diff options
Diffstat (limited to 'migration/postcopy-ram.c')
| -rw-r--r-- | migration/postcopy-ram.c | 575 |
1 files changed, 449 insertions, 126 deletions
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 5d3edfc..45af9a3 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -31,7 +31,7 @@ #include "qemu/error-report.h" #include "trace.h" #include "hw/boards.h" -#include "exec/ramblock.h" +#include "system/ramblock.h" #include "socket.h" #include "yank_functions.h" #include "tls.h" @@ -90,10 +90,10 @@ void postcopy_thread_create(MigrationIncomingState *mis, QemuThread *thread, const char *name, void *(*fn)(void *), int joinable) { - qemu_sem_init(&mis->thread_sync_sem, 0); + qemu_event_init(&mis->thread_sync_event, false); qemu_thread_create(thread, name, fn, mis, joinable); - qemu_sem_wait(&mis->thread_sync_sem); - qemu_sem_destroy(&mis->thread_sync_sem); + qemu_event_wait(&mis->thread_sync_event); + qemu_event_destroy(&mis->thread_sync_event); } /* Postcopy needs to detect accesses to pages that haven't yet been copied @@ -110,19 +110,104 @@ void postcopy_thread_create(MigrationIncomingState *mis, #include <sys/eventfd.h> #include <linux/userfaultfd.h> +/* + * Here we use 24 buckets, which means the last bucket will cover [2^24 us, + * 2^25 us) ~= [16, 32) seconds. It should be far enough to record even + * extreme (perf-wise broken) 1G pages moving over, which can sometimes + * take a few seconds due to various reasons. Anything more than that + * might be unsensible to account anymore. + */ +#define BLOCKTIME_LATENCY_BUCKET_N (24) + +/* All the time records are in unit of nanoseconds */ typedef struct PostcopyBlocktimeContext { - /* time when page fault initiated per vCPU */ - uint32_t *page_fault_vcpu_time; - /* page address per vCPU */ - uintptr_t *vcpu_addr; - uint32_t total_blocktime; /* blocktime per vCPU */ - uint32_t *vcpu_blocktime; + uint64_t *vcpu_blocktime_total; + /* count of faults per vCPU */ + uint64_t *vcpu_faults_count; + /* + * count of currently blocked faults per vCPU. + * + * NOTE: Normally there should only be one fault in-progress per vCPU + * thread, so logically it _seems_ vcpu_faults_count[] for any vCPU + * should be either zero or one. However, there can be reasons we see + * >1 faults on the same vCPU thread. + * + * CASE (1): since the process to resolve faults (ioctl(UFFDIO_COPY), + * for example) is done before taking the mutex that protects the + * blocktime context, it can happen that we read more than one faulted + * addresses per vCPU. + * + * One example when we can see >1 faulted addresses for one vCPU: + * + * vcpu1 thread fault thread resolve thread + * ============ ============ ============== + * + * faulted on addr1 + * read uffd msg (addr1) + * MUTEX_LOCK + * add entry (cpu1, addr1) + * MUTEX_UNLOCK + * request remote fault (addr1) + * resolve fault (addr1) + * addr1 resolved, continue.. + * faulted on addr2 + * read uffd msg (addr2) + * MUTEX_LOCK + * add entry (cpu1, addr2) <--------------- [A] + * MUTEX_UNLOCK + * MUTEX_LOCK + * remove entry (cpu1, addr1) + * MUTEX_UNLOCK + * + * In above case, we may see (cpu1, addr1) and (cpu1, addr2) entries to + * appear together at [A], when it gets the lock before the resolve + * thread. Use this counter to maintain such case, and only when it + * reaches zero we know the vCPU is not blocked anymore. + * + * CASE (2): theoretically (the author admit to not have verified + * this..), one vCPU thread can also generate more than one userfaultfd + * message on the same address. It can happen