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mckernel/NEWS.md
Masamichi Takagi 0aeab6b840 NEWS.md: Add 1.7.0rc4 updates 
Change-Id: I66ccbe5e8454482155243b89d9b0398994186010
2020-04-17 02:43:56 +00:00

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============================================= What's new in version 1.7.0rc4 (Apr 15, 2020)

McKernel major updates

  1. arm64: Contiguous PTE support
  2. arm64: Scalable Vector Extension (SVE) support
  3. arm64: PMU overflow interrupt support
  4. xpmem: Support large page attachment
  5. arm64 port: Direct access to Mckernel memory from Linux
  6. arm64 port: utility thread offloading, which spawns thread onto Linux CPU
  7. eclair: support for live debug
  8. Crash utility extension
  9. Replace mcoverlayfs with a soft userspace overlay
  10. Build system is switched to cmake
  11. Core dump includes thread information

McKernel major bug fixes

  1. shmobj: Fix rusage counting for large page
  2. mcctrl control: task start_time changed to u64 nsec
  3. mcctrl: add handling for one more level of page tables
  4. Add kernel argument to turn on/off time sharing
  5. flatten_string/process env: realign env and clear trailing bits
  6. madvise: Add MADV_HUGEPAGE support
  7. mcctrl: remove in-kernel calls to syscalls
  8. arch_cpu_read_write_register: error return fix.
  9. set_cputime(): interrupt enable/disable fix.
  10. set_mempolicy(): Add mode check.
  11. mbind(): Fix memory_range_lock deadlock.
  12. ihk_ikc_recv: Record channel to packet for release
  13. Add set_cputime() kernel to kernel case and mode enum.
  14. execve: Call preempt_enable() before error-exit
  15. memory/x86_64: fix linux safe_kernel_map
  16. do_kill(): fix pids table when nr of threads is larger than num_processors
  17. shmget: Use transparent huge pages when page size isn't specified
  18. prctl: Add support for PR_SET_THP_DISABLE and PR_GET_THP_DISABLE
  19. monitor_init: fix undetected hang on highest numbered core
  20. init_process_stack: change premapped stack size based on arch
  21. x86 syscalls: add a bunch of XXat() delegated syscalls
  22. do_pageout: fix direct kernel-user access
  23. stack: add hwcap auxval
  24. perf counters: add arch-specific perf counters
  25. Added check of nohost to terminate_host().
  26. kmalloc: Fix address order in free list
  27. sysfs: use nr_cpu_ids for cpumasks (fixes libnuma parsing error on ARM)
  28. monitor_init: Use ihk_mc_cpu_info()
  29. Fix ThunderX2 write-combined PTE flag insanity
  30. ARM: eliminate zero page mapping (i.e, init_low_area())
  31. eliminate futex_cmpxchg_enabled check (not used and dereffed a NULL pointer)
  32. page_table: Fix return value of lookup_pte when ptl4 is blank
  33. sysfs: add missing symlinks for cpu/node
  34. Make Linux handler run when mmap to procfs.
  35. Separate mmap area from program loading (relocation) area
  36. move rusage into kernel ELF image (avoid dynamic alloc before NUMA init)
  37. arm: turn off cpu on panic
  38. page fault handler: protect thread accesses
  39. Register PPD and release_handler at the same time.
  40. fix to missing exclusive processing between terminate() and finalize_process().
  41. perfctr_stop: add flags to no 'disable_intens'
  42. fileobj, shmobj: free pages in object destructor (as opposed to page_unmap())
  43. clear_range_l1, clear_range_middle: Fix handling contiguous PTE
  44. do_mmap: don't pre-populate the whole file when asked for smaller segment
  45. invalidate_one_page: Support shmobj and contiguous PTE
  46. ubsan: fix undefined shifts
  47. x86: disable zero mapping and add a boot pt for ap trampoline
  48. rusage: Don't count PF_PATCH change
  49. Fixed time processing.
  50. copy_user_pte: vmap area not owned by McKernel
  51. gencore: Zero-clear ELF header and memory range table
  52. rpm: ignore CMakeCache.txt in dist and relax BuildRequires on cross build
  53. gencore: Allocate ELF header to heap instead of stack
  54. nanosleep: add cpu_pause() in spinwait loop
  55. init_process: add missing initializations to proc struct
  56. rus_vm_fault: always use a packet on the stack
  57. process stack: use PAGE_SIZE in aux vector
  58. copy_user_pte: base memobj copy on range & VR_PRIVATE
  59. arm64: ptrace: Fix overwriting 1st argument with return value
  60. page fault: use cow for private device mappings
  61. reproductible builds: remove most install paths in c code
  62. page fault: clear writable bit for non-dirtying access to shared ranges
  63. mcreboot/mcstop+release: support for regular user execution
  64. irqbalance_mck: replace extra service with service drop-in
  65. do_mmap: give addr argument a chance even if not MAP_FIXED
  66. x86: fix xchg() and cmpxchg() macros
  67. IHK: support for using Linux work IRQ as IKC interrupt (optional)
  68. MCS: fix ARM64 issue by using smp_XXX() functions (i.e., barrier()s)
  69. procfs: add number of threads to stat and status
  70. memory_range_lock: Fix deadlock in procfs/sysfs handler
  71. flush instruction cache at context switch time if necessary
  72. arm64: Fix PMU related functions
  73. page_fault_process_memory_range: Disable COW for VM region with zeroobj
  74. extend_process_region: Fall back to demand paging when not contiguous
  75. munmap: fix deadlock with remote pagefault on vm range lock
  76. procfs: if memory_range_lock fails, process later
  77. migrate-cpu: Prevent migration target from calling schedule() twice
  78. sched_request_migrate(): fix race condition between migration req and IRQs
  79. get_one_cpu_topology: Renumber core_id (physical core id)
  80. bb7e140 procfs cpuinfo: use sequence number as processor
  81. set_host_vma(): do NOT read protect Linux VMA

