-/*
- * Copyright (c) 2009 The Regents of the University of California
+/* Copyright (c) 2009, 2012 The Regents of the University of California
* Barret Rhoden <brho@cs.berkeley.edu>
* See LICENSE for details.
*
- * Scheduling and dispatching.
- */
-
-#ifdef __SHARC__
-#pragma nosharc
-#endif
+ * Scheduling and dispatching. */
#include <schedule.h>
+#include <corerequest.h>
#include <process.h>
#include <monitor.h>
#include <stdio.h>
#include <assert.h>
#include <atomic.h>
+#include <smp.h>
+#include <manager.h>
+#include <alarm.h>
#include <sys/queue.h>
+#include <arsc_server.h>
+#include <hashtable.h>
+
+/* Process Lists. 'unrunnable' is a holding list for SCPs that are running or
+ * waiting or otherwise not considered for sched decisions. */
+struct proc_list unrunnable_scps = TAILQ_HEAD_INITIALIZER(unrunnable_scps);
+struct proc_list runnable_scps = TAILQ_HEAD_INITIALIZER(runnable_scps);
+/* mcp lists. we actually could get by with one list and a TAILQ_CONCAT, but
+ * I'm expecting to want the flexibility of the pointers later. */
+struct proc_list all_mcps_1 = TAILQ_HEAD_INITIALIZER(all_mcps_1);
+struct proc_list all_mcps_2 = TAILQ_HEAD_INITIALIZER(all_mcps_2);
+struct proc_list *primary_mcps = &all_mcps_1;
+struct proc_list *secondary_mcps = &all_mcps_2;
+
+/* Helper, defined below */
+static void __core_request(struct proc *p, uint32_t amt_needed);
+static void add_to_list(struct proc *p, struct proc_list *list);
+static void remove_from_list(struct proc *p, struct proc_list *list);
+static void switch_lists(struct proc *p, struct proc_list *old,
+ struct proc_list *new);
+static void __run_mcp_ksched(void *arg); /* don't call directly */
+static uint32_t get_cores_needed(struct proc *p);
+
+/* Locks / sync tools */
+
+/* poke-style ksched - ensures the MCP ksched only runs once at a time. since
+ * only one mcp ksched runs at a time, while this is set, the ksched knows no
+ * cores are being allocated by other code (though they could be dealloc, due to
+ * yield).
+ *
+ * The main value to this sync method is to make the 'make sure the ksched runs
+ * only once at a time and that it actually runs' invariant/desire wait-free, so
+ * that it can be called anywhere (deep event code, etc).
+ *
+ * As the ksched gets smarter, we'll probably embedd this poker in a bigger
+ * struct that can handle the posting of different types of work. */
+struct poke_tracker ksched_poker = POKE_INITIALIZER(__run_mcp_ksched);
+
+/* this 'big ksched lock' protects a bunch of things, which i may make fine
+ * grained: */
+/* - protects the integrity of proc tailqs/structures, as well as the membership
+ * of a proc on those lists. proc lifetime within the ksched but outside this
+ * lock is protected by the proc kref. */
+//spinlock_t proclist_lock = SPINLOCK_INITIALIZER; /* subsumed by bksl */
+/* - protects the provisioning assignment, and the integrity of all prov
+ * lists (the lists of each proc). */
+//spinlock_t prov_lock = SPINLOCK_INITIALIZER;
+/* - protects allocation structures */
+//spinlock_t alloc_lock = SPINLOCK_INITIALIZER;
+spinlock_t sched_lock = SPINLOCK_INITIALIZER;
+
+/* Alarm struct, for our example 'timer tick' */
+struct alarm_waiter ksched_waiter;
+
+#define TIMER_TICK_USEC 10000 /* 10msec */
+
+/* Helper: Sets up a timer tick on the calling core to go off 10 msec from now.
+ * This assumes the calling core is an LL core, etc. */
+static void set_ksched_alarm(void)
+{
+ set_awaiter_rel(&ksched_waiter, TIMER_TICK_USEC);
+ set_alarm(&per_cpu_info[core_id()].tchain, &ksched_waiter);
+}
-// This could be useful for making scheduling decisions.
