I should drink more coffee before starting committing. Revert the last change
[dragonfly.git] / sys / kern / lwkt_ipiq.c
blob1149b0d8e60ae75d2e32d94030188c04f6bc0281
1 /*
2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
34 * $DragonFly: src/sys/kern/lwkt_ipiq.c,v 1.27 2008/05/18 20:57:56 nth Exp $
38 * This module implements IPI message queueing and the MI portion of IPI
39 * message processing.
42 #include "opt_ddb.h"
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/proc.h>
48 #include <sys/rtprio.h>
49 #include <sys/queue.h>
50 #include <sys/thread2.h>
51 #include <sys/sysctl.h>
52 #include <sys/ktr.h>
53 #include <sys/kthread.h>
54 #include <machine/cpu.h>
55 #include <sys/lock.h>
56 #include <sys/caps.h>
58 #include <vm/vm.h>
59 #include <vm/vm_param.h>
60 #include <vm/vm_kern.h>
61 #include <vm/vm_object.h>
62 #include <vm/vm_page.h>
63 #include <vm/vm_map.h>
64 #include <vm/vm_pager.h>
65 #include <vm/vm_extern.h>
66 #include <vm/vm_zone.h>
68 #include <machine/stdarg.h>
69 #include <machine/smp.h>
70 #include <machine/atomic.h>
72 #ifdef SMP
73 static __int64_t ipiq_count; /* total calls to lwkt_send_ipiq*() */
74 static __int64_t ipiq_fifofull; /* number of fifo full conditions detected */
75 static __int64_t ipiq_avoided; /* interlock with target avoids cpu ipi */
76 static __int64_t ipiq_passive; /* passive IPI messages */
77 static __int64_t ipiq_cscount; /* number of cpu synchronizations */
78 static int ipiq_optimized = 1; /* XXX temporary sysctl */
79 #ifdef PANIC_DEBUG
80 static int panic_ipiq_cpu = -1;
81 static int panic_ipiq_count = 100;
82 #endif
83 #endif
85 #ifdef SMP
86 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_count, CTLFLAG_RW, &ipiq_count, 0, "");
87 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_fifofull, CTLFLAG_RW, &ipiq_fifofull, 0, "");
88 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_avoided, CTLFLAG_RW, &ipiq_avoided, 0, "");
89 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_passive, CTLFLAG_RW, &ipiq_passive, 0, "");
90 SYSCTL_QUAD(_lwkt, OID_AUTO, ipiq_cscount, CTLFLAG_RW, &ipiq_cscount, 0, "");
91 SYSCTL_INT(_lwkt, OID_AUTO, ipiq_optimized, CTLFLAG_RW, &ipiq_optimized, 0, "");
92 #ifdef PANIC_DEBUG
93 SYSCTL_INT(_lwkt, OID_AUTO, panic_ipiq_cpu, CTLFLAG_RW, &panic_ipiq_cpu, 0, "");
94 SYSCTL_INT(_lwkt, OID_AUTO, panic_ipiq_count, CTLFLAG_RW, &panic_ipiq_count, 0, "");
95 #endif
97 #define IPIQ_STRING "func=%p arg1=%p arg2=%d scpu=%d dcpu=%d"
98 #define IPIQ_ARG_SIZE (sizeof(void *) * 2 + sizeof(int) * 3)
100 #if !defined(KTR_IPIQ)
101 #define KTR_IPIQ KTR_ALL
102 #endif
103 KTR_INFO_MASTER(ipiq);
104 KTR_INFO(KTR_IPIQ, ipiq, send_norm, 0, IPIQ_STRING, IPIQ_ARG_SIZE);
105 KTR_INFO(KTR_IPIQ, ipiq, send_pasv, 1, IPIQ_STRING, IPIQ_ARG_SIZE);
106 KTR_INFO(KTR_IPIQ, ipiq, send_nbio, 2, IPIQ_STRING, IPIQ_ARG_SIZE);
107 KTR_INFO(KTR_IPIQ, ipiq, send_fail, 3, IPIQ_STRING, IPIQ_ARG_SIZE);
108 KTR_INFO(KTR_IPIQ, ipiq, receive, 4, IPIQ_STRING, IPIQ_ARG_SIZE);
109 KTR_INFO(KTR_IPIQ, ipiq, sync_start, 5, "cpumask=%08x", sizeof(cpumask_t));
