From mboxrd@z Thu Jan  1 00:00:00 1970
From: ron@ronnatalie.com (Ron Natalie)
Date: Mon, 20 Nov 2017 22:15:58 -0500
Subject: [TUHS] UNIX on S/370
In-Reply-To: <20171121025646.380EB18C0B0@mercury.lcs.mit.edu>
References: <20171121025646.380EB18C0B0@mercury.lcs.mit.edu>
Message-ID: <05e701d36277$0db803b0$29280b10$@ronnatalie.com>

That's a common optimization, but the only real requirement in the UNIX
kernel is the raw I/O bypasses the kernel buffer cache.


-----Original Message-----
From: TUHS [mailto:tuhs-bounces@minnie.tuhs.org] On Behalf Of Noel Chiappa
Sent: Monday, November 20, 2017 9:57 PM
To: tuhs at tuhs.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: [TUHS] UNIX on S/370

    > From: Larry McVoy

    > So tape I can see being more weird, but isn't raw disk just "don't put
    > it in buffer cache"?

One machines/controllers which are capable of it, with raw devices DMA
happens directly into the buffers in the process (which obviously has to be
resident while the I/O is happening).

    Noel