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Subject[PATCH v3 09/10] zram: optimize memory operations with clear_page()/copy_page()
Date
Some architectures provides architecture-specific, optimized version of
clear_page()/copy_page(), which may have better performance than
memset()/memcpy(). So use clear_page()/copy_page() to optimize zram
performance if possible.

Signed-off-by: Jiang Liu <jiang.liu@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 5e6545a..b4f84b6b 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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