-/* Physical coremap: each index is a physical core id, with a proc ptr for
- * whoever *should be or is* running. Very similar to current, which is what
- * process is *really* running there. */
-struct proc *pcoremap[MAX_NUM_CPUS];
+/* RKM alarm, to run the scheduler tick (not in interrupt context) and reset the
+ * alarm. Note that interrupts will be disabled, but this is not the same as
+ * interrupt context. We're a routine kmsg, which means the core is in a
+ * quiescent state. */
+static void __ksched_tick(struct alarm_waiter *waiter)
+{
+ /* TODO: imagine doing some accounting here */
+ run_scheduler();
+ /* Set our alarm to go off, relative to now. This means we might lag a bit,
+ * and our ticks won't match wall clock time. But if we do incremental,
+ * we'll actually punish the next process because the kernel took too long
+ * for the previous process. Ultimately, if we really care, we should
+ * account for the actual time used. */
+ set_awaiter_rel(&ksched_waiter, TIMER_TICK_USEC);
+ set_alarm(&per_cpu_info[core_id()].tchain, &ksched_waiter);
+}
void schedule_init(void)
{
- TAILQ_INIT(&proc_runnablelist);
- return;
+ spin_lock(&sched_lock);
+ assert(!core_id()); /* want the alarm on core0 for now */
+ init_awaiter(&ksched_waiter, __ksched_tick);
+ set_ksched_alarm();
+ corealloc_init();
+ spin_unlock(&sched_lock);
+
+#ifdef CONFIG_ARSC_SERVER
+ /* Most likely we'll have a syscall and a process that dedicates itself to
+ * running this. Or if it's a kthread, we don't need a core. */
+ #error "Find a way to get a core. Probably a syscall to run a server."
+ int arsc_coreid = get_any_idle_core();
+ assert(arsc_coreid >= 0);
+ send_kernel_message(arsc_coreid, arsc_server, 0, 0, 0, KMSG_ROUTINE);
+ printk("Using core %d for the ARSC server\n", arsc_coreid);
+#endif /* CONFIG_ARSC_SERVER */
}
-void schedule_proc(struct proc *p)
+/* Round-robins on whatever list it's on */
+static void add_to_list(struct proc *p, struct proc_list *new)
{
- /* up the refcnt since we are storing the reference */
- kref_get(&p->kref, 1);
- spin_lock_irqsave(&runnablelist_lock);
- printd("Scheduling PID: %d\n", p->pid);
- TAILQ_INSERT_TAIL(&proc_runnablelist, p, proc_link);
- spin_unlock_irqsave(&runnablelist_lock);
- return;
+ assert(!(p->ksched_data.cur_list));
+ TAILQ_INSERT_TAIL(new, p, ksched_data.proc_link);
+ p->ksched_data.cur_list = new;
}
-/* TODO: race here. it's possible that p was already removed from the
- * list (by schedule()), while proc_destroy is trying to remove it from the
- * list. schedule()'s proc_run() won't actually run it (since it's DYING), but
- * this code will probably fuck up. Having TAILQ_REMOVE not hurt will help. */
-void deschedule_proc(struct proc *p)
+static void remove_from_list(struct proc *p, struct proc_list *old)
{
- spin_lock_irqsave(&runnablelist_lock);
- printd("Descheduling PID: %d\n", p->pid);
- TAILQ_REMOVE(&proc_runnablelist, p, proc_link);
- spin_unlock_irqsave(&runnablelist_lock);
- /* down the refcnt, since its no longer stored */
- kref_put(&p->kref);
- return;
+ assert(p->ksched_data.cur_list == old);
+ TAILQ_REMOVE(old, p, ksched_data.proc_link);
+ p->ksched_data.cur_list = 0;
+}
+
+static void switch_lists(struct proc *p, struct proc_list *old,
+ struct proc_list *new)
+{
+ remove_from_list(p, old);
+ add_to_list(p, new);
+}
+
+/* Removes from whatever list p is on */
+static void remove_from_any_list(struct proc *p)
+{
+ if (p->ksched_data.cur_list) {
+ TAILQ_REMOVE(p->ksched_data.cur_list, p, ksched_data.proc_link);
+ p->ksched_data.cur_list = 0;
+ }
+}
+
+/************** Process Management Callbacks **************/
+/* a couple notes:
+ * - the proc lock is NOT held for any of these calls. currently, there is no
+ * lock ordering between the sched lock and the proc lock. since the proc
+ * code doesn't know what we do, it doesn't hold its lock when calling our
+ * CBs.