110 KTR_INFO(KTR_IPIQ, ipiq, sync_add, 6, "cpumask=%08x", sizeof(cpumask_t));
111 KTR_INFO(KTR_IPIQ, ipiq, cpu_send, 7, IPIQ_STRING, IPIQ_ARG_SIZE);
112 KTR_INFO(KTR_IPIQ, ipiq, send_end, 8, IPIQ_STRING, IPIQ_ARG_SIZE);
114 #define logipiq(name, func, arg1, arg2, sgd, dgd) \
115 KTR_LOG(ipiq_ ## name, func, arg1, arg2, sgd->gd_cpuid, dgd->gd_cpuid)
116 #define logipiq2(name, arg) \
117 KTR_LOG(ipiq_ ## name, arg)
119 #endif /* SMP */
121 #ifdef SMP
123 static int lwkt_process_ipiq_core(globaldata_t sgd, lwkt_ipiq_t ip,
124 struct intrframe *frame);
125 static void lwkt_cpusync_remote1(lwkt_cpusync_t poll);
126 static void lwkt_cpusync_remote2(lwkt_cpusync_t poll);
129 * Send a function execution request to another cpu. The request is queued
130 * on the cpu<->cpu ipiq matrix. Each cpu owns a unique ipiq FIFO for every
131 * possible target cpu. The FIFO can be written.
133 * If the FIFO fills up we have to enable interrupts to avoid an APIC
134 * deadlock and process pending IPIQs while waiting for it to empty.
135 * Otherwise we may soft-deadlock with another cpu whos FIFO is also full.
137 * We can safely bump gd_intr_nesting_level because our crit_exit() at the
138 * end will take care of any pending interrupts.
140 * The actual hardware IPI is avoided if the target cpu is already processing
141 * the queue from a prior IPI. It is possible to pipeline IPI messages
142 * very quickly between cpus due to the FIFO hysteresis.
144 * Need not be called from a critical section.
147 lwkt_send_ipiq3(globaldata_t target, ipifunc3_t func, void *arg1, int arg2)
149 lwkt_ipiq_t ip;
150 int windex;
151 struct globaldata *gd = mycpu;
153 logipiq(send_norm, func, arg1, arg2, gd, target);
155 if (target == gd) {
156 func(arg1, arg2, NULL);
157 logipiq(send_end, func, arg1, arg2, gd, target);
158 return(0);
160 crit_enter();
161 ++gd->gd_intr_nesting_level;
162 #ifdef INVARIANTS
163 if (gd->gd_intr_nesting_level > 20)
164 panic("lwkt_send_ipiq: TOO HEAVILY NESTED!");
165 #endif
166 KKASSERT(curthread->td_pri >= TDPRI_CRIT);
167 ++ipiq_count;
168 ip = &gd->gd_ipiq[target->gd_cpuid];
171 * Do not allow the FIFO to become full. Interrupts must be physically
172 * enabled while we liveloop to avoid deadlocking the APIC.
174 if (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 2) {
175 unsigned int eflags = read_eflags();
177 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) {
178 logipiq(cpu_send, func, arg1, arg2, gd, target);
179 cpu_send_ipiq(target->gd_cpuid);
181 cpu_enable_intr();
182 ++ipiq_fifofull;
183 while (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 4) {
184 KKASSERT(ip->ip_windex - ip->ip_rindex != MAXCPUFIFO - 1);
185 lwkt_process_ipiq();
187 write_eflags(eflags);
191 * Queue the new message
193 windex = ip->ip_windex & MAXCPUFIFO_MASK;
194 ip->ip_func[windex] = func;
195 ip->ip_arg1[windex] = arg1;
196 ip->ip_arg2[windex] = arg2;
197 cpu_sfence();
198 ++ip->ip_windex;
199 --gd->gd_intr_nesting_level;
202 * signal the target cpu that there is work pending.
