On 14/01/2015 11:20, Kevin Wolf wrote: >> > The same problem applies to coroutine stacks, and those cannot be >> > throttled down as easily. But I guess if you limit the number of >> > threads, the guest gets slowed down and doesn't create as many coroutines. > Shouldn't we rather try and decrease the stack sizes a bit? 1 MB per > coroutine is really a lot, and as I understand it, threads take even > more by default.
Yup, 2 MB. Last time I proposed this, I think Markus was strongly in the "better safe than sorry" camp. :) But thread pool workers definitely don't need a big stack. >> > It would be nice to have a way to measure coroutine stack usage, similar >> > to what the kernel does. > The information which pages are mapped should be there somewhere... Yes, there is mincore(2). The complicated part is doing it fast, but perhaps it doesn't need to be fast. I tried gathering warning from GCC's -Wstack-usage=1023 option and the block layer does not seem to have functions with huge stacks in the I/O path. So, assuming a maximum stack depth of 50 (already pretty generous since there shouldn't be any recursive calls) a 100K stack should be pretty much okay for coroutines and thread-pool threads. That said there are some offenders in the device models. Other QemuThreads, especially VCPU threads, had better stay with a big stack. Paolo 1024-2048: block/linux-aio.c ioq_submit stack usage is 1104 bytes block/mirror.c mirror_run stack usage is 1280 bytes block/qapi.c bdrv_query_image_info stack usage is 1152 bytes block/vmdk.c vmdk_open_vmdk4 stack usage is 1840 bytes block/vpc.c vpc_create stack usage is 1152 bytes cpus.c qmp_memsave stack usage is 1120 bytes cpus.c qmp_pmemsave stack usage is 1120 bytes disas/sparc.c build_hash_table stack usage is 1072 bytes fsdev/virtfs-proxy-helper.c main stack usage is 1264 bytes hw/arm/highbank.c calxeda_init stack usage is 1200 bytes hw/arm/stellaris.c stellaris_init stack usage is 1120 bytes hw/arm/virt.c machvirt_init stack usage is 1264 bytes hw/block/dataplane/virtio-blk.c handle_notify stack usage is 1632 bytes hw/block/virtio-blk.c virtio_blk_dma_restart_bh stack usage is 1600 bytes hw/block/virtio-blk.c virtio_blk_handle_output stack usage is 1584 bytes hw/core/qdev.c qdev_get_legacy_property stack usage is 1104 bytes hw/net/vmxnet_tx_pkt.c vmxnet_tx_pkt_do_sw_fragmentation stack usage is 1168 bytes hw/ppc/e500.c ppce500_load_device_tree stack usage is 1072 bytes hw/scsi/megasas.c megasas_dcmd_ld_get_list stack usage is 1152 bytes hw/tpm/tpm_passthrough.c tpm_passthrough_test_tpmdev stack usage is 1216 bytes linux-user/main.c main stack usage is 1664 bytes linux-user/main.c main stack usage is 1696 bytes linux-user/main.c main stack usage is 1728 bytes linux-user/main.c main stack usage is 1744 bytes linux-user/main.c main stack usage is 1760 bytes linux-user/main.c main stack usage is 1776 bytes linux-user/main.c main stack usage is 1856 bytes linux-user/main.c main stack usage is 1872 bytes linux-user/main.c main stack usage is 1888 bytes linux-user/main.c main stack usage is 1952 bytes linux-user/main.c main stack usage is 1984 bytes linux-user/main.c main stack usage is 2032 bytes migration/vmstate.c get_unused_buffer stack usage is 1088 bytes monitor.c monitor_parse_command stack usage is 1424 bytes monitor.c parse_cmdline stack usage is 1136 bytes qemu-img.c img_rebase stack usage is 1248 bytes qobject/json-parser.c parse_error stack usage is 1280 bytes qobject/qjson.c to_json stack usage is 1136 bytes qtest.c qtest_send stack usage is 