=========================================== What's new in V1.6.0 (Nov 11, 2018)

McKernel new features, improvements and changes

  1. McKernel and Linux share one unified kernel virtual address space. That is, McKernel sections resides in Linux sections spared for modules. In this way, Linux can access the McKernel kernel memory area.
  2. hugetlbfs support
  3. IHK is now included as a git submodule
  4. Debug messages are turned on/off in per souce file basis at run-time.
  5. It's prohibited for McKernel to access physical memory ranges which Linux didn't give to McKernel.
  6. UTI (capability to spawn a thread on Linux CPU) improvement:
    • System calls issued from the thread are hooked by modifying binary in memory.

McKernel bug fixes (digest)

# below corresponds to the redmine issue number (https://postpeta.pccluster.org/redmine/).

  1. #926: shmget: Hide object with IPC_RMID from shmget
  2. #1028: init_process: Inherit parent cpu_set
  3. #995: Fix shebang recorded in argv[0]
  4. #1024: Fix VMAP virtual address leak
  5. #1109: init_process_stack: Support "ulimit -s unlimited"
  6. x86 mem init: do not map identity mapping
  7. mcexec_wait_syscall: requeue potential request on interrupted wait
  8. mcctrl_ikc_send_wait: fix interrupt with do_frees == NULL
  9. pager_req_read: handle short read
  10. kprintf: only call eventfd() if it is safe to interrupt
  11. process_procfs_request: Add Pid to /proc//status
  12. terminate: fix oversubscribe hang when waiting for other threads on same CPU to die
  13. mcexec: Do not close fd returned to mckernel side
  14. #976: execve: Clear sigaltstack and fp_regs
  15. #1002: perf_event: Specify counter by bit_mask on start/stop
  16. #1027: schedule: Don't reschedule immediately when wake up on migrate
  17. #mcctrl: lookup unexported symbols at runtime
  18. __sched_wakeup_thread: Notify interrupt_exit() of re-schedule
  19. futex_wait_queue_me: Spin-sleep when timeout and idle_halt is specified
  20. #1167: ihk_os_getperfevent,setperfevent: Timeout IKC sent by mcctrl
  21. devobj: fix object size (POSTK_DEBUG_TEMP_FIX_36)
  22. mcctrl: remove rus page cache
  23. #1021: procfs: Support multiple reads of e.g. /proc/*/maps
  24. #1006: wait: Delay wake-up parent within switch context
  25. #1164: mem: Check if phys-mem is within the range of McKernel memory
  26. #1039: page_fault_process_memory_range: Remove ihk_mc_map_virtual for CoW of device map
  27. partitioned execution: pass process rank to LWK
  28. process/vm: implement access_ok()
  29. spinlock: rewrite spinlock to use Linux ticket head/tail format
  30. #986: Fix deadlock involving mmap_sem and memory_range_lock
  31. Prevent one CPU from getting chosen by concurrent forks
  32. #1009: check_signal: system call restart is done only once
  33. #1176: syscall: the signal received during system call processing is not processed.
  34. #1036 syscall_time: Handle by McKernel
  35. #1165 do_syscall: Delegate system calls to the mcexec with the same pid
  36. #1194 execve: Fix calling ptrace_report_signal after preemption is disabled
  37. #1005 coredump: Exclude special areas
  38. #1018 procfs: Fix pread/pwrite to procfs fail when specified size is bigger than 4MB
  39. #1180 sched_setaffinity: Check migration after decrementing in_interrupt
  40. #771, #1179, #1143 ptrace supports threads
  41. #1189 procfs/do_fork: wait until procfs entries are registered
  42. #1114 procfs: add '/proc/pid/stat' to mckernel side and fix its comm
  43. #1116 mcctrl procfs: check entry was returned before using it
  44. #1167 ihk_os_getperfevent,setperfevent: Return -ETIME when IKC timeouts
  45. mcexec/execve: fix shebangs handling
  46. procfs: handle 'comm' on mckernel side
  47. ihk_os_setperfevent: Return number of registered events
  48. mcexec: fix terminating zero after readlink()