e.g. for whatever reason + * the fault got retried before a resolution arrives. In that extremely + * rare case, we could also see two (cpu1, addr1) entries. + * + * In all cases, be prepared with such re-entrancies with this array. + * + * Using uint8_t should be far enough for now. For example, when + * there're only one resolve thread (postcopy ram listening thread), + * the max (concurrent fault entries) should be two. + */ + uint8_t *vcpu_faults_current; + /* + * The hash that contains addr1->[(cpu1,ts1),(cpu2,ts2) ...] mappings. + * Each of the entry is a tuple of (CPU index, fault timestamp) showing + * that a fault was requested. + */ + GHashTable *vcpu_addr_hash; + /* + * Each bucket stores the count of faults that were resolved within the + * bucket window [2^N us, 2^(N+1) us). + */ + uint64_t latency_buckets[BLOCKTIME_LATENCY_BUCKET_N]; + /* total blocktime when all vCPUs are stopped */ + uint64_t total_blocktime; /* point in time when last page fault was initiated */ - uint32_t last_begin; + uint64_t last_begin; /* number of vCPU are suspended */ int smp_cpus_down; - uint64_t start_time; + + /* + * Fast path for looking up vcpu_index from tid. NOTE: this result + * only reflects the vcpu setup when postcopy is running. It may not + * always match with the current vcpu setup because vcpus can be hot + * attached/detached after migration completes. However this should be + * stable when blocktime is using the structure. + */ + GHashTable *tid_to_vcpu_hash; + /* Count of non-vCPU faults. This is only for debugging purpose. */ + uint64_t non_vcpu_faults; + /* total blocktime when a non-vCPU thread is stopped */ + uint64_t non_vcpu_blocktime_total; /* * Handler for exit event, necessary for @@ -131,11 +216,41 @@ typedef struct PostcopyBlocktimeContext { Notifier exit_notifier; } PostcopyBlocktimeContext; +typedef struct { + /* The time the fault was triggered */ + uint64_t fault_time; + /* + * The vCPU index that was blocked, when cpu==-1, it means it's a + * fault from non-vCPU threads. + */ + int cpu; +} BlocktimeVCPUEntry; + +/* Alloc an entry to record a vCPU fault */ +static BlocktimeVCPUEntry * +blocktime_vcpu_entry_alloc(int cpu, uint64_t fault_time) +{ + BlocktimeVCPUEntry *entry = g_new(BlocktimeVCPUEntry, 1); + + entry->fault_time = fault_time; + entry->cpu = cpu; + + return entry; +} + +/* Free a @GList of @BlocktimeVCPUEntry */ +static void blocktime_vcpu_list_free(gpointer data) +{ + g_list_free_full(data, g_free); +} + static void destroy_blocktime_context(struct PostcopyBlocktimeContext *ctx) { - g_free(ctx->page_fault_vcpu_time); - g_free(ctx->vcpu_addr); - g_free(ctx->vcpu_blocktime); + g_hash_table_destroy(ctx->tid_to_vcpu_hash); + g_hash_table_destroy(ctx->vcpu_addr_hash); + g_free(ctx->vcpu_blocktime_total); + g_free(ctx->vcpu_faults_count); + g_free(ctx->vcpu_faults_current); g_free(ctx); } @@ -146,32 +261,65 @@ static void migration_exit_cb(Notifier *n, void *data) destroy_blocktime_context(ctx); } +static GHashTable *blocktime_init_tid_to_vcpu_hash(void) +{ + /* + * TID as an unsigned int can be directly used as the key. However, + * CPU index can NOT be directly used as value, because CPU index can + * be 0, which means NULL. Then when lookup we can never know whether + * it's 0 or "not found". Hence use an indirection for CPU index. + */ + GHashTable *table = g_hash_table_new_full(g_direct_hash, g_direct_equal, + NULL, g_free); + CPUState *cpu; + + /* + * Initialize the tid->cpu_id mapping for lookups. The caller needs to + * make sure when reaching