+ * - since the proc lock isn't held, the proc could be dying, which means we
+ * will receive a __sched_proc_destroy() either before or after some of these
+ * other CBs. the CBs related to list management need to check and abort if
+ * DYING */
+void __sched_proc_register(struct proc *p)
+{
+ assert(!proc_is_dying(p)); /* shouldn't be able to happen yet */
+ /* one ref for the proc's existence, cradle-to-grave */
+ proc_incref(p, 1); /* need at least this OR the 'one for existing' */
+ spin_lock(&sched_lock);
+ corealloc_proc_init(p);
+ add_to_list(p, &unrunnable_scps);
+ spin_unlock(&sched_lock);
+}
+
+/* Returns 0 if it succeeded, an error code otherwise. */
+void __sched_proc_change_to_m(struct proc *p)
+{
+ spin_lock(&sched_lock);
+ /* Need to make sure they aren't dying. if so, we already dealt with their
+ * list membership, etc (or soon will). taking advantage of the 'immutable
+ * state' of dying (so long as refs are held). */
+ if (proc_is_dying(p)) {
+ spin_unlock(&sched_lock);
+ return;
+ }
+ /* Catch user bugs */
+ if (!p->procdata->res_req[RES_CORES].amt_wanted) {
+ printk("[kernel] process needs to specify amt_wanted\n");
+ p->procdata->res_req[RES_CORES].amt_wanted = 1;
+ }
+ /* For now, this should only ever be called on an unrunnable. It's
+ * probably a bug, at this stage in development, to do o/w. */
+ remove_from_list(p, &unrunnable_scps);
+ //remove_from_any_list(p); /* ^^ instead of this */
+ add_to_list(p, primary_mcps);
+ spin_unlock(&sched_lock);
+ //poke_ksched(p, RES_CORES);
+}
+
+/* Sched callback called when the proc dies. pc_arr holds the cores the proc
+ * had, if any, and nr_cores tells us how many are in the array.
+ *
+ * An external, edible ref is passed in. when we return and they decref,
+ * __proc_free will be called (when the last one is done). */
+void __sched_proc_destroy(struct proc *p, uint32_t *pc_arr, uint32_t nr_cores)
+{
+ spin_lock(&sched_lock);
+ /* Unprovision any cores. Note this is different than track_core_dealloc.
+ * The latter does bookkeeping when an allocation changes. This is a
+ * bulk *provisioning* change. */
+ __unprovision_all_cores(p);
+ /* Remove from whatever list we are on (if any - might not be on one if it
+ * was in the middle of __run_mcp_sched) */
+ remove_from_any_list(p);
+ if (nr_cores)
+ __track_core_dealloc_bulk(p, pc_arr, nr_cores);
+ spin_unlock(&sched_lock);
+ /* Drop the cradle-to-the-grave reference, jet-li */
+ proc_decref(p);
+}
+
+/* ksched callbacks. p just woke up and is UNLOCKED. */
+void __sched_mcp_wakeup(struct proc *p)
+{
+ spin_lock(&sched_lock);
+ if (proc_is_dying(p)) {
+ spin_unlock(&sched_lock);
+ return;
+ }
+ /* could try and prioritize p somehow (move it to the front of the list). */
+ spin_unlock(&sched_lock);
+ /* note they could be dying at this point too. */
+ poke(&ksched_poker, p);
+}
+
+/* ksched callbacks. p just woke up and is UNLOCKED. */
+void __sched_scp_wakeup(struct proc *p)
+{
+ spin_lock(&sched_lock);
+ if (proc_is_dying(p)) {
+ spin_unlock(&sched_lock);
+ return;
+ }
+ /* might not be on a list if it is new. o/w, it should be unrunnable */
+ remove_from_any_list(p);
+ add_to_list(p, &runnable_scps);
+ spin_unlock(&sched_lock);
+ /* we could be on a CG core, and all the mgmt cores could be halted. if we
+ * don't tell one of them about the new proc, they will sleep until the
+ * timer tick goes off. */
+ if (!management_core()) {
+ /* TODO: pick a better core and only send if halted.
