Chengming Zhou <zhouchengming@...edance.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Nhat Pham <nphamcs@...il.com>, Chris Li <chriscli@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
Seth Jennings <sjenning@...hat.com>,
Dan Streetman <ddstreet@...e.org>,
Vitaly Wool <vitaly.wool@...sulko.com>,
Yosry Ahmed <yosryahmed@...gle.com>
Cc: Nhat Pham <nphamcs@...il.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Chengming Zhou <zhouchengming@...edance.com>
Subject: [PATCH 1/5] mm/zswap: reuse dstmem when decompress
In the !zpool_can_sleep_mapped() case such as zsmalloc, we need to first
copy the entry->handle memory to a temporary memory, which is allocated
using kmalloc.
Obviously we can reuse the per-compressor dstmem to avoid allocating
every time, since it's percpu-compressor and protected in mutex.
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
Reviewed-by: Nhat Pham <nphamcs@...il.com>
---
mm/zswap.c | 29 +++++++++--------------------
1 file changed, 9 insertions(+), 20 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index 7ee54a3d8281..edb8b45ed5a1 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1772,9 +1772,9 @@ bool zswap_load(struct folio *folio)
struct zswap_entry *entry;
struct scatterlist input, output;
struct crypto_acomp_ctx *acomp_ctx;
- u8 *src, *dst, *tmp;
+ unsigned int dlen = PAGE_SIZE;
+ u8 *src, *dst;
struct zpool *zpool;
- unsigned int dlen;
bool ret;
VM_WARN_ON_ONCE(!folio_test_locked(folio));
@@ -1796,27 +1796,18 @@ bool zswap_load(struct folio *folio)
goto stats;
}
- zpool = zswap_find_zpool(entry);
- if (!zpool_can_sleep_mapped(zpool)) {
- tmp = kmalloc(entry->length, GFP_KERNEL);
- if (!tmp) {
- ret = false;
- goto freeentry;
- }
- }
-
/* decompress */
- dlen = PAGE_SIZE;
- src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
+ acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
+ mutex_lock(acomp_ctx->mutex);
+ zpool = zswap_find_zpool(entry);
+ src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
if (!zpool_can_sleep_mapped(zpool)) {
- memcpy(tmp, src, entry->length);
- src = tmp;
+ memcpy(acomp_ctx->dstmem, src, entry->length);
+ src = acomp_ctx->dstmem;
zpool_unmap_handle(zpool, entry->handle);
}
- acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
- mutex_lock(acomp_ctx->mutex);
sg_init_one(&input, src, entry->length);
sg_init_table(&output, 1);
sg_set_page(&output, page, PAGE_SIZE, 0);
@@ -1827,15 +1818,13 @@ bool zswap_load(struct folio *folio)
if (zpool_can_sleep_mapped(zpool))
zpool_unmap_handle(zpool, entry->handle);
- else
- kfree(tmp);
ret = true;
stats:
count_vm_event(ZSWPIN);
if (entry->objcg)
count_objcg_event(entry->objcg, ZSWPIN);
-freeentry:
+
spin_lock(&tree->lock);
if (ret && zswap_exclusive_loads_enabled) {
zswap_invalidate_entry(tree, entry);
--
b4 0.10.1
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