=========================================== What's new in V1.5.1 (July 9, 2018)

McKernel new features, improvements and changes

  1. Watchdog timer to detect hang of McKernel mcexec prints out the following line to its stderr when a hang of McKernel is detected.

    mcexec detected hang of McKernel

    The watchdog timer is enabled by passing -i <timeout_in_sec> option to mcreboot.sh. <timeout_in_sec> specifies the interval of checking if McKernel is alive. Example: mcreboot.sh -i 600: Detect the hang with 10 minutes interval

    The detailed step of the hang detection is as follows. (1) mcexec acquires eventfd for notification from IHK and perform epoll() on it. (2) A daemon called ihkmond monitors the state of McKernel periodically with the interval specified by the -i option. It judges that McKernel is hanging and notifies mcexec by the eventfd if its state hasn't changed since the last check.

  2. Documentation man page: Installed directory is changed to <install_dir>/share/man

McKernel bug fixes (digest)

  1. #1146: pager_req_map(): do not take mmap_sem if not needed
  2. #1135: prepare_process_ranges_args_envs(): fix saving cmdline
  3. #1144: fileobj/devobj: record path name
  4. #1145: fileobj: use MCS locks for per-file page hash
  5. #1076: mcctrl: refactor prepare_image into new generic ikc send&wait
  6. #1072: execve: fix execve with oversubscribing
  7. #1132: execve: use thread variable instead of cpu_local_var(current)
  8. #1117: mprotect: do not set page table writable for cow pages
  9. #1143: syscall wait4: add _WALL (POSTK_DEBUG_ARCH_DEP_44)
  10. #1064: rusage: Fix initialization of rusage->num_processors
  11. #1133: pager_req_unmap: Put per-process data at exit
  12. #731: do_fork: Propagate error code returned by mcexec
  13. #1149: execve: Reinitialize vm_regions's map area on execve
  14. #1065: procfs: Show file names in /proc//maps
  15. #1112: mremap: Fix type of size arguments (from ssize_t to size_t)
  16. #1121: sched_getaffinity: Check arguments in the same order as in Linux
  17. #1137: mmap, mremap: Check arguments in the same order as in Linux
  18. #1122: fix return value of sched_getaffinity
  19. #732: fix: /proc//maps outputs a unnecessary NULL character

=================================== What's new in V1.5.0 (Apr 5, 2018)

McKernel new features and improvements

  1. Aid for Linux version migration: Detect /proc, /sys format change between two kernel verions
  2. Swap out
    • Only swap-out anonymous pages for now
  3. Improve support of /proc/maps
  4. mcstat: Linux tool to show resource usage

McKernel bug fixes (digest)

