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From: Richard Kettlewell <invalid@invalid.invalid>
Newsgroups: comp.os.linux.misc
Subject: Re: Are We Back to the "Wars" Now ?
Date: Sun, 24 Nov 2024 19:14:59 +0000
Organization: terraraq NNTP server
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Lew Pitcher <lew.pitcher@digitalfreehold.ca> writes:
> On Sun, 24 Nov 2024 14:25:10 +0000, Rich wrote:
>> 186282@ud0s4.net <186283@ud0s4.net> wrote:
>>> On 11/23/24 4:25 PM, Lawrence D'Oliveiro wrote:
>>>> That’s irrelevant.  Pipes originated on the earliest Unix machine, 
>>>> which was a PDP-11 with only a 64kiB address space.  They work great 
>>>> for pumping around gigabytes of data, but you don’t need 
>>>> gigabyte-sized memory buffers to do that.
>>> 
>>>   It all has to be SOMEWHERE ... if not in RAM then
>>>   on a mass storage device.
>> 
>> Nope, at least not with pipes.
>
> Hold on a sec.... pipes are /buffered/ in RAM, so there's at least
> a small bit of ram set aside for each open pipe.

The word ‘all’ isn’t just decoration.  The claim was ‘it all has to be
somewhere’, and Rich’s point (as I understand it) is that it does not
all have to be somewhere.

For example,

  head -c $((1024*1024*1024)) /dev/urandom | sha256sum

puts a gigabyte of data through a pipe, but at no point does anything
allocate anywhere close to a gigabyte of storage of any kind.

-- 
https://www.greenend.org.uk/rjk/