bcache: Delete some slower inline asm

Never saw a profile of bset_search_tree() where it wasn't bottlenecked
on memory until I got my new Haswell machine, but when I tried it there
it was suddenly burning 20% of the cpu in the inner loop on shrd...

Turns out, the version of shrd that takes 64 bit operands has a 9 cycle
latency. hah.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 6923be8db38c81f46e08adf66232169098c6ec40..3897a977428a12cb87cdafcf29a98409d8826da2 100644 (file)
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -481,16 +481,8 @@ static struct bkey *table_to_bkey(struct bset_tree *t, unsigned cacheline)
 
 static inline uint64_t shrd128(uint64_t high, uint64_t low, uint8_t shift)
 {
-#ifdef CONFIG_X86_64
-       asm("shrd %[shift],%[high],%[low]"
-           : [low] "+Rm" (low)
-           : [high] "R" (high),
-           [shift] "ci" (shift)
-           : "cc");
-#else
        low >>= shift;
        low  |= (high << 1) << (63U - shift);
-#endif
        return low;
 }