here the CPU topology is frozen and will be + * stable for the whole blocktime trapping period. + */ + CPU_FOREACH(cpu) { + int *value = g_new(int, 1); + + *value = cpu->cpu_index; + g_hash_table_insert(table, + GUINT_TO_POINTER((uint32_t)cpu->thread_id), + value); + trace_postcopy_blocktime_tid_cpu_map(cpu->cpu_index, cpu->thread_id); + } + + return table; +} + static struct PostcopyBlocktimeContext *blocktime_context_new(void) { MachineState *ms = MACHINE(qdev_get_machine()); unsigned int smp_cpus = ms->smp.cpus; PostcopyBlocktimeContext *ctx = g_new0(PostcopyBlocktimeContext, 1); - ctx->page_fault_vcpu_time = g_new0(uint32_t, smp_cpus); - ctx->vcpu_addr = g_new0(uintptr_t, smp_cpus); - ctx->vcpu_blocktime = g_new0(uint32_t, smp_cpus); - ctx->exit_notifier.notify = migration_exit_cb; - ctx->start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); - qemu_add_exit_notifier(&ctx->exit_notifier); - return ctx; -} + /* Initialize all counters to be zeros */ + memset(ctx->latency_buckets, 0, sizeof(ctx->latency_buckets)); -static uint32List *get_vcpu_blocktime_list(PostcopyBlocktimeContext *ctx) -{ - MachineState *ms = MACHINE(qdev_get_machine()); - uint32List *list = NULL; - int i; + ctx->vcpu_blocktime_total = g_new0(uint64_t, smp_cpus); + ctx->vcpu_faults_count = g_new0(uint64_t, smp_cpus); + ctx->vcpu_faults_current = g_new0(uint8_t, smp_cpus); + ctx->tid_to_vcpu_hash = blocktime_init_tid_to_vcpu_hash(); - for (i = ms->smp.cpus - 1; i >= 0; i--) { - QAPI_LIST_PREPEND(list, ctx->vcpu_blocktime[i]); - } + /* + * The key (host virtual addresses) will always be gpointer-sized on + * either 32bits or 64bits systems, so it'll fit as a direct key. + * + * The value will be a list of BlocktimeVCPUEntry entries. + */ + ctx->vcpu_addr_hash = g_hash_table_new_full(g_direct_hash, + g_direct_equal, + NULL, + blocktime_vcpu_list_free); + + ctx->exit_notifier.notify = migration_exit_cb; + qemu_add_exit_notifier(&ctx->exit_notifier); - return list; + return ctx; } /* @@ -185,18 +333,64 @@ void fill_destination_postcopy_migration_info(MigrationInfo *info) { MigrationIncomingState *mis = migration_incoming_get_current(); PostcopyBlocktimeContext *bc = mis->blocktime_ctx; + MachineState *ms = MACHINE(qdev_get_machine()); + uint64_t latency_total = 0, faults = 0; + uint32List *list_blocktime = NULL; + uint64List *list_latency = NULL; + uint64List *latency_buckets = NULL; + int i; if (!bc) { return; } + for (i = ms->smp.cpus - 1; i >= 0; i--) { + uint64_t latency, total, count; + + /* Convert ns -> ms */ + QAPI_LIST_PREPEND(list_blocktime, + (uint32_t)(bc->vcpu_blocktime_total[i] / SCALE_MS)); + + /* The rest in nanoseconds */ + total = bc->vcpu_blocktime_total[i]; + latency_total += total; + count = bc->vcpu_faults_count[i]; + faults += count; + + if (count) { + latency = total / count; + } else { + /* No fault detected */ + latency = 0; + } + + QAPI_LIST_PREPEND(list_latency, latency); + } + + for (i = BLOCKTIME_LATENCY_BUCKET_N - 1; i >= 0; i--) { + QAPI_LIST_PREPEND(latency_buckets, bc->latency_buckets[i]); + } + + latency_total += bc->non_vcpu_blocktime_total; + faults += bc->non_vcpu_faults; + + info->has_postcopy_non_vcpu_latency = true; + info->postcopy_non_vcpu_latency = bc->non_vcpu_faults ? + (bc->non_vcpu_blocktime_total / bc->non_vcpu_faults) : 0; info->has_postcopy_blocktime = true; - info->postcopy_blocktime = bc->total_blocktime; + /* Convert ns -> ms */ + info->postcopy_blocktime = (uint32_t)(bc->total_blocktime / SCALE_MS); info->has_postcopy_vcpu_blocktime = true; - info->postcopy_vcpu_blocktime = get_vcpu_blocktime_list(bc); + info->postcopy_vcpu_blocktime = list_blocktime; + info->has_postcopy_latency = true; + info->postcopy_latency = faults ? (latency_total / faults) : 0; + info->has_postcopy_vcpu_latency = true; + info->postcopy_vcpu_latency = list_latency; + info->has_postcopy_latency_dist = true; + info->postcopy_latency_dist = latency_buckets; } -static uint32_t get_postcopy_total_blocktime(void) +static uint64_t get_postcopy_total_blocktime(void) { MigrationIncomingState *mis = migration_incoming_get_current(); PostcopyBlocktimeContext *bc = mis->blocktime_ctx; @@ -300,13 +494,13 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis, } #ifdef UFFD_FEATURE_THREAD_ID + /* + * Postcopy blocktime conditionally needs THREAD_ID feature (introduced + * to Linux in 2017). Always try to enable it when QEMU is compiled + * with such environment. + */ if (UFFD_FEATURE_THREAD_ID & supported_features) { asked_features |= UFFD_FEATURE_THREAD_ID; - if (migrate_postcopy_blocktime()) { - if (!mis->blocktime_ctx) { - mis->blocktime_ctx = blocktime_context_new(); - } - } } #endif @@ -752,8 +946,12 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, pagesize); } +/* + * NOTE: @tid is only used when postcopy-blocktime feature is enabled, and + * also optional: when zero is provided, the fault accounting will be ignored. + */ static int postcopy_request_page(MigrationIncomingState *mis, RAMBlock *rb, - ram_addr_t start, uint64_t haddr) + ram_addr_t start, uint64_t haddr, uint32_t tid) { void *aligned = (void *)(uintptr_t)ROUND_DOWN(haddr, qemu_ram_pagesize(rb)); @@ -772,7 +970,7 @@ static int postcopy_request_page(MigrationIncomingState *mis, RAMBlock *rb, return received ? 0 : postcopy_place_page_zero(mis, aligned, rb); } - return migrate_send_rp_req_pages(mis, rb, start, haddr); + return migrate_send_rp_req_pages(mis, rb, start, haddr, tid); } /* @@ -793,83 +991,204 @@ int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, qemu_ram_get_idstr(rb), rb_offset); return postcopy_wake_shared(pcfd, client_addr, rb); } - postcopy_request_page(mis, rb, aligned_rbo, client_addr); + /* TODO: support blocktime tracking */ + postcopy_request_page(mis, rb, aligned_rbo, client_addr, 0); return 0; } -static int get_mem_fault_cpu_index(uint32_t pid) +static int blocktime_get_vcpu(PostcopyBlocktimeContext *ctx, uint32_t tid) { - CPUState *cpu_iter; + int *found; - CPU_FOREACH(cpu_iter) { - if (cpu_iter->thread_id == pid) { - trace_get_mem_fault_cpu_index(cpu_iter->cpu_index, pid); - return cpu_iter->cpu_index; - } + found = g_hash_table_lookup(ctx->tid_to_vcpu_hash, GUINT_TO_POINTER(tid)); + if (!found) { + /* + * NOTE: this is possible, because QEMU's non-vCPU threads can + * also access a missing page. Or, when KVM async pf is enabled, a + * fault can even happen from a kworker.. + */ + return -1; } - trace_get_mem_fault_cpu_index(-1, pid); - return -1; + + return *found; } -static uint32_t get_low_time_offset(PostcopyBlocktimeContext *dc) +static uint64_t get_current_ns(void) { - int64_t start_time_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - - dc->start_time; - return start_time_offset < 1 ? 