1280 bytes savevm.c do_savevm stack usage is 1424 bytes slirp/slirp.c if_encap stack usage is 1680 bytes target-i386/kvm.c kvm_get_apic stack usage is 1072 bytes target-i386/kvm.c kvm_put_apic stack usage is 1072 bytes target-xtensa/xtensa-semi.c helper_simcall stack usage is 1296 bytes trace/control.c trace_init_events stack usage is 1152 bytes ui/keymaps.c parse_keyboard_layout stack usage is 1152 bytes ui/vnc.c addr_to_string stack usage is 1136 bytes ui/vnc.c protocol_client_init stack usage is 1072 bytes ui/vnc.c qmp_query_vnc stack usage is 1344 bytes ui/vnc.c vnc_basic_info_get stack usage is 1136 bytes ui/vnc-enc-tight.c tight_detect_smooth_image16 stack usage is 1184 bytes ui/vnc-enc-tight.c tight_detect_smooth_image24 stack usage is 1152 bytes ui/vnc-enc-tight.c tight_detect_smooth_image32 stack usage is 1184 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile15be stack usage is 1264 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile15le stack usage is 1264 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile16be stack usage is 1264 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile16le stack usage is 1264 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile24abe stack usage is 1200 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile24ale stack usage is 1200 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile24bbe stack usage is 1200 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile24ble stack usage is 1200 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile32be stack usage is 1184 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile32le stack usage is 1184 bytes ui/vnc-enc-zrle-template.c zrle_encode_tile8ne stack usage is 1184 bytes util/qemu-option.c opts_do_parse stack usage is 1280 bytes util/qemu-option.c opts_parse stack usage is 1104 bytes 2048-4096: block.c bdrv_swap stack usage is 3920 bytes coroutine-ucontext.c qemu_coroutine_new stack usage is 2192 bytes hw/arm/musicpal.c eth_send stack usage is 2160 bytes hw/dma/etraxfs_dma.c channel_out_run stack usage is 2160 bytes hw/net/cadence_gem.c gem_receive stack usage is 2192 bytes hw/net/cadence_gem.c gem_transmit stack usage is 2176 bytes hw/net/eepro100.c tx_command stack usage is 2736 bytes hw/net/mcf_fec.c mcf_fec_do_tx stack usage is 2144 bytes hw/ppc/spapr_pci.c spapr_populate_pci_dt stack usage is 4032 bytes hw/scsi/megasas.c megasas_ctrl_get_info stack usage is 2176 bytes libcacard/vcard_emul_nss.c vcard_emul_rsa_op stack usage is 2224 bytes monitor.c file_completion stack usage is 3328 bytes monitor.c host_net_remove_completion stack usage is 2176 bytes monitor.c netdev_del_completion stack usage is 2112 bytes monitor.c set_link_completion stack usage is 2112 bytes qemu-char.c tcp_chr_connect stack usage is 2608 bytes qemu-nbd.c main stack usage is 2336 bytes slirp/misc.c fork_exec stack usage is 2176 bytes slirp/socket.c sosendoob stack usage is 2144 bytes target-arm/helper.c register_cp_regs_for_features stack usage is 3232 bytes target-arm/helper.c register_cp_regs_for_features stack usage is 3360 bytes target-i386/kvm.c kvm_get_msrs stack usage is 2448 bytes target-i386/kvm.c kvm_put_msrs stack usage is 2448 bytes ui/sdl.c sdl_update_caption stack usage is 2112 bytes util/qemu-config.c qemu_config_parse stack usage is 2416 bytes 4096-8192: block.c bdrv_commit stack usage is 4208 bytes block/raw-posix.c hdev_open stack usage is 4320 bytes block/vmdk.c vmdk_parse_extents stack usage is 4848 bytes block/vvfat.c check_directory_consistency stack usage is 