linux-kernel - Re: [PATCH] detour TTY driver

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Message-Id: <1277516912.29797.411.camel@itpsd6lap>
Date:	Sat, 26 Jun 2010 03:48:31 +0200
From:	Samo Pogacnik <samo_pogacnik@....net>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	linux-embedded <linux-embedded@...r.kernel.org>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] detour TTY driver - now ttyprintk

> > +static int tpk_write_room(struct tty_struct *tty)
> > +{
> > +	int ret = tpk_space;
> > +
> > +	/* allow char by char under max pressure */
> > +	if (tpk_space == 0)
> > +		tpk_space = 1;
> 
> That won't do what you think, the ldisc will keep seeing progress and
> generate millions of 1 byte I/Os in a loop !

I thought that this would automatically reduce processor load, which is
obviously not the case. Sorry for the delay, but i am trying to figure
out how to slow down write method when under pressure.

And that setting tpk_space to 1 would then be just in case we reach 0 to
enable further processing.

Samo


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