Re: M-x grep significantly slower in emacs 22 (compared to emacs 21)

[Eli Zaretskii]

> Date: Thu, 27 Sep 2007 11:50:35 +0200 (METDST)
> From: Philippe Waroquiers <wao@cfmu.eurocontrol.int>
> Cc: philippe.waroquiers@eurocontrol.int
> 
> 
> M-x grep (on a big file) is much slower with emacs 22 than with emacs 21.
> I verified this on an emacs 22 compiled on hp-ux
> and on emacs 22 compiled on gnu/linux.
> The grep returns about 1900 lines.
> 
> performances on gnu-linux (x86, 3 GHz) (elapsed time)
> emacs 21: +-2 seconds
> emacs 22: +-10 seconds
> 
> performances on hp (pa-risc workstation, 400 Mhz) (elapsed time)
> emacs 21: +-10 seconds
> emacs 22: +-82 seconds
> 
> While the M-x grep was running (for the hp test), I used the "top" command 
> to see what was going on. 
> grep was sleeping most of the time, and emacs was sleeping then running
> then sleeping then running. The proportion of sleep time was significant
> (I would say: about 80% of the time sleeping).

Thank you for your report.

Does it help to customize the value process-adaptive-read-buffering?