disk head scheduling

Yasushi Saito (yasushi@cs.washington.edu)
Wed, 17 Mar 1999 23:54:53 -0800

While studying IDE disk performance under high load in 2.2.2, I came
across a funny-looking line. I guess the below piece of code is
supposed to implement elevator seeking, but in fact it inserts
requests in random places when the disk head is moving toward the
sector 0. Am I missing something?

yaz

*** drivers/block/ll_rw_blk.c~ Mon Dec 28 11:19:19 1998
--- drivers/block/ll_rw_blk.c Wed Mar 17 20:37:18 1999
***************
*** 335,341 ****
const int before_next = IN_ORDER(req,tmp->next);

if (!IN_ORDER(tmp,tmp->next)) {
! if (after_current || before_next)
break;
} else {
if (after_current && before_next)
--- 335,341 ----
const int before_next = IN_ORDER(req,tmp->next);

if (!IN_ORDER(tmp,tmp->next)) {
! if (!(after_current || before_next))
break;
} else {
if (after_current && before_next)

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/