Python and the need for speed

Paul Rubin no.email at nospam.invalid
Thu Apr 13 00:31:40 EDT 2017


Marko Rauhamaa <marko at pacujo.net> writes:
> Traditionally, disk access in Linux has been considered nonblocking.
> There is AIO, but that hasn't been used much. 

AIO is asynchronous but it's for dealing with already-opened files.
There doesn't seem to be a way to asynchronously OPEN a file.

> I believe the lack of asynchronous disk I/O is related to the grand
> Solaris idea which Linux adopted: all memory is on a disk and RAM is
> merely a cache.

And I thought Solaris's heritage involved NFS, with its notorious
infinite hard hangs if something happened on the server end.

> As swapping is no longer considered normal on modern computers, the
> memory-disk duality doesn't seem all that practical anymore. Rather,
> you'd like to treat the disk analogously to network access and keep RAM
> access separate.

Yep.  But opening disk files that way seems to require threads or extra
processes.


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