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Date:      Mon, 13 Nov 1995 23:25:53 -0800
From:      David Greenman <davidg@root.com>
To:        uhclem%nemesis@fw.ast.com (Frank Durda IV)
Cc:        simonm@dcs.gla.ac.uk, davidg@root.com, current@freebsd.org
Subject:   Re: Disk I/O that binds 
Message-ID:  <199511140725.XAA00188@corbin.Root.COM>
In-Reply-To: Your message of "Mon, 13 Nov 95 22:34:00 %2B0700." <m0tFD4o-000J7hC@nemesis.lonestar.org> 

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   Attached is the patch to disable disk block sorting. It's interesting -
I've been doing some tests here with disksort disabled and I'm actually seeing
a performance increase. I'm sure the algorithm is doing what it was written
to do...but...
   My (SCSI) drive supports tagged queueing, but even with that disabled
things seem to be a bit faster. Hmmm.

-DG

Index: ufs_disksubr.c
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ufs/ufs_disksubr.c,v
retrieving revision 1.19
diff -c -r1.19 ufs_disksubr.c
*** 1.19	1995/09/16 17:04:06
--- ufs_disksubr.c	1995/11/14 06:30:43
***************
*** 81,86 ****
--- 81,87 ----
  		return;
  	}
  
+ #if 0
  	/*
  	 * If we lie after the first (currently active) request, then we
  	 * must locate the second request list and add ourselves to it.
***************
*** 135,140 ****
--- 136,146 ----
  	 * Neither a second list nor a larger request... we go at the end of
  	 * the first list, which is the same as the end of the whole schebang.
  	 */
+ #endif
+ 
+ 	bq = ap->b_actf;
+ 	while (bq->b_actf)
+ 		bq = bq->b_actf;
  insert:
  	bp->b_actf = bq->b_actf;
  	bq->b_actf = bp;



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