  1. #727: execve: Fix memory leak when receiving SIGKILL
  2. #829: perf_event_open: Support PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
  3. #906: mcexec: Check return code of fork()
  4. #1038: mcexec: Timeout when incorrect value is given to -n option
  5. #943 #945 #946 #960 $961: mcexec: Support strace
  6. #1029: struct thread is not released with stress-test involving signal and futex
  7. #863 #870: Respond immediately to terminating signal when offloading system call
  8. #1119: translate_rva_to_rpa(): use 2MB blocks in 1GB pages on x86
  9. #898: Shutdown OS only after no in-flight IKC exist
  10. #882: release_handler: Destroy objects as the process which opened it
  11. #882: mcexec: Make child process exit if the parent is killed during fork()
  12. #925: XPMEM: Don't destroy per-process object of the parent
  13. #885: ptrace: Support the case where a process attaches its child
  14. #1031: sigaction: Support SA_RESETHAND
  15. #923: rus_vm_fault: Return error when a thread not performing system call offloading causes remote page fault
  16. #1032 #1033 #1034: getrusage: Fix ru_maxrss, RUSAGE_CHILDREN, ru_stime related bugs
  17. #1120: getrusage: Fix deadlock on thread->times_update
  18. #1123: Fix deadlock related to wait_queue_head_list_node
  19. #1124: Fix deadlock of calling terminate() from terminate()
  20. #1125: Fix deadlock related to thread status
    • Related functions are: hold_thread(), do_kill() and terminate()
  21. #1126: uti: Fix uti thread on the McKernel side blocks others in do_syscall()
  22. #1066: procfs: Show Linux /proc/self/cgroup
  23. #1127: prepare_process_ranges_args_envs(): fix generating saved_cmdline to avoid PF in strlen()
  24. #1128: ihk_mc_map/unmap_virtual(): do proper TLB invalidation
  25. #1043: terminate(): fix update_lock and threads_lock order to avoid deadlock
  26. #1129: mcreboot.sh: Save /proc/irq/*/smp_affinity to /tmp/mcreboot
  27. #1130: mcexec: drop READ_IMPLIES_EXEC from personality

McKernel workarounds

  1. Forbid CPU oversubscription
    • It can be turned on by mcreboot.sh -O option

=================================== What's new in V1.4.0 (Oct 30, 2017)

Feature: Abstracted event type support in perf_event_open()

PERF_TYPE_HARDWARE and PERF_TYPE_CACHE types are supported.

Clean-up: Direct user-space access

Code lines using direct user-space access (e.g. passing user-space pointer to memcpy()) becomes more portable across processor architectures. The modification follows the following rules.

  1. Move the code section as it is to the architecture dependent directory if it is a part of the critical-path.
  2. Otherwise, rewrite the code section by using the portable methods. The methods include copy_from_user(), copy_to_user(), pte_get_phys() and phys_to_virt().

Test: MPI and OpenMP micro-bench

The performance figures of MPI and OpenMP primitives are compared with those of Linux by using Intel MPI Benchmarks and EPCC OpenMP Micro Benchmark.

=================================== What's new in V1.3.0 (Sep 30, 2017)

Feature: Kernel dump

  1. A dump level of "only kernel memory" is added.

The following two levels are available now: 0: Dump all 24: Dump only kernel memory

The dump level can be set by -d option in ihkosctl or the argument for ihk_os_makedumpfile(), as shown in the following examples:

Command: ihkosctl 0 dump -d 24 Function call: ihk_os_makedumpfile(0, NULL, 24, 0);

  1. Dump file is created when Linux panics.

The dump level can be set by dump_level kernel argument, as shown in the following example:

ihkosctl 0 kargs "hidos dump_level=24"

The IHK dump function is registered to panic_notifier_list when creating /dev/mcdX and called when Linux panics.

Feature: Quick Process Launch

MPI process launch time and some of the initialization time can be reduced in application consisting of multiple MPI programs which are launched in turn in the job script.

The following two steps should be performed to use this feature:

  1. Replace mpiexec with ql_mpiexec_start and add some lines for ql_mpiexec_finalize in the job script
  2. Modify the app so that it can repeat calculations and wait for the instructions from ql_mpiexec_{start,finalize} at the end of the loop

The first step is explained using an example. Assume the original job script looks like this:

/* Execute ensamble simulation and then data assimilation, and repeat this ten times */ for i in {1..10}; do

 /* Each ensamble simulation execution uses 100 nodes, launch ten of them
    in parallel */
for j in {1..10}; do
     mpiexec -n 100 -machinefile ./list1_$j p1.out a1 & pids[$i]=$!;
done

/* Wait until the ten ensamble simulation programs finish */
for j in {1..10}; do wait ${pids[$j]}; done

/* Launch one data assimilation program using 1000 nodes */
mpiexec -n 1000 -machinefile ./list2 p2.out a2

done

The job script should be modified like this:

for i in {1..10}; do for j in {1..10}; do /* Replace mpiexec with ql_mpiexec_start */ ql_mpiexec_start -n 100 -machinefile ./list1_$j p1.out a1 & pids[j]=!; done

for j in {1..10}; do wait ${pids[$j]}; done

ql_mpiexec_start -n 1000 -machinefile ./list2 p2.out a2

done

/* p1.out and p2.out don't exit but are waiting for the next calculation. So tell them to exit */ for j in {1..10}; do ql_mpiexec_finalize -machinefile ./list1_$i p1.out a1; done ql_mpiexec_finalize -machinefile ./list2 p2.out a2;

The second step is explained using a pseudo-code.