204 if (atomic_poll_acquire_int(&ip->ip_npoll)) {
205 logipiq(cpu_send, func, arg1, arg2, gd, target);
206 cpu_send_ipiq(target->gd_cpuid);
207 } else {
208 if (ipiq_optimized == 0) {
209 logipiq(cpu_send, func, arg1, arg2, gd, target);
210 cpu_send_ipiq(target->gd_cpuid);
211 } else {
212 ++ipiq_avoided;
215 crit_exit();
217 logipiq(send_end, func, arg1, arg2, gd, target);
218 return(ip->ip_windex);
222 * Similar to lwkt_send_ipiq() but this function does not actually initiate
223 * the IPI to the target cpu unless the FIFO has become too full, so it is
224 * very fast.
226 * This function is used for non-critical IPI messages, such as memory
227 * deallocations. The queue will typically be flushed by the target cpu at
228 * the next clock interrupt.
230 * Need not be called from a critical section.
233 lwkt_send_ipiq3_passive(globaldata_t target, ipifunc3_t func,
234 void *arg1, int arg2)
236 lwkt_ipiq_t ip;
237 int windex;
238 struct globaldata *gd = mycpu;
240 KKASSERT(target != gd);
241 crit_enter();
242 logipiq(send_pasv, func, arg1, arg2, gd, target);
243 ++gd->gd_intr_nesting_level;
244 #ifdef INVARIANTS
245 if (gd->gd_intr_nesting_level > 20)
246 panic("lwkt_send_ipiq: TOO HEAVILY NESTED!");
247 #endif
248 KKASSERT(curthread->td_pri >= TDPRI_CRIT);
249 ++ipiq_count;
250 ++ipiq_passive;
251 ip = &gd->gd_ipiq[target->gd_cpuid];
254 * Do not allow the FIFO to become full. Interrupts must be physically
255 * enabled while we liveloop to avoid deadlocking the APIC.
257 if (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 2) {
258 unsigned int eflags = read_eflags();
260 if (atomic_poll_acquire_int(&ip->ip_npoll) || ipiq_optimized == 0) {
261 logipiq(cpu_send, func, arg1, arg2, gd, target);
262 cpu_send_ipiq(target->gd_cpuid);
264 cpu_enable_intr();
265 ++ipiq_fifofull;
266 while (ip->ip_windex - ip->ip_rindex > MAXCPUFIFO / 4) {
267 KKASSERT(ip->ip_windex - ip->ip_rindex != MAXCPUFIFO - 1);
268 lwkt_process_ipiq();
270 write_eflags(eflags);
274 * Queue the new message
276 windex = ip->ip_windex & MAXCPUFIFO_MASK;
277 ip->ip_func[windex] = func;
278 ip->ip_arg1[windex] = arg1;
279 ip->ip_arg2[windex] = arg2;
280 cpu_sfence();
281 ++ip->ip_windex;
282 --gd->gd_intr_nesting_level;
285 * Do not signal the target cpu, it will pick up the IPI when it next
286 * polls (typically on the next tick).
288 crit_exit();
290 logipiq(send_end, func, arg1, arg2, gd, target);
291 return(ip->ip_windex);
295 * Send an IPI request without blocking, return 0 on success, ENOENT on
296 * failure. The actual queueing of the hardware IPI may still force us
297 * to spin and process incoming IPIs but that will eventually go away
298 * when we've gotten rid of the other general IPIs.
301 lwkt_send_ipiq3_nowait(globaldata_t target, ipifunc3_t func,
302 void *arg1, int arg2)
304 lwkt_ipiq_t ip;
305 int windex;
306 struct globaldata *gd = mycpu;
308 logipiq(send_nbio, func, arg1, arg2, gd, target);
309 KKASSERT(curthread->td_pri >= TDPRI_CRIT);
310 if (target == gd) {
311 func(arg1, arg2, NULL);
312 logipiq(send_end, func, arg1, arg2, gd, target);
313 return(0);
315 ++ipiq_count;
316 ip = &gd->gd_ipiq[target->gd_cpuid];
318 if (ip->ip_windex - ip->ip_rindex >= MAXCPUFIFO * 2 / 3) {
319 logipiq(send_fail, func, arg1, arg2, gd, target);
320 return(ENOENT);
322 windex = ip->ip_windex & MAXCPUFIFO_MASK;
323 ip->ip_func[windex] = func;
324 ip->ip_arg1[windex] = arg1;
325 ip->ip_arg2[windex] = arg2;
326 cpu_sfence();
327 ++ip->ip_windex;
330 * This isn't a passive IPI, we still have to signal the target cpu.