+ *
+ * ideally, we'd know if a specific mgmt core is sleeping and wake it
+ * up. o/w, we could interrupt an already-running mgmt core that won't
+ * get to our new proc anytime soon. also, by poking core 0, a
+ * different mgmt core could remain idle (and this process would sleep)
+ * until its tick goes off */
+ send_ipi(0, I_POKE_CORE);
+ }
+}
+
+/* Callback to return a core to the ksched, which tracks it as idle and
+ * deallocated from p. The proclock is held (__core_req depends on that).
+ *
+ * This also is a trigger, telling us we have more cores. We could/should make
+ * a scheduling decision (or at least plan to). */
+void __sched_put_idle_core(struct proc *p, uint32_t coreid)
+{
+ spin_lock(&sched_lock);
+ __track_core_dealloc(p, coreid);
+ spin_unlock(&sched_lock);
+}
+
+/* Callback, bulk interface for put_idle. The proclock is held for this. */
+void __sched_put_idle_cores(struct proc *p, uint32_t *pc_arr, uint32_t num)
+{
+ spin_lock(&sched_lock);
+ __track_core_dealloc_bulk(p, pc_arr, num);
+ spin_unlock(&sched_lock);
+ /* could trigger a sched decision here */
}
-/*
- * FIFO - just pop the head from the list and run it.
- * Using irqsave spinlocks for now, since this could be called from a timer
- * interrupt handler (though ought to be in a bottom half or something).
- */
-void schedule(void)
+/* mgmt/LL cores should call this to schedule the calling core and give it to an
+ * SCP. will also prune the dead SCPs from the list. hold the lock before
+ * calling. returns TRUE if it scheduled a proc. */
+static bool __schedule_scp(void)
{
+ // TODO: sort out lock ordering (proc_run_s also locks)
struct proc *p;
-
- spin_lock_irqsave(&runnablelist_lock);
- p = TAILQ_FIRST(&proc_runnablelist);
- if (p) {
- TAILQ_REMOVE(&proc_runnablelist, p, proc_link);
- spin_unlock_irqsave(&runnablelist_lock);
- printd("PID of proc i'm running: %d\n", p->pid);
- /* proc_run will either eat the ref, or we'll decref manually. */
- proc_run(p);
- kref_put(&p->kref);
- } else {
- spin_unlock_irqsave(&runnablelist_lock);
+ uint32_t pcoreid = core_id();
+ struct per_cpu_info *pcpui = &per_cpu_info[pcoreid];
+ /* if there are any runnables, run them here and put any currently running
+ * SCP on the tail of the runnable queue. */
+ if ((p = TAILQ_FIRST(&runnable_scps))) {
+ /* someone is currently running, dequeue them */
+ if (pcpui->owning_proc) {
+ spin_lock(&pcpui->owning_proc->proc_lock);
+ /* process might be dying, with a KMSG to clean it up waiting on
+ * this core. can't do much, so we'll attempt to restart */
+ if (proc_is_dying(pcpui->owning_proc)) {
+ run_as_rkm(run_scheduler);
+ spin_unlock(&pcpui->owning_proc->proc_lock);
+ return FALSE;
+ }
+ printd("Descheduled %d in favor of %d\n", pcpui->owning_proc->pid,
+ p->pid);
+ __proc_set_state(pcpui->owning_proc, PROC_RUNNABLE_S);
+ /* Saving FP state aggressively. Odds are, the SCP was hit by an
+ * IRQ and has a HW ctx, in which case we must save. */
+ __proc_save_fpu_s(pcpui->owning_proc);
+ __proc_save_context_s(pcpui->owning_proc);
+ vcore_account_offline(pcpui->owning_proc, 0);
+ __seq_start_write(&p->procinfo->coremap_seqctr);
+ __unmap_vcore(p, 0);
+ __seq_end_write(&p->procinfo->coremap_seqctr);
+ spin_unlock(&pcpui->owning_proc->proc_lock);
+ /* round-robin the SCPs (inserts at the end of the queue) */
+ switch_lists(pcpui->owning_proc, &unrunnable_scps, &runnable_scps);
+ clear_owning_proc(pcoreid);
+ /* Note we abandon core. It's not strictly necessary. If
+ * we didn't, the TLB would still be loaded with the old
+ * one, til we proc_run_s, and the various paths in
+ * proc_run_s would pick it up. This way is a bit safer for
+ * future changes, but has an extra (empty) TLB flush. */