MPI_Init();
Prepare data exchange with preceding / following MPI programs

loop: foreach Fortran module Initialize data using command-line argments, parameter files, environment variables Input data from preceding MPI programs / Read snap-shot Perform main calculation Output data to following MPI programs / Write snap-shot /* ql_client() waits for command of ql_mpiexec_{start,finish} */ if (ql_client() == QL_CONTINUE) { goto loop; } MPI_Finalize();

qlmpilib.h should be included in the code and libql{mpi,fort}.so should be linked to the executable file.

======================== Restrictions on McKernel

  1. Pseudo devices such as /dev/mem and /dev/zero are not mmap()ed correctly even if the mmap() returns a success. An access of their mapping receives the SIGSEGV signal.

  2. clone() supports only the following flags. All the other flags cause clone() to return error or are simply ignored.

    • CLONE_CHILD_CLEARTID
    • CLONE_CHILD_SETTID
    • CLONE_PARENT_SETTID
    • CLONE_SETTLS
    • CLONE_SIGHAND
    • CLONE_VM

  3. PAPI has the following restriction.

    • Number of counters a user can use at the same time is up to the number of the physical counters in the processor.

  4. msync writes back only the modified pages mapped by the calling process.

  5. The following syscalls always return the ENOSYS error.

    • migrate_pages()
    • move_pages()
    • set_robust_list()

  6. The following syscalls always return the EOPNOTSUPP error.

    • arch_prctl(ARCH_SET_GS)
    • signalfd()

  7. signalfd4() returns a fd, but signal is not notified through the fd.

  8. set_rlimit sets the limit values but they are not enforced.

  9. Address randomization is not supported.

  10. brk() extends the heap more than requestd when -h (--extend-heap-by=) option of mcexec is used with the value larger than 4 KiB. syscall_pwrite02 of LTP would fail for this reason. This is because the test expects that the end of the heap is set to the same address as the argument of sbrk() and expects a segmentation violation occurs when it tries to access the memory area right next to the boundary. However, the optimization sets the end to a value larger than the requested. Therefore, the expected segmentation violation doesn't occur.

  11. setpriority()/getpriority() won't work. They might set/get the priority of a random mcexec thread. This is because there's no fixed correspondence between a McKernel thread which issues the system call and a mcexec thread which handles the offload request.

  12. mbind() can set the policy but it is not used when allocating physical pages.

  13. MPOL_F_RELATIVE_NODES and MPOL_INTERLEAVE flags for set_mempolicy()/mbind() are not supported.

  14. The MPOL_BIND policy for set_mempolicy()/mbind() works as the same as the MPOL_PREFERRED policy. That is, the physical page allocator doesn't give up the allocation when the specified nodes are running out of pages but continues to search pages in the other nodes.

  15. Kernel dump on Linux panic requires Linux kernel CentOS-7.4 and later. In addition, crash_kexec_post_notifiers kernel argument must be given to Linux kernel.

  16. setfsuid()/setfsgid() cannot change the id of the calling thread. Instead, it changes that of the mcexec worker thread which takes the system-call offload request.

  17. mmap (hugeTLBfs): The physical pages corresponding to a map are released when no McKernel process exist. The next map gets fresh physical pages.

  18. Sticky bit on executable file has no effect.

  19. Linux (RHEL-7 for x86_64) could hang when offlining CPUs in the process of booting McKernel due to the Linux bug, found in Linux-3.10 and fixed in the later version. One way to circumvent this is to always assign the same CPU set to McKernel.

  20. madvise:

    • MADV_HWPOISON and MADV_SOFT_OFFLINE always returns -EPERM.
    • MADV_MERGEABLE and MADV_UNMERGEABLE always returns -EINVAL.
    • MADV_HUGEPAGE and MADV_NOHUGEPAGE on file map returns -EINVAL (It succeeds on RHEL-8 for aarch64).

  21. brk() and mmap() doesn't report out-of-memory through its return value. Instead, page-fault reports the error.

  22. Anonymous mmap pre-maps requested number of pages when contiguous pages are available. Demand paging is used when not available.

  23. Mixing page sizes in anonymous shared mapping is not allowed. mmap creates vm_range with one page size. And munmap or mremap that needs the reduced page size changes the sizes of all the pages of the vm_range.

  24. ihk_os_getperfevent() could time-out when invoked from Fujitsu TCS (job-scheduler).