1 : start_time_offset & UINT32_MAX; + return (uint64_t)qemu_clock_get_ns(QEMU_CLOCK_REALTIME); +} + +/* + * Inject an (cpu, fault_time) entry into the database, using addr as key. + * When cpu==-1, it means it's a non-vCPU fault. + */ +static void blocktime_fault_inject(PostcopyBlocktimeContext *ctx, + uintptr_t addr, int cpu, uint64_t time) +{ + BlocktimeVCPUEntry *entry = blocktime_vcpu_entry_alloc(cpu, time); + GHashTable *table = ctx->vcpu_addr_hash; + gpointer key = (gpointer)addr; + GList *head, *list; + gboolean result; + + head = g_hash_table_lookup(table, key); + if (head) { + /* + * If existed, steal the @head for list operation rather than + * freeing it, making sure steal succeeded. + */ + result = g_hash_table_steal(table, key); + assert(result == TRUE); + } + + /* + * Now the key is guaranteed to be absent. Two cases: + * + * (1) There's no existing entry, list contains the only one. Insert. + * (2) There're existing entries, after stealing we own it, prepend the + * result and re-insert. + */ + list = g_list_prepend(head, entry); + g_hash_table_insert(table, key, list); + + trace_postcopy_blocktime_begin(addr, time, cpu, !!head); } /* - * This function is being called when pagefault occurs. It - * tracks down vCPU blocking time. + * This function is being called when pagefault occurs. It tracks down vCPU + * blocking time. It's protected by @page_request_mutex. * * @addr: faulted host virtual address * @ptid: faulted process thread id * @rb: ramblock appropriate to addr */ -static void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid, - RAMBlock *rb) +void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid, + RAMBlock *rb) { - int cpu, already_received; + int cpu; MigrationIncomingState *mis = migration_incoming_get_current(); PostcopyBlocktimeContext *dc = mis->blocktime_ctx; - uint32_t low_time_offset; + uint64_t current; if (!dc || ptid == 0) { return; } - cpu = get_mem_fault_cpu_index(ptid); - if (cpu < 0) { - return; + + /* + * The caller should only inject a blocktime entry when the page is + * yet missing. + */ + assert(!ramblock_recv_bitmap_test(rb, (void *)addr)); + + current = get_current_ns(); + cpu = blocktime_get_vcpu(dc, ptid); + + if (cpu >= 0) { + /* How many faults on this vCPU in total? */ + dc->vcpu_faults_count[cpu]++; + + /* + * Account how many concurrent faults on this vCPU we trapped. See + * comments above vcpu_faults_current[] on why it can be more than one. + */ + if (dc->vcpu_faults_current[cpu]++ == 0) { + dc->smp_cpus_down++; + /* + * We use last_begin to cover (1) the 1st fault on this specific + * vCPU, but meanwhile (2) the last vCPU that got blocked. It's + * only used to calculate system-wide blocktime. + */ + dc->last_begin = current; + } + + /* Making sure it won't overflow - it really should never! */ + assert(dc->vcpu_faults_current[cpu] <= 255); + } else { + /* + * For non-vCPU thread faults, we don't care about tid or cpu index + * or time the thread is blocked (e.g., a kworker trying to help + * KVM when async_pf=on is OK to be blocked and not affect guest + * responsiveness), but we care about latency. Track it with + * cpu=-1. + * + * Note that this will NOT affect blocktime reports on vCPU being + * blocked, but only about system-wide latency reports. + */ + dc->non_vcpu_faults++; } - low_time_offset = get_low_time_offset(dc); - if (dc->vcpu_addr[cpu] == 0) { - qatomic_inc(&dc->smp_cpus_down); + blocktime_fault_inject(dc, addr, cpu, current); +} + +static void blocktime_latency_account(PostcopyBlocktimeContext *ctx, + uint64_t time_us) +{ + /* + * Convert time (in us) to bucket index it belongs. Take extra caution + * of time_us==0 even if normally rare - when happens put into bucket 0. + */ + int index = time_us ? (63 - clz64(time_us)) : 0; + + assert(index >= 0); + + /* If it's too large, put into top bucket */ + if (index >= BLOCKTIME_LATENCY_BUCKET_N) { + index = BLOCKTIME_LATENCY_BUCKET_N - 1; } - qatomic_xchg(&dc->last_begin, low_time_offset); - qatomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset); - qatomic_xchg(&dc->vcpu_addr[cpu], addr); + ctx->latency_buckets[index]++; +} + +typedef struct { + PostcopyBlocktimeContext *ctx; + uint64_t current; + int affected_cpus; + int affected_non_cpus; +} BlockTimeVCPUIter; + +static void blocktime_cpu_list_iter_fn(gpointer data, gpointer user_data) +{ + BlockTimeVCPUIter *iter = user_data; + PostcopyBlocktimeContext *ctx = iter->ctx; + BlocktimeVCPUEntry *entry = data; + uint64_t time_passed; + int cpu = entry->cpu; /* - * check it here, not at the beginning of the function, - * due to, check could occur early than bitmap_set in - * qemu_ufd_copy_ioctl + * Time should never go back.. so when the fault is resolved it must be + * later than when it was faulted. */ - already_received = ramblock_recv_bitmap_test(rb, (void *)addr); - if (already_received) { - qatomic_xchg(&dc->vcpu_addr[cpu], 0); - qatomic_xchg(&dc->page_fault_vcpu_time[cpu], 0); - qatomic_dec(&dc->smp_cpus_down); + assert(iter->current >= entry->fault_time); + time_passed = iter->current - entry->fault_time; + + /* Latency buckets are in microseconds */ + blocktime_latency_account(ctx, time_passed / SCALE_US); + + if (cpu >= 0) { + /* + * If we resolved all pending faults on one vCPU due to this page + * resolution, take a note. + */ + if (--ctx->vcpu_faults_current[cpu] == 0) { + ctx->vcpu_blocktime_total[cpu] += time_passed; + iter->affected_cpus += 1; + } + trace_postcopy_blocktime_end_one(cpu, ctx->vcpu_faults_current[cpu]); + } else { + iter->affected_non_cpus++; + ctx->non_vcpu_blocktime_total += time_passed; + /* + * We do not maintain how many pending non-vCPU faults because we + * do not care about blocktime, only latency. + */ + trace_postcopy_blocktime_end_one(-1, 0); } - trace_mark_postcopy_blocktime_begin(addr, dc, dc->page_fault_vcpu_time[cpu], - cpu, already_received); } /* - * This function just provide calculated blocktime per cpu and trace it. - * Total blocktime is calculated in mark_postcopy_blocktime_end. - * + * This function just provide calculated blocktime per cpu and trace it. + * Total blocktime is calculated in mark_postcopy_blocktime_end. It's + * protected by @page_request_mutex. * * Assume we have 3 CPU * @@ -899,48 +1218,45 @@ static void mark_postcopy_blocktime_end(uintptr_t addr) PostcopyBlocktimeContext *dc = mis->blocktime_ctx; MachineState *ms = MACHINE(qdev_get_machine()); unsigned int smp_cpus = ms->smp.cpus; - int i, affected_cpu = 0; - bool vcpu_total_blocktime = false; - uint32_t read_vcpu_time, low_time_offset; + BlockTimeVCPUIter iter = { + .current = get_current_ns(), + .affected_cpus = 0, + .affected_non_cpus = 0, + .ctx = dc, + }; + gpointer key = (gpointer)addr; + GHashTable *table; + GList *list; if (!dc) { return; } - low_time_offset = get_low_time_offset(dc); - /* lookup cpu, to clear it, - * that algorithm looks straightforward, but it's not - * optimal, more optimal algorithm is keeping tree or hash - * where key is address value is a list of */ - for (i = 0; i < smp_cpus; i++) { - uint32_t vcpu_blocktime = 0; - - read_vcpu_time = qatomic_fetch_add(&dc->page_fault_vcpu_time[i], 0); - if (qatomic_fetch_add(&dc->vcpu_addr[i], 0) != addr || - read_vcpu_time == 0) { - continue; - } - qatomic_xchg(&dc->vcpu_addr[i], 0); - vcpu_blocktime = low_time_offset - read_vcpu_time; - affected_cpu += 1; - /* we need to know is that mark_postcopy_end was due to - * faulted page, another possible case