332 if (atomic_poll_acquire_int(&ip->ip_npoll)) {
333 logipiq(cpu_send, func, arg1, arg2, gd, target);
334 cpu_send_ipiq(target->gd_cpuid);
335 } else {
336 if (ipiq_optimized == 0) {
337 logipiq(cpu_send, func, arg1, arg2, gd, target);
338 cpu_send_ipiq(target->gd_cpuid);
339 } else {
340 ++ipiq_avoided;
344 logipiq(send_end, func, arg1, arg2, gd, target);
345 return(0);
349 * deprecated, used only by fast int forwarding.
352 lwkt_send_ipiq3_bycpu(int dcpu, ipifunc3_t func, void *arg1, int arg2)
354 return(lwkt_send_ipiq3(globaldata_find(dcpu), func, arg1, arg2));
358 * Send a message to several target cpus. Typically used for scheduling.
359 * The message will not be sent to stopped cpus.
362 lwkt_send_ipiq3_mask(u_int32_t mask, ipifunc3_t func, void *arg1, int arg2)
364 int cpuid;
365 int count = 0;
367 mask &= ~stopped_cpus;
368 while (mask) {
369 cpuid = bsfl(mask);
370 lwkt_send_ipiq3(globaldata_find(cpuid), func, arg1, arg2);
371 mask &= ~(1 << cpuid);
372 ++count;
374 return(count);
378 * Wait for the remote cpu to finish processing a function.
380 * YYY we have to enable interrupts and process the IPIQ while waiting
381 * for it to empty or we may deadlock with another cpu. Create a CPU_*()
382 * function to do this! YYY we really should 'block' here.
384 * MUST be called from a critical section. This routine may be called
385 * from an interrupt (for example, if an interrupt wakes a foreign thread
386 * up).
388 void
389 lwkt_wait_ipiq(globaldata_t target, int seq)
391 lwkt_ipiq_t ip;
392 int maxc = 100000000;
394 if (target != mycpu) {
395 ip = &mycpu->gd_ipiq[target->gd_cpuid];
396 if ((int)(ip->ip_xindex - seq) < 0) {
397 unsigned int eflags = read_eflags();
398 cpu_enable_intr();
399 while ((int)(ip->ip_xindex - seq) < 0) {
400 crit_enter();
401 lwkt_process_ipiq();
402 crit_exit();
403 if (--maxc == 0)
404 kprintf("LWKT_WAIT_IPIQ WARNING! %d wait %d (%d)\n", mycpu->gd_cpuid, target->gd_cpuid, ip->ip_xindex - seq);
405 if (maxc < -1000000)
406 panic("LWKT_WAIT_IPIQ");
408 * xindex may be modified by another cpu, use a load fence
409 * to ensure that the loop does not use a speculative value
410 * (which may improve performance).
412 cpu_lfence();
414 write_eflags(eflags);
420 lwkt_seq_ipiq(globaldata_t target)
422 lwkt_ipiq_t ip;
424 ip = &mycpu->gd_ipiq[target->gd_cpuid];
425 return(ip->ip_windex);
429 * Called from IPI interrupt (like a fast interrupt), which has placed
430 * us in a critical section. The MP lock may or may not be held.
431 * May also be called from doreti or splz, or be reentrantly called
432 * indirectly through the ip_func[] we run.
434 * There are two versions, one where no interrupt frame is available (when
435 * called from the send code and from splz, and one where an interrupt
436 * frame is available.
