Date:	Wed, 17 Mar 1999 23:54:53 -0800
From:	Yasushi Saito <yasushi@cs.washington.edu>
To:	linux-kernel@vger.rutgers.edu
Subject: disk head scheduling

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)


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