linux-kernel - Re: [PATCH v2 6/9] n_tty: Process echoes in blocks

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Message-ID: <20130723235329.GA14499@kroah.com>
Date:	Tue, 23 Jul 2013 16:53:29 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH v2 6/9] n_tty: Process echoes in blocks

On Sat, Jun 15, 2013 at 10:04:26AM -0400, Peter Hurley wrote:
> Byte-by-byte echo output is painfully slow, requiring a lock/unlock
> cycle for every input byte.
> 
> Instead, perform the echo output in blocks of 256 characters, and
> at least once per flip buffer receive. Enough space is reserved in
> the echo buffer to guarantee a full block can be saved without
> overrunning the echo output. Overrun is prevented by discarding
> the oldest echoes until enough space exists in the echo buffer
> to receive at least a full block of new echoes.

I'm a bit worried about this, I wonder if anything is expecting the
echos to not come in "bursts" like this, but I really can't think of why
they would want that.

So let's apply it and see what breaks!  :)

thanks,

greg k-h
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