[RFC PATCH v1 7/8] zram: optimize memory operations with clear_page()/copy_page()

[Jiang Liu]

Signed-off-by: Jiang Liu <jiang....@huawei.com>
---
 drivers/staging/zram/zram_drv.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 64b51b9..b079af5 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -128,23 +128,26 @@ static void zram_free_page(struct zram *zram, size_t 
index)
        meta->table[index].size = 0;
 }
 
+static inline int is_partial_io(struct bio_vec *bvec)
+{
+       return bvec->bv_len != PAGE_SIZE;
+}
+
 static void handle_zero_page(struct bio_vec *bvec)
 {
        struct page *page = bvec->bv_page;
        void *user_mem;
 
        user_mem = kmap_atomic(page);
-       memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
+       if (is_partial_io(bvec))
+               memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
+       else
+               clear_page(user_mem);
        kunmap_atomic(user_mem);
 
        flush_dcache_page(page);
 }
 
-static inline int is_partial_io(struct bio_vec *bvec)
-{
-       return bvec->bv_len != PAGE_SIZE;
-}
-
 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
 {
        int ret = LZO_E_OK;
@@ -154,13 +157,13 @@ static int zram_decompress_page(struct zram *zram, char 
*mem, u32 index)
        unsigned long handle = meta->table[index].handle;
 
        if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
-               memset(mem, 0, PAGE_SIZE);
+               clear_page(mem);
                return 0;
        }
 
        cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
        if (meta->table[index].size == PAGE_SIZE)
-               memcpy(mem, cmem, PAGE_SIZE);
+               copy_page(mem, cmem);
        else
                ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
                                                mem, &clen);
@@ -309,11 +312,13 @@ static int zram_bvec_write(struct zram *zram, struct 
bio_vec *bvec, u32 index,
        }
        cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
 
-       if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
+       if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
                src = kmap_atomic(page);
-       memcpy(cmem, src, clen);
-       if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
+               copy_page(cmem, src);
                kunmap_atomic(src);
+       } else {
+               memcpy(cmem, src, clen);
+       }
 
        zs_unmap_object(meta->mem_pool, handle);
 
-- 
1.8.1.2

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