On 03/10/2015 06:49 PM, George Spelvin wrote: > By the way, there's also a performance bug in tty_insert_flip_char. > If (tb->flags & TTYB_NORMAL), then tb->used is allowed to go up > to 2*tb->size, as the __tty_buffer_request_room code makes clear. > But tty_insert_flip_char() doesn't know that and will take the slow path > for the second half of every buffer. In practice, this doesn't happen because drivers that use tty_insert_flip_char() won't have compressed buffers (ie., TTYB_NORMAL). That's because tty_insert_flip_string_flags() will always get the uncompressed buffer flavor. That's to avoid buffer type hysteresis on a dirty line. Thanks for the careful analysis. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
