1 # change the minimum size of the hugepage pool.
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4 # this file contains the maximum number of memory map areas a process
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5 # may have. memory map areas are used as a side-effect of calling
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6 # malloc, directly by mmap and mprotect, and also when loading shared
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9 # while most applications need less than a thousand maps, certain
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10 # programs, particularly malloc debuggers, may consume lots of them,
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11 # e.g., up to one or two maps per allocation.
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12 # must be greater than or equal to (2 * vm.nr_hugepages).
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13 vm.max_map_count=200000
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15 # hugetlb_shm_group contains group id that is allowed to create sysv
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16 # shared memory segment using hugetlb page.
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17 vm.hugetlb_shm_group=0
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19 # this control is used to define how aggressive the kernel will swap
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20 # memory pages. higher values will increase agressiveness, lower values
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21 # decrease the amount of swap. a value of 0 instructs the kernel not to
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22 # initiate swap until the amount of free and file-backed pages is less
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23 # than the high water mark in a zone.
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26 # this parameter can be used to control the nmi watchdog
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27 # (i.e. the hard lockup detector) on x86 systems.
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29 # 0 - disable the hard lockup detector
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30 # 1 - enable the hard lockup detector
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32 # the hard lockup detector monitors each cpu for its ability to respond to
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33 # timer interrupts. the mechanism utilizes cpu performance counter registers
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34 # that are programmed to generate non-maskable interrupts (nmis) periodically
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35 # while a cpu is busy. hence, the alternative name 'nmi watchdog'.
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37 # the nmi watchdog is disabled by default if the kernel is running as a guest
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38 # in a kvm virtual machine. this default can be overridden by adding
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39 #kernel. nmi_watchdog=1
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41 # shared memory max must be greator or equal to the total size of hugepages.
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42 # for 2mb pages, totalhugepagesize = vm.nr_hugepages * 2 * 1024 * 1024
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43 # if the existing kernel.shmmax setting (cat /sys/proc/kernel/shmmax)
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44 # is greater than the calculated totalhugepagesize then set this parameter
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45 # to current shmmax value.
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46 kernel.shmmax=8589934592
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48 # this option can be used to select the type of process address
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49 # space randomization that is used in the system, for architectures
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50 # that support this feature.
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51 # 0 - turn the process address space randomization off. this is the
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52 # default for architectures that do not support this feature anyways,
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53 # and kernels that are booted with the "norandmaps" parameter.
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54 kernel.randomize_va_space=0
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56 # this parameter can be used to control the soft lockup detector.
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58 # 0 - disable the soft lockup detector
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59 # 1 - enable the soft lockup detector
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61 # the soft lockup detector monitors cpus for threads that are hogging the cpus
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62 # without rescheduling voluntarily, and thus prevent the 'watchdog/n' threads
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63 # from running. the mechanism depends on the cpus ability to respond to timer
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64 # interrupts which are needed for the 'watchdog/n' threads to be woken up by
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65 # the watchdog timer function, otherwise the nmi watchdog - if enabled - can
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66 # detect a hard lockup condition.
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67 #kernel.soft_watchdog=0
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69 # this value can be used to control on which cpus the watchdog may run.
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70 # the default cpumask is all possible cores, but if no_hz_full is
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71 # enabled in the kernel config, and cores are specified with the
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72 # nohz_full= boot argument, those cores are excluded by default.
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73 # offline cores can be included in this mask, and if the core is later
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74 # brought online, the watchdog will be started based on the mask value.
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76 # typically this value would only be touched in the nohz_full case
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77 # to re-enable cores that by default were not running the watchdog,
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78 # if a kernel lockup was suspected on those cores.
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79 kernel.watchdog_cpumask=0,18
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