5152 bytes gdbstub.c gdb_monitor_output stack usage is 4144 bytes hw/arm/boot.c set_kernel_args stack usage is 4176 bytes hw/audio/ac97.c read_audio stack usage is 4208 bytes hw/audio/ac97.c write_audio stack usage is 4208 bytes hw/audio/es1370.c es1370_transfer_audio stack usage is 4240 bytes hw/audio/gus.c GUS_read_DMA stack usage is 4192 bytes hw/audio/marvell_88w8618.c mv88w8618_audio_callback stack usage is 4160 bytes hw/audio/milkymist-ac97.c ac97_in_cb stack usage is 4176 bytes hw/audio/milkymist-ac97.c ac97_out_cb stack usage is 4176 bytes hw/audio/sb16.c write_audio stack usage is 4192 bytes hw/char/sclpconsole-lm.c process_mdb stack usage is 4144 bytes hw/s390x/sclp.c sclp_service_call stack usage is 4336 bytes hw/scsi/lsi53c895a.c lsi_memcpy stack usage is 4192 bytes hw/scsi/megasas.c megasas_dcmd_cfg_read stack usage is 4224 bytes hw/scsi/megasas.c megasas_dcmd_pd_get_list stack usage is 5808 bytes hw/tpm/tpm_passthrough.c tpm_passthrough_open_sysfs_cancel stack usage is 4144 bytes linux-user/elfload.c vma_dump_size stack usage is 4128 bytes linux-user/syscall.c do_openat stack usage is 4176 bytes net/tap.c net_bridge_run_helper stack usage is 4720 bytes qemu-bridge-helper.c parse_acl_file stack usage is 4176 bytes qemu-char.c fd_chr_read stack usage is 4160 bytes qemu-char.c pty_chr_read stack usage is 4160 bytes qemu-char.c qemu_chr_fe_printf stack usage is 4352 bytes qemu-char.c qemu_chr_open_pty stack usage is 4176 bytes qemu-char.c tcp_chr_read stack usage is 4192 bytes qga/commands-posix.c get_pci_driver stack usage is 4144 bytes qga/main.c channel_event_cb stack usage is 4160 bytes target-i386/kvm.c kvm_arch_init_vcpu stack usage is 4144 bytes target-s390x/ioinst.c ioinst_handle_chsc_scsc stack usage is 4112 bytes target-s390x/misc_helper.c helper_stsi stack usage is 4128 bytes ui/vnc-auth-sasl.c vnc_client_read_sasl stack usage is 4160 bytes util/oslib-posix.c qemu_init_exec_dir stack usage is 4144 bytes util/path.c init_paths stack usage is 4144 bytes 8192-16384: block/vmdk.c vmdk_parent_open stack usage is 10288 bytes block/vmdk.c vmdk_read_cid stack usage is 10304 bytes gdbstub.c gdb_handle_packet stack usage is 8336 bytes hw/acpi/core.c acpi_table_add stack usage is 8336 bytes hw/audio/cs4231a.c cs_write_audio stack usage is 12384 bytes hw/core/qdev-properties-system.c set_netdev stack usage is 8288 bytes hw/i386/kvm/pci-assign.c assign_failed_examine stack usage is 12480 bytes hw/i386/pc.c load_linux stack usage is 8336 bytes hw/net/rtl8139.c rtl8139_transmit_one stack usage is 8256 bytes hw/net/xgmac.c xgmac_enet_send stack usage is 8288 bytes hw/s390x/s390-pci-inst.c clp_service_call stack usage is 8384 bytes hw/sparc64/sun4u.c sun4u_NVRAM_set_params stack usage is 8272 bytes hw/sparc/sun4m.c nvram_init stack usage is 8272 bytes hw/vfio/pci.c vfio_initfn stack usage is 8592 bytes linux-user/elfload.c elf_core_dump stack usage is 12640 bytes linux-user/elfload.c elf_core_dump stack usage is 8544 bytes linux-user/elfload.c vma_dump_size stack usage is 8224 bytes net/net.c qemu_del_net_client stack usage is 8256 bytes net/net.c qmp_set_link stack usage is 8256 bytes 16384+: block/vmdk.c vmdk_create stack usage is 29376 bytes block/vmdk.c vmdk_write_cid stack usage is 20544 bytes hw/arm/nseries.c n8x0_init stack usage is 65728 bytes hw/char/virtio-serial-bus.c control_out stack usage is 49312 bytes hw/char/virtio-serial-bus.c discard_vq_data stack usage is 49216 bytes hw/char/virtio-serial-bus.c send_control_msg stack usage is 49232 bytes hw/char/virtio-serial-bus.c