From owner-freebsd-stable Mon Apr 20 09:10:59 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id JAA24896 for freebsd-stable-outgoing; Mon, 20 Apr 1998 09:10:59 -0700 (PDT) (envelope-from owner-freebsd-stable@FreeBSD.ORG) Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id QAA24763; Mon, 20 Apr 1998 16:10:31 GMT (envelope-from bde@godzilla.zeta.org.au) Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.7/8.8.7) id CAA04114; Tue, 21 Apr 1998 02:05:03 +1000 Date: Tue, 21 Apr 1998 02:05:03 +1000 From: Bruce Evans Message-Id: <199804201605.CAA04114@godzilla.zeta.org.au> To: bde@zeta.org.au, mike@smith.net.au Subject: Re: best wdc0 flags ? Cc: dburr@POBoxes.com, hardware@FreeBSD.ORG, stable@FreeBSD.ORG, Studded@san.rr.com Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk >> > I tried those flags and noticed that it turned on 32-bit transfers for >> >my wd0, resulting in a 20% increase in throughput. Out of curiosity, why >> >aren't these flags included in GENERIC? >> >> Becuase they break operation of drives that don't support them. > >Do we have any examples of controllers that don't? I thought I did, but my oldest accessible drive (all 400MB of it from 4 years ago) supports them. The probe seems to handle any that don't. Setting the multi-block flag is not such a good optimization, since it pessimizes throughput on some drives and it increases interrupt latency. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message