438 void
439 lwkt_process_ipiq(void)
441 globaldata_t gd = mycpu;
442 globaldata_t sgd;
443 lwkt_ipiq_t ip;
444 int n;
446 again:
447 for (n = 0; n < ncpus; ++n) {
448 if (n != gd->gd_cpuid) {
449 sgd = globaldata_find(n);
450 ip = sgd->gd_ipiq;
451 if (ip != NULL) {
452 while (lwkt_process_ipiq_core(sgd, &ip[gd->gd_cpuid], NULL))
457 if (gd->gd_cpusyncq.ip_rindex != gd->gd_cpusyncq.ip_windex) {
458 if (lwkt_process_ipiq_core(gd, &gd->gd_cpusyncq, NULL)) {
459 if (gd->gd_curthread->td_cscount == 0)
460 goto again;
461 need_ipiq();
466 void
467 lwkt_process_ipiq_frame(struct intrframe *frame)
469 globaldata_t gd = mycpu;
470 globaldata_t sgd;
471 lwkt_ipiq_t ip;
472 int n;
474 again:
475 for (n = 0; n < ncpus; ++n) {
476 if (n != gd->gd_cpuid) {
477 sgd = globaldata_find(n);
478 ip = sgd->gd_ipiq;
479 if (ip != NULL) {
480 while (lwkt_process_ipiq_core(sgd, &ip[gd->gd_cpuid], frame))
485 if (gd->gd_cpusyncq.ip_rindex != gd->gd_cpusyncq.ip_windex) {
486 if (lwkt_process_ipiq_core(gd, &gd->gd_cpusyncq, frame)) {
487 if (gd->gd_curthread->td_cscount == 0)
488 goto again;
489 need_ipiq();
494 static int
495 lwkt_process_ipiq_core(globaldata_t sgd, lwkt_ipiq_t ip,
496 struct intrframe *frame)
498 int ri;
499 int wi;
500 ipifunc3_t copy_func;
501 void *copy_arg1;
502 int copy_arg2;
505 * Obtain the current write index, which is modified by a remote cpu.
506 * Issue a load fence to prevent speculative reads of e.g. data written
507 * by the other cpu prior to it updating the index.
509 KKASSERT(curthread->td_pri >= TDPRI_CRIT);
510 wi = ip->ip_windex;
511 cpu_lfence();
514 * Note: xindex is only updated after we are sure the function has
515 * finished execution. Beware lwkt_process_ipiq() reentrancy! The
516 * function may send an IPI which may block/drain.
518 * Note: due to additional IPI operations that the callback function
519 * may make, it is possible for both rindex and windex to advance and
520 * thus for rindex to advance passed our cached windex.
522 while (wi - (ri = ip->ip_rindex) > 0) {
523 ri &= MAXCPUFIFO_MASK;
524 copy_func = ip->ip_func[ri];
525 copy_arg1 = ip->ip_arg1[ri];
526 copy_arg2 = ip->ip_arg2[ri];
527 cpu_mfence();
528 ++ip->ip_rindex;
529 KKASSERT((ip->ip_rindex & MAXCPUFIFO_MASK) == ((ri + 1) & MAXCPUFIFO_MASK));
530 logipiq(receive, copy_func, copy_arg1, copy_arg2, sgd, mycpu);
531 copy_func(copy_arg1, copy_arg2, frame);
532 cpu_sfence();
533 ip->ip_xindex = ip->ip_rindex;
535 #ifdef PANIC_DEBUG
537 * Simulate panics during the processing of an IPI
539 if (mycpu->gd_cpuid == panic_ipiq_cpu && panic_ipiq_count) {
540 if (--panic_ipiq_count == 0) {
541 #ifdef DDB
542 Debugger("PANIC_DEBUG");
543 #else
544 panic("PANIC_DEBUG");
545 #endif
548 #endif
552 * Return non-zero if there are more IPI messages pending on this
553 * ipiq. ip_npoll is left set as long as possible to reduce the
554 * number of IPIs queued by the originating cpu, but must be cleared
555 * *BEFORE* checking windex.
