[user@machine ~]$ ulimit -a real-time non-blocking time (microseconds, -R) unlimited core file size (blocks, -c) unlimited data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 127205 max locked memory (kbytes, -l) 8192 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) unlimited virtual memory (kbytes, -v) unlimited file locks (-x) unlimited # ulimit default nofile(-n) user soft nofile 262143 user hard nofile 262143
# nporc. # change ulimit -u to unlimited or increase it. -bash: fork: retry: Resource temporarily unavailable -bash: fork: retry: No child processes -bash: fork: retry: No child processes -bash: fork: retry: No child processes [user@machine ~]$ ulimit -u unlimited [user@machine limits.d]$ cat /etc/security/limits.d/user1.conf # Default limit for number of user's processes to prevent # accidental fork bombs. # See rhbz #432903 for reasoning. user1 soft nproc unlimited user1 hard nproc unlimited
# tcp buffer [user@machine ~]$ vim /etc/sysctl.d/100-custom.conf net.core.wmem_max = 67108864 net.ipv4.tcp_wmem = 4096 2097152 67108864 [user@machine ~]$ sysctl -p /etc/sysctl.d/100-custom.conf # allow TCP with buffers up to 64MB (64*1024*1024=67108864) net.core.rmem_max = 67108864 net.core.wmem_max = 67108864 # increase Linux autotuning TCP buffer limit to 32MB net.ipv4.tcp_rmem = 4096 87380 33554432 net.ipv4.tcp_wmem = 4096 65536 33554432 # recommended for hosts with jumbo frames enabled net.ipv4.tcp_mtu_probing=1 # recommended to use a 'fair queueing' qdisc (either fq or fq_codel) net.core.default_qdisc = fq For a host with a 10G NIC optimized for network paths up to 200ms RTT, and for friendliness to single and parallel stream tools, or a 40G NIC up on paths up to 50ms RTT: # allow TCP with buffers up to 128MB net.core.rmem_max = 134217728 net.core.wmem_max = 134217728 For a host with a 100G NIC optimized for network paths up to 200ms RTT, use this config: # allow TCP with buffers up to 2GB (Max allowed in Linux is 2GB-1) net.core.rmem_max=2147483647 net.core.wmem_max=2147483647 # https://fasterdata.es.net/host-tuning/linux/ # https://fasterdata.es.net/host-tuning/linux/test-measurement-host-tuning/ # max size vm.nr_hugepages = 16384 # hugepages on /etc/sysctl.d/
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