+ abandon_core();
+ }
+ /* Run the new proc */
+ switch_lists(p, &runnable_scps, &unrunnable_scps);
+ printd("PID of the SCP i'm running: %d\n", p->pid);
+ proc_run_s(p); /* gives it core we're running on */
+ return TRUE;
}
- return;
+ return FALSE;
+}
+
+/* Returns how many new cores p needs. This doesn't lock the proc, so your
+ * answer might be stale. */
+static uint32_t get_cores_needed(struct proc *p)
+{
+ uint32_t amt_wanted, amt_granted;
+ amt_wanted = p->procdata->res_req[RES_CORES].amt_wanted;
+ /* Help them out - if they ask for something impossible, give them 1 so they
+ * can make some progress. (this is racy, and unnecessary). */
+ if (amt_wanted > p->procinfo->max_vcores) {
+ printk("[kernel] proc %d wanted more than max, wanted %d\n", p->pid,
+ amt_wanted);
+ p->procdata->res_req[RES_CORES].amt_wanted = 1;
+ amt_wanted = 1;
+ }
+ /* There are a few cases where amt_wanted is 0, but they are still RUNNABLE
+ * (involving yields, events, and preemptions). In these cases, give them
+ * at least 1, so they can make progress and yield properly. If they are
+ * not WAITING, they did not yield and may have missed a message. */
+ if (!amt_wanted) {
+ /* could ++, but there could be a race and we don't want to give them
+ * more than they ever asked for (in case they haven't prepped) */
+ p->procdata->res_req[RES_CORES].amt_wanted = 1;
+ amt_wanted = 1;
+ }
+ /* amt_granted is racy - they could be *yielding*, but currently they can't
+ * be getting any new cores if the caller is in the mcp_ksched. this is
+ * okay - we won't accidentally give them more cores than they *ever* wanted
+ * (which could crash them), but our answer might be a little stale. */
+ amt_granted = p->procinfo->res_grant[RES_CORES];
+ /* Do not do an assert like this: it could fail (yield in progress): */
+ //assert(amt_granted == p->procinfo->num_vcores);
+ if (amt_wanted <= amt_granted)
+ return 0;
+ return amt_wanted - amt_granted;
+}
+
+/* Actual work of the MCP kscheduler. if we were called by poke_ksched, *arg
+ * might be the process who wanted special service. this would be the case if
+ * we weren't already running the ksched. Sort of a ghetto way to "post work",
+ * such that it's an optimization. */
+static void __run_mcp_ksched(void *arg)
+{
+ struct proc *p, *temp;
+ uint32_t amt_needed;
+ struct proc_list *temp_mcp_list;
+ /* locking to protect the MCP lists' integrity and membership */
+ spin_lock(&sched_lock);
+ /* 2-pass scheme: check each proc on the primary list (FCFS). if they need
+ * nothing, put them on the secondary list. if they need something, rip
+ * them off the list, service them, and if they are still not dying, put
+ * them on the secondary list. We cull the entire primary list, so that
+ * when we start from the beginning each time, we aren't repeatedly checking
+ * procs we looked at on previous waves.
+ *
+ * TODO: we could modify this such that procs that we failed to service move
+ * to yet another list or something. We can also move the WAITINGs to
+ * another list and have wakeup move them back, etc. */
+ while (!TAILQ_EMPTY(primary_mcps)) {
+ TAILQ_FOREACH_SAFE(p, primary_mcps, ksched_data.proc_link, temp) {
+ if (p->state == PROC_WAITING) { /* unlocked peek at the state */
+ switch_lists(p, primary_mcps, secondary_mcps);
+ continue;
+ }
+ amt_needed = get_cores_needed(p);
+ if (!amt_needed) {
+ switch_lists(p, primary_mcps, secondary_mcps);
+ continue;
+ }
+ /* o/w, we want to give cores to this proc */
+ remove_from_list(p, primary_mcps);
+ /* now it won't die, but it could get removed from lists and have
+ * its stuff unprov'd when we unlock */
+ proc_incref(p, 1);
+ /* GIANT WARNING: __core_req will unlock the sched lock for a bit.
