Re: Any idea about what makes Emacs slow reading on pipes?

[Andreas Schwab <schwab@suse.de>]

David.Kastrup@t-online.de (David Kastrup) writes:

|> The following exhibits abysmal speed within Emacs:
|> 
|> (let (process-connection-type) (switch-to-buffer (generate-new-buffer
|> "*test*"))(erase-buffer)(start-process "test" (current-buffer) "sh"
|> "-c" "hexdump -v /dev/zero|dd bs=1 count=100k")(erase-buffer))
|> 
|> More to the point, things start out dead slow and get faster later.
|> It is not the fault of the programs on the sending side: just piping
|> into cat >/dev/null instead of Emacs is much much faster.  It does
|> not seem that setting process-connection-type to nil as above (using
|> a pipe instead of a pty) does help worth noting.
|> 
|> The system I see this in is
|> GNU Emacs 21.3.50.3 (i686-pc-linux-gnu)
|> a RedHat 9 system, but I have seen this in practically every Linux
|> system up to now.  Is this a Linux-specific problem, or do others see
|> this as well?

I cannot reproduce that on ppc-suse-linux.  I also tried out MacOS X on
the same machine, and there the overall speed is much lower, but still
mostly constant.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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