1/*- 2 * Copyright (c) 2001-2002 Luigi Rizzo 3 * 4 * Supported by: the Xorp Project (www.xorp.org) 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD$"); 30 31#include "opt_device_polling.h" 32 33#include <sys/param.h> 34#include <sys/systm.h> 35#include <sys/kernel.h> 36#include <sys/kthread.h> 37#include <sys/proc.h> 38#include <sys/eventhandler.h> 39#include <sys/resourcevar.h> 40#include <sys/socket.h> /* needed by net/if.h */ 41#include <sys/sockio.h> 42#include <sys/sysctl.h> 43#include <sys/syslog.h> 44 45#include <net/if.h> /* for IFF_* flags */ 46#include <net/netisr.h> /* for NETISR_POLL */ 47#include <net/vnet.h> 48 49void hardclock_device_poll(void); /* hook from hardclock */ 50 51static struct mtx poll_mtx; 52 53/* 54 * Polling support for [network] device drivers. 55 * 56 * Drivers which support this feature can register with the 57 * polling code. 58 * 59 * If registration is successful, the driver must disable interrupts, 60 * and further I/O is performed through the handler, which is invoked 61 * (at least once per clock tick) with 3 arguments: the "arg" passed at 62 * register time (a struct ifnet pointer), a command, and a "count" limit. 63 * 64 * The command can be one of the following: 65 * POLL_ONLY: quick move of "count" packets from input/output queues. 66 * POLL_AND_CHECK_STATUS: as above, plus check status registers or do 67 * other more expensive operations. This command is issued periodically 68 * but less frequently than POLL_ONLY. 69 * 70 * The count limit specifies how much work the handler can do during the 71 * call -- typically this is the number of packets to be received, or 72 * transmitted, etc. (drivers are free to interpret this number, as long 73 * as the max time spent in the function grows roughly linearly with the 74 * count). 75 * 76 * Polling is enabled and disabled via setting IFCAP_POLLING flag on 77 * the interface. The driver ioctl handler should register interface 78 * with polling and disable interrupts, if registration was successful. 79 * 80 * A second variable controls the sharing of CPU between polling/kernel 81 * network processing, and other activities (typically userlevel tasks): 82 * kern.polling.user_frac (between 0 and 100, default 50) sets the share 83 * of CPU allocated to user tasks. CPU is allocated proportionally to the 84 * shares, by dynamically adjusting the "count" (poll_burst). 85 * 86 * Other parameters can should be left to their default values. 87 * The following constraints hold 88 * 89 * 1 <= poll_each_burst <= poll_burst <= poll_burst_max 90 * MIN_POLL_BURST_MAX <= poll_burst_max <= MAX_POLL_BURST_MAX 91 */ 92 93#define MIN_POLL_BURST_MAX 10 94#define MAX_POLL_BURST_MAX 20000 95 96static uint32_t poll_burst = 5; 97static uint32_t poll_burst_max = 150; /* good for 100Mbit net and HZ=1000 */ 98static uint32_t poll_each_burst = 5; 99 100static SYSCTL_NODE(_kern, OID_AUTO, polling, CTLFLAG_RW, 0, 101 "Device polling parameters"); 102 103SYSCTL_UINT(_kern_polling, OID_AUTO, burst, CTLFLAG_RD, 104 &poll_burst, 0, "Current polling burst size"); 105 106static int netisr_poll_scheduled; 107static int netisr_pollmore_scheduled; 108static int poll_shutting_down; 109 110static int