1 #include <linux/version.h>
2 #include <linux/types.h>
3 #include <linux/unistd.h>
4
5 #include <linux/sunrpc/clnt.h>
6 #include <linux/sunrpc/xprt.h>
7 #include <linux/sunrpc/timer.h>
8
9 #define RPC_RTO_MAX (60*HZ)
10 #define RPC_RTO_INIT (HZ/5)
11 #define RPC_RTO_MIN (HZ/10)
12
13 void
rpc_init_rtt(struct rpc_rtt * rt,long timeo)14 rpc_init_rtt(struct rpc_rtt *rt, long timeo)
15 {
16 long t = (timeo - RPC_RTO_INIT) << 3;
17 int i;
18 rt->timeo = timeo;
19 if (t < 0)
20 t = 0;
21 for (i = 0; i < 5; i++) {
22 rt->srtt[i] = t;
23 rt->sdrtt[i] = RPC_RTO_INIT;
24 }
25 memset(rt->ntimeouts, 0, sizeof(rt->ntimeouts));
26 }
27
28 void
rpc_update_rtt(struct rpc_rtt * rt,int timer,long m)29 rpc_update_rtt(struct rpc_rtt *rt, int timer, long m)
30 {
31 long *srtt, *sdrtt;
32
33 if (timer-- == 0)
34 return;
35
36 if (m == 0)
37 m = 1;
38 srtt = &rt->srtt[timer];
39 m -= *srtt >> 3;
40 *srtt += m;
41 if (m < 0)
42 m = -m;
43 sdrtt = &rt->sdrtt[timer];
44 m -= *sdrtt >> 2;
45 *sdrtt += m;
46 /* Set lower bound on the variance */
47 if (*sdrtt < RPC_RTO_MIN)
48 *sdrtt = RPC_RTO_MIN;
49 }
50
51 /*
52 * Estimate rto for an nfs rpc sent via. an unreliable datagram.
53 * Use the mean and mean deviation of rtt for the appropriate type of rpc
54 * for the frequent rpcs and a default for the others.
55 * The justification for doing "other" this way is that these rpcs
56 * happen so infrequently that timer est. would probably be stale.
57 * Also, since many of these rpcs are
58 * non-idempotent, a conservative timeout is desired.
59 * getattr, lookup,
60 * read, write, commit - A+4D
61 * other - timeo
62 */
63
64 long
rpc_calc_rto(struct rpc_rtt * rt,int timer)65 rpc_calc_rto(struct rpc_rtt *rt, int timer)
66 {
67 long res;
68 if (timer-- == 0)
69 return rt->timeo;
70 res = (rt->srtt[timer] >> 3) + rt->sdrtt[timer];
71 if (res > RPC_RTO_MAX)
72 res = RPC_RTO_MAX;
73 return res;
74 }
75