+ * It will return with it locked still. We could unlock before we
+ * pass in, but they will relock right away. */
+ // notionally_unlock(&ksched_lock); /* for mouse-eyed viewers */
+ __core_request(p, amt_needed);
+ // notionally_lock(&ksched_lock);
+ /* Peeking at the state is okay, since we hold a ref. Once it is
+ * DYING, it'll remain DYING until we decref. And if there is a
+ * concurrent death, that will spin on the ksched lock (which we
+ * hold, and which protects the proc lists). */
+ if (!proc_is_dying(p))
+ add_to_list(p, secondary_mcps);
+ proc_decref(p); /* fyi, this may trigger __proc_free */
+ /* need to break: the proc lists may have changed when we unlocked
+ * in core_req in ways that the FOREACH_SAFE can't handle. */
+ break;
+ }
+ }
+ /* at this point, we moved all the procs over to the secondary list, and
+ * attempted to service the ones that wanted something. now just swap the
+ * lists for the next invocation of the ksched. */
+ temp_mcp_list = primary_mcps;
+ primary_mcps = secondary_mcps;
+ secondary_mcps = temp_mcp_list;
+ spin_unlock(&sched_lock);
+}
+
+/* Something has changed, and for whatever reason the scheduler should
+ * reevaluate things.
+ *
+ * Don't call this if you are processing a syscall or otherwise care about your
+ * kthread variables, cur_proc/owning_proc, etc.
+ *
+ * Don't call this from interrupt context (grabs proclocks). */
+void run_scheduler(void)
+{
+ /* MCP scheduling: post work, then poke. for now, i just want the func to
+ * run again, so merely a poke is sufficient. */
+ poke(&ksched_poker, 0);
+ if (management_core()) {
+ spin_lock(&sched_lock);
+ __schedule_scp();
+ spin_unlock(&sched_lock);
+ }
+}
+
+/* A process is asking the ksched to look at its resource desires. The
+ * scheduler is free to ignore this, for its own reasons, so long as it
+ * eventually gets around to looking at resource desires. */
+void poke_ksched(struct proc *p, unsigned int res_type)
+{
+ /* ignoring res_type for now. could post that if we wanted (would need some
+ * other structs/flags) */
+ if (!__proc_is_mcp(p))
+ return;
+ poke(&ksched_poker, p);
+}
+
+/* The calling cpu/core has nothing to do and plans to idle/halt. This is an
+ * opportunity to pick the nature of that halting (low power state, etc), or
+ * provide some other work (_Ss on LL cores). Note that interrupts are
+ * disabled, and if you return, the core will cpu_halt(). */
+void cpu_bored(void)
+{
+ bool new_proc = FALSE;
+ if (!management_core())
+ return;
+ spin_lock(&sched_lock);
+ new_proc = __schedule_scp();
+ spin_unlock(&sched_lock);
+ /* if we just scheduled a proc, we need to manually restart it, instead of
+ * returning. if we return, the core will halt. */
+ if (new_proc) {
+ proc_restartcore();
+ assert(0);
+ }
+ /* Could drop into the monitor if there are no processes at all. For now,
+ * the 'call of the giraffe' suffices. */
+}
+
+/* Available resources changed (plus or minus). Some parts of the kernel may
+ * call this if a particular resource that is 'quantity-based' changes. Things
+ * like available RAM to processes, bandwidth, etc. Cores would probably be
+ * inappropriate, since we need to know which specific core is now free. */
+void avail_res_changed(int res_type, long change)
+{
+ printk("[kernel] ksched doesn't track any resources yet!\n");
+}
+
+/* This deals with a request for more cores. The amt of new cores needed is
+ * passed in. The ksched lock is held, but we are free to unlock if we want
+ * (and we must, if calling out of the ksched to anything high-level).
