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tty: Keep the default buffering to sub-page units

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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@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox
2010-02-18 16:43:47 +00:00
committed by Greg Kroah-Hartman
parent 4165fe4ef7
commit d9661adfb8
2 changed files with 14 additions and 2 deletions
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6
drivers/char/tty_buffer.c
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@ -247,7 +247,8 @@ 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 goal = min(size - copied, TTY_BUFFER_PAGE);
int space = tty_buffer_request_room(tty, goal);
struct tty_buffer *tb = tty->buf.tail;
/* If there is no space then tb may be NULL */
if (unlikely(space == 0))
@ -283,7 +284,8 @@ int tty_insert_flip_string_flags(struct tty_struct *tty,
{
int copied = 0;
do {
int space = tty_buffer_request_room(tty, size - copied);
int goal = min(size - copied, TTY_BUFFER_PAGE);
int space = tty_buffer_request_room(tty, goal);
struct tty_buffer *tb = tty->buf.tail;
/* If there is no space then tb may be NULL */
if (unlikely(space == 0))