poll_burst_max_sysctl(SYSCTL_HANDLER_ARGS) 111{ 112 uint32_t val = poll_burst_max; 113 int error; 114 115 error = sysctl_handle_int(oidp, &val, 0, req); 116 if (error || !req->newptr ) 117 return (error); 118 if (val < MIN_POLL_BURST_MAX || val > MAX_POLL_BURST_MAX) 119 return (EINVAL); 120 121 mtx_lock(&poll_mtx); 122 poll_burst_max = val; 123 if (poll_burst > poll_burst_max) 124 poll_burst = poll_burst_max; 125 if (poll_each_burst > poll_burst_max) 126 poll_each_burst = MIN_POLL_BURST_MAX; 127 mtx_unlock(&poll_mtx); 128 129 return (0); 130} 131SYSCTL_PROC(_kern_polling, OID_AUTO, burst_max, CTLTYPE_UINT | CTLFLAG_RW, 132 0, sizeof(uint32_t), poll_burst_max_sysctl, "I", "Max Polling burst size"); 133 134static int poll_each_burst_sysctl(SYSCTL_HANDLER_ARGS) 135{ 136 uint32_t val = poll_each_burst; 137 int error; 138 139 error = sysctl_handle_int(oidp, &val, 0, req); 140 if (error || !req->newptr ) 141 return (error); 142 if (val < 1) 143 return (EINVAL); 144 145 mtx_lock(&poll_mtx); 146 if (val > poll_burst_max) { 147 mtx_unlock(&poll_mtx); 148 return (EINVAL); 149 } 150 poll_each_burst = val; 151 mtx_unlock(&poll_mtx); 152 153 return (0); 154} 155SYSCTL_PROC(_kern_polling, OID_AUTO, each_burst, CTLTYPE_UINT | CTLFLAG_RW, 156 0, sizeof(uint32_t), poll_each_burst_sysctl, "I", 157 "Max size of each burst"); 158 159static uint32_t poll_in_idle_loop=0; /* do we poll in idle loop ? */ 160SYSCTL_UINT(_kern_polling, OID_AUTO, idle_poll, CTLFLAG_RW, 161 &poll_in_idle_loop, 0, "Enable device polling in idle loop"); 162 163static uint32_t user_frac = 50; 164static int user_frac_sysctl(SYSCTL_HANDLER_ARGS) 165{ 166 uint32_t val = user_frac; 167 int error; 168 169 error = sysctl_handle_int(oidp, &val, 0, req); 170 if (error || !req->newptr ) 171 return (error); 172 if (val > 99) 173 return (EINVAL); 174 175 mtx_lock(&poll_mtx); 176 user_frac = val; 177 mtx_unlock(&poll_mtx); 178 179 return (0); 180} 181SYSCTL_PROC(_kern_polling, OID_AUTO, user_frac, CTLTYPE_UINT | CTLFLAG_RW, 182 0, sizeof(uint32_t), user_frac_sysctl, "I", 183 "Desired user fraction of cpu time"); 184 185static uint32_t reg_frac_count = 0; 186static uint32_t reg_frac = 20 ; 187static int reg_frac_sysctl(SYSCTL_HANDLER_ARGS) 188{ 189 uint32_t val = reg_frac; 190 int error; 191 192 error = sysctl_handle_int(oidp, &val, 0, req); 193 if (error || !req->newptr ) 194 return (error); 195 if (val < 1 || val > hz) 196 return (EINVAL); 197 198 mtx_lock(&poll_mtx); 199 reg_frac = val; 200 if (reg_frac_count >= reg_frac) 201 reg_frac_count = 0; 202 mtx_unlock(&poll_mtx); 203 204 return (0); 205} 206SYSCTL_PROC(_kern_polling, OID_AUTO, reg_frac, CTLTYPE_UINT | CTLFLAG_RW, 207 0, sizeof(uint32_t), reg_frac_sysctl, "I", 208 "Every this many cycles check registers"); 209 210static uint32_t short_ticks; 211SYSCTL_UINT(_kern_polling, OID_AUTO, short_ticks, CTLFLAG_RD, 212 &short_ticks, 0, "Hardclock ticks shorter than they should be"); 213 214static uint32_t lost_polls; 215SYSCTL_UINT(_kern_polling, OID_AUTO, lost_polls, CTLFLAG_RD, 216 &lost_polls, 0, "How many times we would have lost a poll tick"); 217 218static uint32_t pending_polls; 219SYSCTL_UINT(_kern_polling, OID_AUTO, pending_polls, CTLFLAG_RD, 220 &pending_polls, 0, "Do we need to poll again"); 221 222static int residual_burst = 0; 223SYSCTL_INT(_kern_polling, OID_AUTO, residual_burst, CTLFLAG_RD, 224 &residual_burst, 0, "# of residual cycles in burst"); 225 226static uint32_t poll_handlers; /* next free entry in pr[]. */ 227SYSCTL_UINT(_kern_polling, OID_AUTO, handlers, CTLFLAG_RD, 228 &poll_handlers, 0, "Number of registered poll handlers"); 229 230static uint32_t phase; 231SYSCTL_UINT(_kern_polling, OID_AUTO, phase, CTLFLAG_RD, 232 &phase, 0, "Polling phase"); 233 234static uint32_t suspect; 235SYSCTL_UINT(_kern_polling, OID_AUTO, suspect, CTLFLAG_RD, 236 &suspect, 0, "suspect event"); 237 238static uint32_t stalled; 239SYSCTL_UINT(_kern_polling, OID_AUTO, stalled, CTLFLAG_RD, 240 &stalled, 0, "potential stalls"); 241 242static uint32_t idlepoll_sleeping; /* idlepoll is sleeping */ 243SYSCTL_UINT(_kern_polling, OID_AUTO, idlepoll_sleeping, CTLFLAG_RD, 244 &idlepoll_sleeping, 0, "idlepoll is sleeping"); 245 246 247#define POLL_LIST_LEN 128 248struct pollrec { 249 poll_handler_t *handler; 250 struct ifnet *ifp; 251}; 252 253static struct pollrec pr[POLL_LIST_LEN]; 254 255static void 256poll_shutdown(void *arg, int howto) 257{ 258 259 poll_shutting_down = 1; 260} 261 262static void 263init_device_poll(void) 264{ 265 266 mtx_init(&poll_mtx, "polling", NULL, MTX_DEF); 267 EVENTHANDLER_REGISTER(shutdown_post_sync, poll_shutdown, NULL, 268 SHUTDOWN_PRI_LAST); 269} 270SYSINIT(device_poll, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, init_device_poll, NULL); 271 272 273/* 274 * Hook from hardclock. Tries to schedule a netisr, but keeps track 275 * of lost ticks due to the previous handler taking too long. 276 * Normally, this should not happen, because polling handler should 277 * run for a short time. However, in some cases (e.g. when there are 278 * changes in link status etc.) the drivers take a very long time 279 * (even in the order of milliseconds) to reset and reconfigure the 280 * device, causing apparent lost polls. 281 * 282 * The first part of the code is just for debugging purposes, and tries 283 * to count how often hardclock ticks are shorter than they should, 284 * meaning either stray interrupts or delayed events. 285 */ 286void 287hardclock_device_poll(void) 288{ 289 static struct timeval prev_t, t; 290 int delta; 291 292 if (poll_handlers == 0 || poll_shutting_down) 293 return; 294 295 microuptime(&t); 296 delta = (t.tv_usec - prev_t.tv_usec) + 297 (t.tv_sec - prev_t.tv_sec)*1000000; 298 if (delta * hz < 500000) 299 short_ticks++; 300 else 301 prev_t = t; 302 303 if (pending_polls > 100) { 304 /* 305 * Too much, assume it has stalled (not always true 306 * see comment above). 307 */ 308 stalled++; 309 pending_polls = 0; 310 phase = 0; 311 } 312 313 if (phase <= 2) { 314 if (phase != 0) 315 suspect++; 316 phase = 1; 317 netisr_poll_scheduled = 1; 318 netisr_pollmore_scheduled = 1; 319 netisr_sched_poll(); 320 phase = 2; 321 } 322 if (pending_polls++ > 0) 323 lost_polls++; 324} 325 326/* 327 * ether_poll is called from the idle loop. 328 */ 329static void 330ether_poll(int count) 331{ 332 int i; 333 334 mtx_lock(&poll_mtx); 335 336 if (count > poll_each_burst) 337 count = poll_each_burst; 338 339 for (i = 0 ; i < poll_handlers ; i++) 340 pr[i].handler(pr[i].ifp, POLL_ONLY, count); 341 342 mtx_unlock(&poll_mtx); 343} 344 345/* 346 * netisr_pollmore is called after other netisr's, possibly scheduling 347 * another NETISR_POLL call, or adapting the burst size for the next cycle. 