From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id c0114d18 for ; Wed, 9 Jan 2019 04:24:50 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 17E7FA35E9; Wed, 9 Jan 2019 14:24:48 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id C475CA35C7; Wed, 9 Jan 2019 14:24:11 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (2048-bit key; unprotected) header.d=bsdimp-com.20150623.gappssmtp.com header.i=@bsdimp-com.20150623.gappssmtp.com header.b="gF/+D1qK"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 38B2DA35C7; Wed, 9 Jan 2019 14:24:08 +1000 (AEST) Received: from mail-qk1-f174.google.com (mail-qk1-f174.google.com [209.85.222.174]) by minnie.tuhs.org (Postfix) with ESMTPS id 4758EA35C4 for ; Wed, 9 Jan 2019 14:24:07 +1000 (AEST) Received: by mail-qk1-f174.google.com with SMTP id d15so3736527qkj.0 for ; Tue, 08 Jan 2019 20:24:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=w9SpynXS1C2WHqNmwCrrI9AlQ8Lh3NdsVzuHCn+WF+0=; b=gF/+D1qKldfOdKaX41LYZjQANwTcvqcHXBA6DKeBdEQz4gQzCL0XamH5qSNKcQnr2I MAcSyDPhg272NZCS+eaIDnm2uQQfjYUzCc248/zRe5MYIq1VXcKhfGb4gt+9Xe+liH4a DfA7nihC1/6j9PhScAkySy9Ca4i5niu9LshNTLW8h2G5zbFhIgiGf+oyHWOBOb6+Z5Vf 0w34s5L+hj5qnPVvPXmLdbirEUDM66VLz1e9Bm32Iak+EgAKhPWviVidKmbs5tJx8Gha sHc52J0nyDWXFcaRuAbr86IU28b7Bi5E3CL5koytTzmMWFotzY2q55MPJlSTt2I91IeH f8iQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=w9SpynXS1C2WHqNmwCrrI9AlQ8Lh3NdsVzuHCn+WF+0=; b=Rg9Hj4VEiK0nVXk4rjSboVkxCCs+b7VdE/wA/3SlQpBBmrPN3ByehpbbshHql4/bce yyIfsXaQKquL2aZUdqfMzkx4v6XBCUyD1llFbB1lg/gcr6Wt0NxPnhg3rsaUfvhbtDdx 7d5y//yE0H9nYRKjcZUvFw1O5SRLZuqz58JXOeDYlJMwIqZK2SfGeUOr2tvxj5y0uMcS alW2CDwUg2c7j127tT/06P/O1BlbrIpUBKHpk/enjAMaIrWJmM9NKCraKUUIRZOKiZEO CgGJE4uoEANkCapzyLbiqtmkb3BS9QuoyHVwTXTokJ/bEeJRnCSCWzpchGzna8+oOjZU lkvg== X-Gm-Message-State: AJcUukdaX1LqDzSxwPH0clFKM2159IYs3TLY3Q9EpPW28qdzuD46tKaz 2+3PqT6ftGhuOrmMc5ehcJT0O5T5TB7r/VaIDYCWpw7k X-Google-Smtp-Source: ALg8bN6k5usgJ+LvBlCOIslC/1UhoSgsBQ+2Cwozcme5s1UxMCcoJzWPd3wWmCM47pv5FSG6S2zQ2/sJ4WAjqv7Io6k= X-Received: by 2002:a37:6e86:: with SMTP id j128mr4177751qkc.46.1547007846163; Tue, 08 Jan 2019 20:24:06 -0800 (PST) MIME-Version: 1.0 References: <966501A7-7736-4EB0-841A-C1516C876272@quintile.net> In-Reply-To: From: Warner Losh Date: Tue, 8 Jan 2019 21:23:54 -0700 Message-ID: To: Dave Horsfall Content-Type: multipart/alternative; boundary="00000000000022c11a057efed58c" Subject: Re: [TUHS] TUHS Digest, Vol 38, Issue 10 X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: The Eunuchs Hysterical Society Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --00000000000022c11a057efed58c Content-Type: text/plain; charset="UTF-8" On Tue, Jan 8, 2019, 7:11 PM Dave Horsfall On Tue, 8 Jan 2019, Warner Losh wrote: > > > i understood that this implemented the elevator algorithm, and > > possible rotational latency compensation. > > > > > > I know what it does. I want to know why that specific name was selected. > > Err, because as I replied in a previous message (did you not see it?), it > was up to the programmer to implement an optimal strategy to access the > sectors, depending upon the device? I'm not being snarky, but it seems > like an obvious choice (if not a hint) to me... > > Let's see, I need a strategy to optimise access, taking into account > seek and rotational latency. I know! I'll call it XXstrategy()! > > For example, I could envisage a disk where the sectors are deliberately > not numbered sequentially i.e. they've taken rotational latency into > account for you? > > Out of interest, what would you have called it? XXaccess(), perhaps? > The name seems obvious because I've seen it for the last 30 years. But I've not seen it used elsewhere, nor have I seen it documented except in relationship to Unix. It could have been called blkio or bufio or bio or even just work or morework and still been as meaningful. VMS uses the FDT table to process the IRPs sent down. RT-11 has a series of entry points that have boring names. Other systems have a start routine (though more often that is a common routine used by both the queue me and isr functions). There is a wide diversity here... Warner > --00000000000022c11a057efed58c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


= On Tue, Jan 8, 2019, 7:11 PM Dave Horsfall <dave@horsfall.org wrote:<= br>
On Tue, 8 Jan 2019, Warner Losh wro= te:

>=C2=A0 =C2=A0 =C2=A0 =C2=A0i understood that this implemented the eleva= tor algorithm, and
>=C2=A0 =C2=A0 =C2=A0 =C2=A0possible rotational latency compensation. >
>
> I know what it does. I want to know why that specific name was selecte= d.

Err, because as I replied in a previous message (did you not see it?), it <= br> was up to the programmer to implement an optimal strategy to access the sectors, depending upon the device?=C2=A0 I'm not being snarky, but it = seems
like an obvious choice (if not a hint) to me...

Let's see, I need a strategy to optimise access, taking into account seek and rotational latency.=C2=A0 I know!=C2=A0 I'll call it XXstrateg= y()!

For example, I could envisage a disk where the sectors are deliberately not numbered sequentially i.e. they've taken rotational latency into account for you?

Out of interest, what would you have called it?=C2=A0 XXaccess(), perhaps?<= br>

T= he name seems obvious because I've seen it for the last 30 years. But I= 've not seen it used elsewhere, nor have I seen it documented except in= relationship to Unix. It could have been called blkio or bufio or bio or e= ven just work or morework and still been as meaningful. VMS uses the FDT ta= ble to process the IRPs sent down. RT-11 has a series of entry points that = have boring names. Other systems have a start routine (though more often th= at is a common routine used by both the queue me and isr functions). There = is a wide diversity here...

Warner
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