it's prefetched - * page and in that case we shouldn't be here */ - if (!vcpu_total_blocktime && - qatomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) { - vcpu_total_blocktime = true; - } - /* continue cycle, due to one page could affect several vCPUs */ - dc->vcpu_blocktime[i] += vcpu_blocktime; + table = dc->vcpu_addr_hash; + /* the address wasn't tracked at all? */ + list = g_hash_table_lookup(table, key); + if (!list) { + return; } - qatomic_sub(&dc->smp_cpus_down, affected_cpu); - if (vcpu_total_blocktime) { - dc->total_blocktime += low_time_offset - qatomic_fetch_add( - &dc->last_begin, 0); + /* + * Loop over the set of vCPUs that got blocked on this addr, do the + * blocktime accounting. After that, remove the whole list. + */ + g_list_foreach(list, blocktime_cpu_list_iter_fn, &iter); + g_hash_table_remove(table, key); + + /* + * If all vCPUs used to be down, and copying this page would free some + * vCPUs, then the system-level blocktime ends here. + */ + if (dc->smp_cpus_down == smp_cpus && iter.affected_cpus) { + dc->total_blocktime += iter.current - dc->last_begin; } - trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime, - affected_cpu); + dc->smp_cpus_down -= iter.affected_cpus; + + trace_postcopy_blocktime_end(addr, iter.current, iter.affected_cpus, + iter.affected_non_cpus); } static void postcopy_pause_fault_thread(MigrationIncomingState *mis) @@ -964,7 +1280,7 @@ static void *postcopy_ram_fault_thread(void *opaque) trace_postcopy_ram_fault_thread_entry(); rcu_register_thread(); mis->last_rb = NULL; /* last RAMBlock we sent part of */ - qemu_sem_post(&mis->thread_sync_sem); + qemu_event_set(&mis->thread_sync_event); struct pollfd *pfd; size_t pfd_len = 2 + mis->postcopy_remote_fds->len; @@ -1068,17 +1384,14 @@ static void *postcopy_ram_fault_thread(void *opaque) qemu_ram_get_idstr(rb), rb_offset, msg.arg.pagefault.feat.ptid); - mark_postcopy_blocktime_begin( - (uintptr_t)(msg.arg.pagefault.address), - msg.arg.pagefault.feat.ptid, rb); - retry: /* * Send the request to the source - we want to request one * of our host page sizes (which is >= TPS) */ ret = postcopy_request_page(mis, rb, rb_offset, - msg.arg.pagefault.address); + msg.arg.pagefault.address, + msg.arg.pagefault.feat.ptid); if (ret) { /* May be network failure, try to wait for recovery */ postcopy_pause_fault_thread(mis); @@ -1221,6 +1534,11 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis) return -1; } + if (migrate_postcopy_blocktime()) { + assert(mis->blocktime_ctx == NULL); + mis->blocktime_ctx = blocktime_context_new(); + } + /* Now an eventfd we use to tell the fault-thread to quit */ mis->userfault_event_fd = eventfd(0, EFD_CLOEXEC); if (mis->userfault_event_fd == -1) { @@ -1299,8 +1617,8 @@ static int qemu_ufd_copy_ioctl(MigrationIncomingState *mis, void *host_addr, qemu_cond_signal(&mis->page_request_cond); } } - qemu_mutex_unlock(&mis->page_request_mutex); mark_postcopy_blocktime_end((uintptr_t)host_addr); + qemu_mutex_unlock(&mis->page_request_mutex); } return ret; } @@ -1430,6 +1748,11 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, { g_assert_not_reached(); } + +void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid, + RAMBlock *rb) +{ +} #endif /* ------------------------------------------------------------------------- */ @@ -1716,7 +2039,7 @@ void *postcopy_preempt_thread(void *opaque) rcu_register_thread(); - qemu_sem_post(&mis->thread_sync_sem); + qemu_event_set(&mis->thread_sync_event); /* * The preempt channel is established in asynchronous way. Wait |