diff options
| -rw-r--r-- | drivers/char/hvc_console.c | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c index a0a88aa23f5b..fc9bc7709fd9 100644 --- a/drivers/char/hvc_console.c +++ b/drivers/char/hvc_console.c @@ -47,8 +47,6 @@ #define HVC_MAJOR 229 #define HVC_MINOR 0 -#define TIMEOUT (10) - /* * Wait this long per iteration while trying to push buffered data to the * hypervisor before allowing the tty to complete a close operation. @@ -550,6 +548,18 @@ static int hvc_chars_in_buffer(struct tty_struct *tty) return hp->n_outbuf; } +/* + * timeout will vary between the MIN and MAX values defined here. By default + * and during console activity we will use a default MIN_TIMEOUT of 10. When + * the console is idle, we increase the timeout value on each pass through + * msleep until we reach the max. This may be noticeable as a brief (average + * one second) delay on the console before the console responds to input when + * there has been no input for some time. + */ +#define MIN_TIMEOUT (10) +#define MAX_TIMEOUT (2000) +static u32 timeout = MIN_TIMEOUT; + #define HVC_POLL_READ 0x00000001 #define HVC_POLL_WRITE 0x00000002 @@ -642,9 +652,14 @@ static int hvc_poll(struct hvc_struct *hp) bail: spin_unlock_irqrestore(&hp->lock, flags); - if (read_total) + if (read_total) { + /* Activity is occurring, so reset the polling backoff value to + a minimum for performance. */ + timeout = MIN_TIMEOUT; + tty_flip_buffer_push(tty); - + } + return poll_mask; } @@ -688,8 +703,12 @@ int khvcd(void *unused) if (!hvc_kicked) { if (poll_mask == 0) schedule(); - else - msleep_interruptible(TIMEOUT); + else { + if (timeout < MAX_TIMEOUT) + timeout += (timeout >> 6) + 1; + + msleep_interruptible(timeout); + } } __set_current_state(TASK_RUNNING); } while (!kthread_should_stop()); |