write_to_port stack usage is 49264 bytes hw/display/vmware_vga.c vmsvga_fifo_run stack usage is 20688 bytes hw/dma/xilinx_axidma.c stream_process_mem2s stack usage is 16480 bytes hw/net/opencores_eth.c open_eth_start_xmit stack usage is 65600 bytes hw/net/virtio-net.c virtio_net_flush_tx stack usage is 65664 bytes hw/net/virtio-net.c virtio_net_handle_ctrl stack usage is 49424 bytes hw/net/virtio-net.c virtio_net_handle_ctrl stack usage is 49440 bytes hw/net/virtio-net.c virtio_net_receive stack usage is 65728 bytes hw/virtio/virtio-balloon.c virtio_balloon_handle_output stack usage is 49376 bytes hw/virtio/virtio-rng.c chr_read stack usage is 49264 bytes net/net.c nc_sendv_compat stack usage is 69680 bytes net/socket.c net_socket_send stack usage is 69712 bytes net/tap.c net_init_tap stack usage is 16704 bytes ui/vnc-jobs.c vnc_worker_thread_loop stack usage is 75632 bytes "might be unbounded": backends/baum.c baum_write_packet stack usage might be unbounded backends/baum.c baum_write stack usage might be unbounded backends/rng-random.c entropy_available stack usage might be unbounded block/qapi.c dump_qobject stack usage might be unbounded block/vpc.c vpc_co_write stack usage might be unbounded exec.c mem_commit stack usage might be unbounded hw/block/nvme.c nvme_map_prp stack usage might be unbounded hw/bt/l2cap.c l2cap_cframe_in stack usage might be unbounded hw/i386/multiboot.c load_multiboot stack usage might be unbounded hw/intc/xics.c ics_reset stack usage might be unbounded hw/net/fsl_etsec/rings.c etsec_walk_rx_ring stack usage might be unbounded hw/net/spapr_llan.c h_send_logical_lan stack usage might be unbounded hw/ppc/spapr.c spapr_fixup_cpu_dt stack usage might be unbounded hw/ppc/spapr_pci.c spapr_phb_realize stack usage might be unbounded hw/ssi/xilinx_spips.c xilinx_spips_flush_txfifo stack usage might be unbounded hw/usb/dev-hid.c usb_hid_handle_data stack usage might be unbounded hw/usb/dev-mtp.c usb_mtp_add_str stack usage might be unbounded hw/usb/dev-mtp.c usb_mtp_handle_data stack usage might be unbounded hw/usb/dev-wacom.c usb_wacom_handle_data stack usage might be unbounded hw/usb/hcd-xhci.c xhci_process_commands stack usage might be unbounded hw/usb/redirect.c usbredir_handle_data stack usage might be unbounded linux-user/elfload.c load_elf_image stack usage might be unbounded linux-user/elfload.c load_symbols stack usage might be unbounded linux-user/syscall.c do_accept4 stack usage might be unbounded linux-user/syscall.c do_bind stack usage might be unbounded linux-user/syscall.c do_connect stack usage might be unbounded linux-user/syscall.c do_getpeername stack usage might be unbounded linux-user/syscall.c do_getsockname stack usage might be unbounded linux-user/syscall.c do_recvfrom stack usage might be unbounded linux-user/syscall.c do_sendrecvmsg_locked stack usage might be unbounded linux-user/syscall.c do_sendto stack usage might be unbounded linux-user/syscall.c do_setsockopt stack usage might be unbounded linux-user/syscall.c do_syscall stack usage might be unbounded net/tap.c tap_receive_iov stack usage might be unbounded qemu-char.c tcp_chr_write stack usage might be unbounded target-arm/helper.c helper_dc_zva stack usage might be unbounded ui/vnc-enc-hextile-template.h send_hextile_tile_32 stack usage might be unbounded ui/vnc-enc-hextile-template.h send_hextile_tile_generic_32 stack usage might be unbounded ui/vnc-enc-tight.c send_palette_rect stack usage might be unbounded util/iov.c qemu_iovec_clone stack usage might be unbounded