557 atomic_poll_release_int(&ip->ip_npoll);
558 return(wi != ip->ip_windex);
561 static void
562 lwkt_sync_ipiq(void *arg)
564 cpumask_t *cpumask = arg;
566 atomic_clear_int(cpumask, mycpu->gd_cpumask);
567 if (*cpumask == 0)
568 wakeup(cpumask);
571 void
572 lwkt_synchronize_ipiqs(const char *wmesg)
574 cpumask_t other_cpumask;
576 other_cpumask = mycpu->gd_other_cpus & smp_active_mask;
577 lwkt_send_ipiq_mask(other_cpumask, lwkt_sync_ipiq, &other_cpumask);
579 crit_enter();
580 while (other_cpumask != 0) {
581 tsleep_interlock(&other_cpumask);
582 if (other_cpumask != 0)
583 tsleep(&other_cpumask, 0, wmesg, 0);
585 crit_exit();
588 #endif
591 * CPU Synchronization Support
593 * lwkt_cpusync_simple()
595 * The function is executed synchronously before return on remote cpus.
596 * A lwkt_cpusync_t pointer is passed as an argument. The data can
597 * be accessed via arg->cs_data.
599 * XXX should I just pass the data as an argument to be consistent?
602 void
603 lwkt_cpusync_simple(cpumask_t mask, cpusync_func_t func, void *data)
605 struct lwkt_cpusync cmd;
607 cmd.cs_run_func = NULL;
608 cmd.cs_fin1_func = func;
609 cmd.cs_fin2_func = NULL;
610 cmd.cs_data = data;
611 lwkt_cpusync_start(mask & mycpu->gd_other_cpus, &cmd);
612 if (mask & (1 << mycpu->gd_cpuid))
613 func(&cmd);
614 lwkt_cpusync_finish(&cmd);
618 * lwkt_cpusync_fastdata()
620 * The function is executed in tandem with return on remote cpus.
621 * The data is directly passed as an argument. Do not pass pointers to
622 * temporary storage as the storage might have
623 * gone poof by the time the target cpu executes
624 * the function.
626 * At the moment lwkt_cpusync is declared on the stack and we must wait
627 * for all remote cpus to ack in lwkt_cpusync_finish(), but as a future
628 * optimization we should be able to put a counter in the globaldata
629 * structure (if it is not otherwise being used) and just poke it and
630 * return without waiting. XXX
632 void
633 lwkt_cpusync_fastdata(cpumask_t mask, cpusync_func2_t func, void *data)
635 struct lwkt_cpusync cmd;
637 cmd.cs_run_func = NULL;
638 cmd.cs_fin1_func = NULL;
639 cmd.cs_fin2_func = func;
640 cmd.cs_data = NULL;
641 lwkt_cpusync_start(mask & mycpu->gd_other_cpus, &cmd);
642 if (mask & (1 << mycpu->gd_cpuid))
643 func(data);
644 lwkt_cpusync_finish(&cmd);
648 * lwkt_cpusync_start()
650 * Start synchronization with a set of target cpus, return once they are
651 * known to be in a synchronization loop. The target cpus will execute
652 * poll->cs_run_func() IN TANDEM WITH THE RETURN.
654 * XXX future: add lwkt_cpusync_start_quick() and require a call to
655 * lwkt_cpusync_add() or lwkt_cpusync_wait(), allowing the caller to
656 * potentially absorb the IPI latency doing something useful.
