diff options
Diffstat (limited to 'kernel/net.c')
| -rw-r--r-- | kernel/net.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/kernel/net.c b/kernel/net.c new file mode 100644 index 0000000..e5c396b --- /dev/null +++ b/kernel/net.c @@ -0,0 +1,248 @@ +/* + * net.c - network stuff for DNBD + * Copyright (C) 2006 Thorsten Zitterell <thorsten@zitterell.de> + */ + +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/random.h> + +#include "net.h" + +/* return pointer to server structure */ +dnbd_server_t *dnbd_get_server(dnbd_servers_t * servers, int id) +{ + if ((0 < id) && (id <= SERVERS_MAX)) + return &servers->serverlist[id - 1]; + else + return NULL; +} + +/* add a new server */ +int dnbd_set_serverid(dnbd_servers_t * servers, int id) +{ + int result = -EINVAL; + + dnbd_server_t *server; + + if (!(server = dnbd_get_server(servers, id))) + goto out; + + switch (server->state) { + case SERVER_INACTIVE: + break; + case SERVER_ACTIVE: + result = -EEXIST; + goto out; + case SERVER_STALLED: + server->state = SERVER_ACTIVE; + result = 0; + goto out; + } + + server->state = SERVER_ACTIVE; + server->id = id; + server->srtt = servers->timeout_min; + server->weight = 0; + server->last_rx = jiffies; + server->last_tx = jiffies; + + servers->count++; + result = 0; + out: + return result; +} + +/* return server according to their weights (= probability) */ +int dnbd_next_server(dnbd_servers_t * servers) +{ + int i; + char rnd; + dnbd_server_t *server = NULL; + int id = 0; + int weightsum = 0; + + /* get random byte from kernel */ + get_random_bytes(&rnd, 1); + + for (i = 0; i < SERVERS_MAX; i++) { + server = &servers->serverlist[i]; + if ((server->state == SERVER_ACTIVE) + && ((weightsum += server->weight) > (unsigned char) rnd)) { + id = server->id; + break; + } + } + + /* alternatively, use server with highest weight */ +/* for (i = 0; i < SERVERS_MAX; i++) { + server = &servers->serverlist[i]; + if ((server->state == SERVER_ACTIVE) + && (server->weight > weight)) + id = server->id; + }*/ + + return id; +} + +/* remove a server */ +void dnbd_rem_servers(dnbd_servers_t * servers) +{ + if (!servers->serverlist) + return; + + kfree(servers->serverlist); + servers->serverlist = NULL; +} + +/* remove all servers */ +void dnbd_clean_servers(dnbd_servers_t * servers) +{ + int i; + for (i = 0; i < SERVERS_MAX; i++) { + servers->serverlist[i].state = 0; + } + +} + +/* update round trip time of a server */ +void dnbd_rtt_server(dnbd_servers_t * servers, int id, int rtt) +{ + dnbd_server_t *server; + + if (!(server = dnbd_get_server(servers, id))) + goto out; + + if (rtt > servers->timeout_max) + rtt = TIMEOUT_MAX; + else if (rtt < servers->timeout_min) + rtt = TIMEOUT_MIN; + + down(&servers->sema); + server->srtt = ((SRTT_BETA * server->srtt + + (((SRTT_BETA_BASE - SRTT_BETA) * rtt) << SRTT_SHIFT)) + / SRTT_BETA_BASE); + up(&servers->sema); + + out: + return; +} + +/* recalculate server weights */ +void dnbd_servers_weight(dnbd_servers_t * servers) +{ + int i; + int num_servers = 0; + long weightsum = 0; + long prod = 0; + long asrtt = 0; + int srtt = 0; + dnbd_server_t *server; + + /* + * float arithmetics in kernel would be nice... + */ + down(&servers->sema); + + for (i = 0; i < SERVERS_MAX; i++) { + server = &servers->serverlist[i]; + + if (server->state == SERVER_ACTIVE) { + if (server->last_tx > + server->last_rx + servers->timeout_stalled) { + printk(KERN_ERR + "dnbd: disable server #%i\n", + i + 1); + server->state = SERVER_STALLED; + continue; + } + srtt = (server->srtt ? server->srtt : 1); + weightsum += WEIGHT_FACTOR / srtt; + asrtt += srtt; + num_servers++; + } + } + + if (!num_servers) + goto out; + + servers->asrtt = asrtt / num_servers; + + for (i = 0; i < SERVERS_MAX; i++) { + server = &servers->serverlist[i]; + + if (server->state == SERVER_ACTIVE) { + srtt = (server->srtt ? server->srtt : 1); + prod = srtt * weightsum; + + if (prod > 0) + server->weight = WEIGHT_NORMAL * WEIGHT_FACTOR / prod; + else + server->weight = WEIGHT_NORMAL / num_servers; + } + } + out: + up(&servers->sema); + +} + +/* fill buffer with server statistics in human readable form for /proc */ +int dnbd_show_servers(dnbd_servers_t * servers, void *buf, int size) +{ + int i, n = 0; + dnbd_server_t *server; + + n += snprintf(buf + n, size - n, + " timeout_min: %i jiffies\n timeout_max: %i jiffies\n", + servers->timeout_min, servers->timeout_max); + + n += snprintf(buf + n, size - n, "Average SRTT: %i\n", + servers->asrtt >> SRTT_SHIFT); + + for (i = 0; i < SERVERS_MAX; i++) { + server = &servers->serverlist[i]; + + switch (server->state) { + case SERVER_INACTIVE: + continue; + case SERVER_STALLED: + n += snprintf(buf + n, size - n, + " id: %i (stalled)\n", server->id); + continue; + default: + n += snprintf(buf + n, size - n, " id: %i\n", + server->id); + } + n += snprintf(buf + n, size - n, + " srtt: %i\n", server->srtt >> SRTT_SHIFT); + n += snprintf(buf + n, size - n, + " weight: %i (of %i)\n", server->weight,WEIGHT_NORMAL); + } + + return n; +} + +/* initialize servers */ +int dnbd_servers_init(dnbd_servers_t * servers) +{ + int i; + + spin_lock_init(&servers->lock); + init_MUTEX(&servers->sema); + + if (!(servers->serverlist = + (dnbd_server_t *) kmalloc(SERVERS_MAX * + sizeof(dnbd_server_t), + GFP_KERNEL))) + return -EINVAL; + + for (i = 0; i < SERVERS_MAX; i++) { + servers->serverlist[i].state = 0; + } + + servers->count = 0; + servers->timeout_min = TIMEOUT_MIN; + servers->timeout_max = TIMEOUT_MAX; + servers->timeout_stalled = TIMEOUT_STALLED; + return 0; +} |