348 * 349 * It is very bad to fetch large bursts of packets from a single card at once, 350 * because the burst could take a long time to be completely processed, or 351 * could saturate the intermediate queue (ipintrq or similar) leading to 352 * losses or unfairness. To reduce the problem, and also to account better for 353 * time spent in network-related processing, we split the burst in smaller 354 * chunks of fixed size, giving control to the other netisr's between chunks. 355 * This helps in improving the fairness, reducing livelock (because we 356 * emulate more closely the "process to completion" that we have with 357 * fastforwarding) and accounting for the work performed in low level 358 * handling and forwarding. 359 */ 360 361static struct timeval poll_start_t; 362 363void 364netisr_pollmore() 365{ 366 struct timeval t; 367 int kern_load; 368 369 mtx_lock(&poll_mtx); 370 if (!netisr_pollmore_scheduled) { 371 mtx_unlock(&poll_mtx); 372 return; 373 } 374 netisr_pollmore_scheduled = 0; 375 phase = 5; 376 if (residual_burst > 0) { 377 netisr_poll_scheduled = 1; 378 netisr_pollmore_scheduled = 1; 379 netisr_sched_poll(); 380 mtx_unlock(&poll_mtx); 381 /* will run immediately on return, followed by netisrs */ 382 return; 383 } 384 /* here we can account time spent in netisr's in this tick */ 385 microuptime(&t); 386 kern_load = (t.tv_usec - poll_start_t.tv_usec) + 387 (t.tv_sec - poll_start_t.tv_sec)*1000000; /* us */ 388 kern_load = (kern_load * hz) / 10000; /* 0..100 */ 389 if (kern_load > (100 - user_frac)) { /* try decrease ticks */ 390 if (poll_burst > 1) 391 poll_burst--; 392 } else { 393 if (poll_burst < poll_burst_max) 394 poll_burst++; 395 } 396 397 pending_polls--; 398 if (pending_polls == 0) /* we are done */ 399 phase = 0; 400 else { 401 /* 402 * Last cycle was long and caused us to miss one or more 403 * hardclock ticks. Restart processing again, but slightly 404 * reduce the burst size to prevent that this happens again. 405 */ 406 poll_burst -= (poll_burst / 8); 407 if (poll_burst < 1) 408 poll_burst = 1; 409 netisr_poll_scheduled = 1; 410 netisr_pollmore_scheduled = 1; 411 netisr_sched_poll(); 412 phase = 6; 413 } 414 mtx_unlock(&poll_mtx); 415} 416 417/* 418 * netisr_poll is typically scheduled once per tick. 419 */ 420void 421netisr_poll(void) 422{ 423 int i, cycles; 424 enum poll_cmd arg = POLL_ONLY; 425 426 mtx_lock(&poll_mtx); 427 if (!netisr_poll_scheduled) { 428 mtx_unlock(&poll_mtx); 429 return; 430 } 431 netisr_poll_scheduled = 0; 432 phase = 3; 433 if (residual_burst == 0) { /* first call in this tick */ 434 microuptime(&poll_start_t); 435 if (++reg_frac_count == reg_frac) { 436 arg = POLL_AND_CHECK_STATUS; 437 reg_frac_count = 0; 438 } 439 440 residual_burst = poll_burst; 441 } 442 cycles = (residual_burst < poll_each_burst) ? 