+ *
+ * Side note: if we want to warn, then we can't deal with this proc's prov'd
+ * cores until we wait til the alarm goes off. would need to put all
+ * alarmed cores on a list and wait til the alarm goes off to do the full
+ * preempt. and when those cores come in voluntarily, we'd need to know to
+ * give them to this proc. */
+static void __core_request(struct proc *p, uint32_t amt_needed)
+{
+ uint32_t nr_to_grant = 0;
+ uint32_t corelist[num_cores];
+ uint32_t pcoreid;
+ struct proc *proc_to_preempt;
+ bool success;
+ /* we come in holding the ksched lock, and we hold it here to protect
+ * allocations and provisioning. */
+ /* get all available cores from their prov_not_alloc list. the list might
+ * change when we unlock (new cores added to it, or the entire list emptied,
+ * but no core allocations will happen (we hold the poke)). */
+ while (nr_to_grant != amt_needed) {
+ /* Find the next best core to allocate to p. It may be a core
+ * provisioned to p, and it might not be. */
+ pcoreid = __find_best_core_to_alloc(p);
+ /* If no core is returned, we know that there are no more cores to give
+ * out, so we exit the loop. */
+ if (pcoreid == -1)
+ break;
+ /* If the pcore chosen currently has a proc allocated to it, we know
+ * it must be provisioned to p, but not allocated to it. We need to try
+ * to preempt. After this block, the core will be track_dealloc'd and
+ * on the idle list (regardless of whether we had to preempt or not) */
+ if (get_alloc_proc(pcoreid)) {
+ proc_to_preempt = get_alloc_proc(pcoreid);
+ /* would break both preemption and maybe the later decref */
+ assert(proc_to_preempt != p);
+ /* need to keep a valid, external ref when we unlock */
+ proc_incref(proc_to_preempt, 1);
+ spin_unlock(&sched_lock);
+ /* sending no warning time for now - just an immediate preempt. */
+ success = proc_preempt_core(proc_to_preempt, pcoreid, 0);
+ /* reaquire locks to protect provisioning and idle lists */
+ spin_lock(&sched_lock);
+ if (success) {
+ /* we preempted it before the proc could yield or die.
+ * alloc_proc should not have changed (it'll change in death and
+ * idle CBs). the core is not on the idle core list. (if we
+ * ever have proc alloc lists, it'll still be on the old proc's
+ * list). */
+ assert(get_alloc_proc(pcoreid));
+ /* regardless of whether or not it is still prov to p, we need
+ * to note its dealloc. we are doing some excessive checking of
+ * p == prov_proc, but using this helper is a lot clearer. */
+ __track_core_dealloc(proc_to_preempt, pcoreid);
+ } else {
+ /* the preempt failed, which should only happen if the pcore was
+ * unmapped (could be dying, could be yielding, but NOT
+ * preempted). whoever unmapped it also triggered (or will soon
+ * trigger) a track_core_dealloc and put it on the idle list.
+ * Our signal for this is get_alloc_proc() being 0. We need to
+ * spin and let whoever is trying to free the core grab the
+ * ksched lock. We could use an 'ignore_next_idle' flag per
+ * sched_pcore, but it's not critical anymore.
+ *
+ * Note, we're relying on us being the only preemptor - if the
+ * core was unmapped by *another* preemptor, there would be no
+ * way of knowing the core was made idle *yet* (the success
+ * branch in another thread). likewise, if there were another
+ * allocator, the pcore could have been put on the idle list and
+ * then quickly removed/allocated. */
+ cmb();
+ while (get_alloc_proc(pcoreid)) {
+ /* this loop should be very rare */
+ spin_unlock(&sched_lock);
+ udelay(1);
+ spin_lock(&sched_lock);
+ }
+ }
+ /* no longer need to keep p_to_pre alive */
+ proc_decref(proc_to_preempt);
+ /* might not be prov to p anymore (rare race). pcoreid is idle - we
+ * might get it later, or maybe we'll give it to its rightful proc*/
+ if (get_prov_proc(pcoreid) != p)
+ continue;
+ }
+ /* At this point, the pcore is idle, regardless of how we got here
+ * (successful preempt, failed preempt, or it was idle in the first
+ * place). We also know the core is still provisioned to us. Lets add
+ * it to the corelist for p (so we can give it to p in bulk later), and
+ * track its allocation with p (so our internal data structures stay in
