diff options
Diffstat (limited to 'migration/postcopy-ram.c')
| -rw-r--r-- | migration/postcopy-ram.c | 143 |
1 files changed, 142 insertions, 1 deletions
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 88f3de44ad..ca8c3bce8e 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -553,6 +553,142 @@ static int ram_block_enable_notify(const char *block_name, void *host_addr, return 0; } +static int get_mem_fault_cpu_index(uint32_t pid) +{ + CPUState *cpu_iter; + + 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; + } + } + trace_get_mem_fault_cpu_index(-1, pid); + return -1; +} + +/* + * This function is being called when pagefault occurs. It + * tracks down vCPU blocking time. + * + * @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) +{ + int cpu, already_received; + MigrationIncomingState *mis = migration_incoming_get_current(); + PostcopyBlocktimeContext *dc = mis->blocktime_ctx; + int64_t now_ms; + + if (!dc || ptid == 0) { + return; + } + cpu = get_mem_fault_cpu_index(ptid); + if (cpu < 0) { + return; + } + + now_ms = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); + if (dc->vcpu_addr[cpu] == 0) { + atomic_inc(&dc->smp_cpus_down); + } + + atomic_xchg__nocheck(&dc->last_begin, now_ms); + atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], now_ms); + atomic_xchg__nocheck(&dc->vcpu_addr[cpu], addr); + + /* check it here, not at the begining of the function, + * due to, check could accur early than bitmap_set in + * qemu_ufd_copy_ioctl */ + already_received = ramblock_recv_bitmap_test(rb, (void *)addr); + if (already_received) { + atomic_xchg__nocheck(&dc->vcpu_addr[cpu], 0); + atomic_xchg__nocheck(&dc->page_fault_vcpu_time[cpu], 0); + atomic_dec(&dc->smp_cpus_down); + } + 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. + * + * + * Assume we have 3 CPU + * + * S1 E1 S1 E1 + * -----***********------------xxx***************------------------------> CPU1 + * + * S2 E2 + * ------------****************xxx---------------------------------------> CPU2 + * + * S3 E3 + * ------------------------****xxx********-------------------------------> CPU3 + * + * We have sequence S1,S2,E1,S3,S1,E2,E3,E1 + * S2,E1 - doesn't match condition due to sequence S1,S2,E1 doesn't include CPU3 + * S3,S1,E2 - sequence includes all CPUs, in this case overlap will be S1,E2 - + * it's a part of total blocktime. + * S1 - here is last_begin + * Legend of the picture is following: + * * - means blocktime per vCPU + * x - means overlapped blocktime (total blocktime) + * + * @addr: host virtual address + */ +static void mark_postcopy_blocktime_end(uintptr_t addr) +{ + MigrationIncomingState *mis = migration_incoming_get_current(); + PostcopyBlocktimeContext *dc = mis->blocktime_ctx; + int i, affected_cpu = 0; + int64_t now_ms; + bool vcpu_total_blocktime = false; + int64_t read_vcpu_time; + + if (!dc) { + return; + } + + now_ms = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); + + /* lookup cpu, to clear it, + * that algorithm looks straighforward, 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++) { + uint64_t vcpu_blocktime = 0; + + read_vcpu_time = atomic_fetch_add(&dc->page_fault_vcpu_time[i], 0); + if (atomic_fetch_add(&dc->vcpu_addr[i], 0) != addr || + read_vcpu_time == 0) { + continue; + } + atomic_xchg__nocheck(&dc->vcpu_addr[i], 0); + vcpu_blocktime = now_ms - 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 && + atomic_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; + } + + atomic_sub(&dc->smp_cpus_down, affected_cpu); + if (vcpu_total_blocktime) { + dc->total_blocktime += now_ms - atomic_fetch_add(&dc->last_begin, 0); + } + trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime, + affected_cpu); +} + /* * Handle faults detected by the USERFAULT markings */ @@ -630,8 +766,11 @@ static void *postcopy_ram_fault_thread(void *opaque) rb_offset &= ~(qemu_ram_pagesize(rb) - 1); trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address, qemu_ram_get_idstr(rb), - rb_offset); + rb_offset, + msg.arg.pagefault.feat.ptid); + mark_postcopy_blocktime_begin((uintptr_t)(msg.arg.pagefault.address), + msg.arg.pagefault.feat.ptid, rb); /* * Send the request to the source - we want to request one * of our host page sizes (which is >= TPS) @@ -721,6 +860,8 @@ static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr, if (!ret) { ramblock_recv_bitmap_set_range(rb, host_addr, pagesize / qemu_target_page_size()); + mark_postcopy_blocktime_end((uintptr_t)host_addr); + } return ret; } |