This version of check_zero is the same on non-zero areas,
but ~2 times faster on zero areas. Though benchmark was
done in userspace, memcmp may be different there
It is strange. Linux should provide a good function doing this.
Did I miss it?
Signed-off-by: Alexey Kuznetsov <kuz...@acronis.com>
---
fs/fuse/kio/pcs/pcs_cs_accel.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/fuse/kio/pcs/pcs_cs_accel.c b/fs/fuse/kio/pcs/pcs_cs_accel.c
index a76f28e..fc6a35f 100644
--- a/fs/fuse/kio/pcs/pcs_cs_accel.c
+++ b/fs/fuse/kio/pcs/pcs_cs_accel.c
@@ -278,13 +278,10 @@ static int verify_crc(struct pcs_int_request * ireq, u32
* crc)
static int check_zero(struct page * page, unsigned int offset)
{
u64 * addr = kmap(page) + offset;
- int i;
- for (i = 0; i < 512/8; i++) {
- if (likely(addr[i] != 0)) {
- kunmap(page);
- return 0;
- }
+ if (likely(addr[0] || memcmp(addr, addr + 1, 512 - 8))) {
+ kunmap(page);
+ return 0;
}
kunmap(page);
return 1;
--
1.8.3.1
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