+ * sync). We rely on the fact that we are the only allocator (pcoreid is
+ * still idle, despite (potentially) unlocking during the preempt
+ * attempt above). It is guaranteed to be track_dealloc'd()
+ * (regardless of how we got here). */
+ corelist[nr_to_grant] = pcoreid;
+ nr_to_grant++;
+ __track_core_alloc(p, pcoreid);
+ }
+ /* Now, actually give them out */
+ if (nr_to_grant) {
+ /* Need to unlock before calling out to proc code. We are somewhat
+ * relying on being the only one allocating 'thread' here, since another
+ * allocator could have seen these cores (if they are prov to some proc)
+ * and could be trying to give them out (and assuming they are already
+ * on the idle list). */
+ spin_unlock(&sched_lock);
+ /* give them the cores. this will start up the extras if RUNNING_M. */
+ spin_lock(&p->proc_lock);
+ /* if they fail, it is because they are WAITING or DYING. we could give
+ * the cores to another proc or whatever. for the current type of
+ * ksched, we'll just put them back on the pile and return. Note, the
+ * ksched could check the states after locking, but it isn't necessary:
+ * just need to check at some point in the ksched loop. */
+ if (__proc_give_cores(p, corelist, nr_to_grant)) {
+ spin_unlock(&p->proc_lock);
+ /* we failed, put the cores and track their dealloc. lock is
+ * protecting those structures. */
+ spin_lock(&sched_lock);
+ __track_core_dealloc_bulk(p, corelist, nr_to_grant);
+ } else {
+ /* at some point after giving cores, call proc_run_m() (harmless on
+ * RUNNING_Ms). You can give small groups of cores, then run them
+ * (which is more efficient than interleaving runs with the gives
+ * for bulk preempted processes). */
+ __proc_run_m(p);
+ spin_unlock(&p->proc_lock);
+ /* main mcp_ksched wants this held (it came to __core_req held) */
+ spin_lock(&sched_lock);
+ }
+ }
+ /* note the ksched lock is still held */
+}
+
+/* Provision a core to a process. This function wraps the primary logic
+ * implemented in __provision_core, with a lock, error checking, etc. */
+int provision_core(struct proc *p, uint32_t pcoreid)
+{
+ /* Make sure we aren't asking for something that doesn't exist (bounds check
+ * on the pcore array) */
+ if (!(pcoreid < num_cores)) {
+ set_errno(ENXIO);
+ return -1;
+ }
+ /* Don't allow the provisioning of LL cores */
+ if (is_ll_core(pcoreid)) {
+ set_errno(EBUSY);
+ return -1;
+ }
+ /* Note the sched lock protects the tailqs for all procs in this code.
+ * If we need a finer grained sched lock, this is one place where we could
+ * have a different lock */
+ spin_lock(&sched_lock);
+ __provision_core(p, pcoreid);
+ spin_unlock(&sched_lock);
+ return 0;
}
-void dump_proclist(struct proc_list *list)
+/************** Debugging **************/
+void sched_diag(void)
{
struct proc *p;
- TAILQ_FOREACH(p, list, proc_link)
- printk("PID: %d\n", p->pid);
+ spin_lock(&sched_lock);
+ TAILQ_FOREACH(p, &runnable_scps, ksched_data.proc_link)
+ printk("Runnable _S PID: %d\n", p->pid);
+ TAILQ_FOREACH(p, &unrunnable_scps, ksched_data.proc_link)
+ printk("Unrunnable _S PID: %d\n", p->pid);
+ TAILQ_FOREACH(p, primary_mcps, ksched_data.proc_link)
+ printk("Primary MCP PID: %d\n", p->pid);
+ TAILQ_FOREACH(p, secondary_mcps, ksched_data.proc_link)
+ printk("Secondary MCP PID: %d\n", p->pid);
+ spin_unlock(&sched_lock);
return;
}
+
+void print_resources(struct proc *p)
+{
+ printk("--------------------\n");
+ printk("PID: %d\n", p->pid);
+ printk("--------------------\n");
+ for (int i = 0; i < MAX_NUM_RESOURCES; i++)
+ printk("Res type: %02d, amt wanted: %08d, amt granted: %08d\n", i,
+ p->procdata->res_req[i].amt_wanted, p->procinfo->res_grant[i]);
+}
+
+void print_all_resources(void)
+{
+ /* Hash helper */
+ void __print_resources(void *item, void *opaque)
+ {
+ print_resources((struct proc*)item);
+ }
+ spin_lock(&pid_hash_lock);
+ hash_for_each(pid_hash, __print_resources, NULL);
+ spin_unlock(&pid_hash_lock);
+}
+
+void next_core_to_alloc(uint32_t pcoreid)
+{
+ spin_lock(&sched_lock);
+ __next_core_to_alloc(pcoreid);
+ spin_unlock(&sched_lock);
+}
+
+void sort_idle_cores(void)
+{
+ spin_lock(&sched_lock);
+ __sort_idle_cores();
+ spin_unlock(&sched_lock);
+}
projects / akaros.git / blobdiff