443 residual_burst : poll_each_burst; 444 residual_burst -= cycles; 445 446 for (i = 0 ; i < poll_handlers ; i++) 447 pr[i].handler(pr[i].ifp, arg, cycles); 448 449 phase = 4; 450 mtx_unlock(&poll_mtx); 451} 452 453/* 454 * Try to register routine for polling. Returns 0 if successful 455 * (and polling should be enabled), error code otherwise. 456 * A device is not supposed to register itself multiple times. 457 * 458 * This is called from within the *_ioctl() functions. 459 */ 460int 461ether_poll_register(poll_handler_t *h, struct ifnet *ifp) 462{ 463 int i; 464 465 KASSERT(h != NULL, ("%s: handler is NULL", __func__)); 466 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 467 468 mtx_lock(&poll_mtx); 469 if (poll_handlers >= POLL_LIST_LEN) { 470 /* 471 * List full, cannot register more entries. 472 * This should never happen; if it does, it is probably a 473 * broken driver trying to register multiple times. Checking 474 * this at runtime is expensive, and won't solve the problem 475 * anyways, so just report a few times and then give up. 476 */ 477 static int verbose = 10 ; 478 if (verbose >0) { 479 log(LOG_ERR, "poll handlers list full, " 480 "maybe a broken driver ?\n"); 481 verbose--; 482 } 483 mtx_unlock(&poll_mtx); 484 return (ENOMEM); /* no polling for you */ 485 } 486 487 for (i = 0 ; i < poll_handlers ; i++) 488 if (pr[i].ifp == ifp && pr[i].handler != NULL) { 489 mtx_unlock(&poll_mtx); 490 log(LOG_DEBUG, "ether_poll_register: %s: handler" 491 " already registered\n", ifp->if_xname); 492 return (EEXIST); 493 } 494 495 pr[poll_handlers].handler = h; 496 pr[poll_handlers].ifp = ifp; 497 poll_handlers++; 498 mtx_unlock(&poll_mtx); 499 if (idlepoll_sleeping) 500 wakeup(&idlepoll_sleeping); 501 return (0); 502} 503 504/* 505 * Remove interface from the polling list. Called from *_ioctl(), too. 506 */ 507int 508ether_poll_deregister(struct ifnet *ifp) 509{ 510 int i; 511 512 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 513 514 mtx_lock(&poll_mtx); 515 516 for (i = 0 ; i < poll_handlers ; i++) 517 if (pr[i].ifp == ifp) /* found it */ 518 break; 519 if (i == poll_handlers) { 520 log(LOG_DEBUG, "ether_poll_deregister: %s: not found!\n", 521 ifp->if_xname); 522 mtx_unlock(&poll_mtx); 523 return (ENOENT); 524 } 525 poll_handlers--; 526 if (i < poll_handlers) { /* Last entry replaces this one. */ 527 pr[i].handler = pr[poll_handlers].handler; 528 pr[i].ifp = pr[poll_handlers].ifp; 529 } 530 mtx_unlock(&poll_mtx); 531 return (0); 532} 533 534static void 535poll_idle(void) 536{ 537 struct thread *td = curthread; 538 struct rtprio rtp; 539 540 rtp.prio = RTP_PRIO_MAX; /* lowest priority */ 541 rtp.type = RTP_PRIO_IDLE; 542 PROC_SLOCK(td->td_proc); 543 rtp_to_pri(&rtp, td); 544 PROC_SUNLOCK(td->td_proc); 545 546 for (;;) { 547 if (poll_in_idle_loop && poll_handlers > 0) { 548 idlepoll_sleeping = 0; 549 ether_poll(poll_each_burst); 550 thread_lock(td); 551 mi_switch(SW_VOL, NULL); 552 thread_unlock(td); 553 } else { 554 idlepoll_sleeping = 1; 555 tsleep(&idlepoll_sleeping, 0, "pollid", hz * 3); 556 } 557 } 558} 559 560static struct proc *idlepoll; 561static struct kproc_desc idlepoll_kp = { 562 "idlepoll", 563 poll_idle, 564 &idlepoll 565}; 566SYSINIT(idlepoll, SI_SUB_KTHREAD_VM, SI_ORDER_ANY, kproc_start, 567 &idlepoll_kp); 568