[TUHS] UNIX on S/370

Ron Natalie ron at ronnatalie.com
Tue Nov 21 13:15:58 AEST 2017


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 at 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



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