net/ipv4/tcp_cdg.c

12  * Parameters window, backoff_beta, and backoff_factor are crucial for
16  * Except for window, knobs are configured via /sys/module/tcp_cdg/parameters/.
17  * Parameter window is only configurable when loading tcp_cdg as a module.
21  *   o Add toggle for shadow window mechanism. Suggested by David Hayes.
24  *     conversion is given by: backoff_factor = 1000/(G * window).
25  *   o Limit shadow window to 2 * cwnd, or to cwnd when application limited.
38 static int window __read_mostly = 8;
46 module_param(window, int, 0444);
47 MODULE_PARM_DESC(window, "gradient window size (power of two <= 256)");
58 MODULE_PARM_DESC(use_shadow, "use shadow window heuristic");
201 		ca->tail = (ca->tail + 1) & (window - 1);  in tcp_cdg_grad()
208 	 * (rtt_latest - rtt_oldest) / window.  in tcp_cdg_grad()
210 	 * We also drop division by window here.  in tcp_cdg_grad()
214 	/* Extrapolate missing values in gradient window: */  in tcp_cdg_grad()
216 		if (!ca->gradients && window > 1)  in tcp_cdg_grad()
217 			grad *= window; /* Memory allocation failed. */  in tcp_cdg_grad()
221 			grad = (grad * window) / (int)ca->tail;  in tcp_cdg_grad()
355 			memset(gradients, 0, window * sizeof(gradients[0]));  in tcp_cdg_cwnd_event()
379 	/* We silently fall back to window = 1 if allocation fails. */  in tcp_cdg_init()
380 	if (window > 1)  in tcp_cdg_init()
381 		ca->gradients = kcalloc(window, sizeof(ca->gradients[0]),  in tcp_cdg_init()
409 	if (backoff_beta > 1024 || window < 1 || window > 256)  in tcp_cdg_register()
411 	if (!is_power_of_2(window))  in tcp_cdg_register()