21 Nov
2017
21 Nov
'17
9:15 a.m.
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(a)tuhs.org
Cc: jnc(a)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