658 void
659 lwkt_cpusync_start(cpumask_t mask, lwkt_cpusync_t poll)
661 globaldata_t gd = mycpu;
663 poll->cs_count = 0;
664 poll->cs_mask = mask;
665 #ifdef SMP
666 logipiq2(sync_start, mask & gd->gd_other_cpus);
667 poll->cs_maxcount = lwkt_send_ipiq_mask(
668 mask & gd->gd_other_cpus & smp_active_mask,
669 (ipifunc1_t)lwkt_cpusync_remote1, poll);
670 #endif
671 if (mask & gd->gd_cpumask) {
672 if (poll->cs_run_func)
673 poll->cs_run_func(poll);
675 #ifdef SMP
676 if (poll->cs_maxcount) {
677 ++ipiq_cscount;
678 ++gd->gd_curthread->td_cscount;
679 while (poll->cs_count != poll->cs_maxcount) {
680 crit_enter();
681 lwkt_process_ipiq();
682 crit_exit();
685 #endif
688 void
689 lwkt_cpusync_add(cpumask_t mask, lwkt_cpusync_t poll)
691 globaldata_t gd = mycpu;
692 #ifdef SMP
693 int count;
694 #endif
696 mask &= ~poll->cs_mask;
697 poll->cs_mask |= mask;
698 #ifdef SMP
699 logipiq2(sync_add, mask & gd->gd_other_cpus);
700 count = lwkt_send_ipiq_mask(
701 mask & gd->gd_other_cpus & smp_active_mask,
702 (ipifunc1_t)lwkt_cpusync_remote1, poll);
703 #endif
704 if (mask & gd->gd_cpumask) {
705 if (poll->cs_run_func)
706 poll->cs_run_func(poll);
708 #ifdef SMP
709 poll->cs_maxcount += count;
710 if (poll->cs_maxcount) {
711 if (poll->cs_maxcount == count)
712 ++gd->gd_curthread->td_cscount;
713 while (poll->cs_count != poll->cs_maxcount) {
714 crit_enter();
715 lwkt_process_ipiq();
716 crit_exit();
719 #endif
723 * Finish synchronization with a set of target cpus. The target cpus will
724 * execute cs_fin1_func(poll) prior to this function returning, and will
725 * execute cs_fin2_func(data) IN TANDEM WITH THIS FUNCTION'S RETURN.
727 * If cs_maxcount is non-zero then we are mastering a cpusync with one or
728 * more remote cpus and must account for it in our thread structure.
730 void
731 lwkt_cpusync_finish(lwkt_cpusync_t poll)
733 globaldata_t gd = mycpu;
735 poll->cs_count = -1;
736 if (poll->cs_mask & gd->gd_cpumask) {
737 if (poll->cs_fin1_func)
738 poll->cs_fin1_func(poll);
739 if (poll->cs_fin2_func)
740 poll->cs_fin2_func(poll->cs_data);
742 #ifdef SMP
743 if (poll->cs_maxcount) {
744 while (poll->cs_count != -(poll->cs_maxcount + 1)) {
745 crit_enter();
746 lwkt_process_ipiq();
747 crit_exit();
749 --gd->gd_curthread->td_cscount;
751 #endif
754 #ifdef SMP
757 * helper IPI remote messaging function.
759 * Called on remote cpu when a new cpu synchronization request has been
760 * sent to us. Execute the run function and adjust cs_count, then requeue
761 * the request so we spin on it.
763 static void
764 lwkt_cpusync_remote1(lwkt_cpusync_t poll)
766 atomic_add_int(&poll->cs_count, 1);
767 if (poll->cs_run_func)
768 poll->cs_run_func(poll);
769 lwkt_cpusync_remote2(poll);
773 * helper IPI remote messaging function.
775 * Poll for the originator telling us to finish. If it hasn't, requeue
776 * our request so we spin on it. When the originator requests that we
777 * finish we execute cs_fin1_func(poll) synchronously and cs_fin2_func(data)
778 * in tandem with the release.
780 static void
781 lwkt_cpusync_remote2(lwkt_cpusync_t poll)
783 if (poll->cs_count < 0) {
784 cpusync_func2_t savef;
785 void *saved;
787 if (poll->cs_fin1_func)
788 poll->cs_fin1_func(poll);
789 if (poll->cs_fin2_func) {
790 savef = poll->cs_fin2_func;
791 saved = poll->cs_data;
792 atomic_add_int(&poll->cs_count, -1);
793 savef(saved);
794 } else {
795 atomic_add_int(&poll->cs_count, -1);
797 } else {
798 globaldata_t gd = mycpu;
799 lwkt_ipiq_t ip;
800 int wi;
802 ip = &gd->gd_cpusyncq;
803 wi = ip->ip_windex & MAXCPUFIFO_MASK;
804 ip->ip_func[wi] = (ipifunc3_t)(ipifunc1_t)lwkt_cpusync_remote2;
805 ip->ip_arg1[wi] = poll;
806 ip->ip_arg2[wi] = 0;
807 cpu_sfence();
808 ++ip->ip_windex;
812 #endif