Re: [PATCH] tty: Keep the default buffering to sub-page units

[Greg KH]

On Wed, Feb 17, 2010 at 01:04:53PM +0000, Alan Cox wrote:
> We allocate during interrupts so while our buffering is normally diced up
> small anyway on some hardware at speed we can pressure the VM excessively
> for page pairs. We don't really need big buffers to be linear so don't try
> so hard.
> 
> In order to make this work well we will tidy up excess callers to request_room,
> which cannot itself enforce this break up.
> 
> Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
> ---
> 
>  drivers/char/tty_buffer.c |    5 +++--
>  include/linux/tty.h       |   10 ++++++++++
>  2 files changed, 13 insertions(+), 2 deletions(-)
> 
> 
> diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c
> index 66fa4e1..8402eda 100644
> --- a/drivers/char/tty_buffer.c
> +++ b/drivers/char/tty_buffer.c
> @@ -247,7 +247,7 @@ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
>  {
>  	int copied = 0;
>  	do {
> -		int space = tty_buffer_request_room(tty, size - copied);
> +		int space = tty_buffer_request_room(tty, goal);

This causes the build error:

  CC      drivers/char/tty_buffer.o
drivers/char/tty_buffer.c: In function âtty_insert_flip_stringâ:
drivers/char/tty_buffer.c:250: error: âgoalâ undeclared (first use in this function)
drivers/char/tty_buffer.c:250: error: (Each undeclared identifier is reported only once
drivers/char/tty_buffer.c:250: error: for each function it appears in.)

So I'll drop it for now.

Care to fix this?

thanks,

greg k-h
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