Paul Fulghum wrote:
As the tty flip buffer code has evolved, that delay value of 1 was carried along. It may have had some historical purpose, but I can't figure it out and it appears to have no use currently.
I looked further back and in the 2.4 kernels this scheduling was done with the timer task queue (process receive data on next timer tick). I guess the schedule_delayed_work() with a time delay of 1 was the best approximation of the previous behavior. There is no logical reason to delay the first attempt at processing receive data so schedule_delayed_work() in tty_schedule_flip() should be changed to 0 (as was the case for con_schedule_flip). The schedule_delayed_work in flush_to_ldisc() will continue to use a delay of 1 if the ldisc can't accept more data. This allows the user app and ldisc to catch up. Subsequent calls to tty_schedule_flip won't affect this 'back off' delay because once the work is scheduled (with a delay of 1) new scheduling calls are ignored for the same work structure. I've been testing the change to 0 in tty_schedule_flip() under various loads and data rates with no ill effects. -- Paul Fulghum Microgate Systems, Ltd. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
