linux中HZ表示tick的频率，在param.h中定义

[root@vm100-1-3-5 ~]# find /usr -name param.h                
/usr/include/bits/param.h
/usr/include/sys/param.h
/usr/include/linux/param.h
/usr/include/asm-generic/param.h
/usr/include/asm/param.h
/usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/uapi/linux/param.h
/usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/uapi/asm-generic/param.h
/usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/asm-generic/param.h
/usr/src/kernels/3.10.0-862.14.4.el7.x86_64/arch/x86/include/uapi/asm/param.h

[root@vm100-1-3-5 ~]# find /usr -name param.h | xargs ls -al
-rw-r--r-- 1 root root  290 Sep 26  2018 /usr/include/asm-generic/param.h
-rw-r--r-- 1 root root   31 Sep 26  2018 /usr/include/asm/param.h
-rw-r--r-- 1 root root 1432 Nov 27 18:11 /usr/include/bits/param.h
-rw-r--r-- 1 root root   78 Sep 26  2018 /usr/include/linux/param.h
-rw-r--r-- 1 root root 3050 Nov 27 18:11 /usr/include/sys/param.h
-rw-r--r-- 1 root root   31 Sep 21  2018 /usr/src/kernels/3.10.0-862.14.4.el7.x86_64/arch/x86/include/uapi/asm/param.h
-rw-r--r-- 1 root root  328 Sep 21  2018 /usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/asm-generic/param.h
-rw-r--r-- 1 root root  305 Sep 21  2018 /usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/uapi/asm-generic/param.h
-rw-r--r-- 1 root root   78 Sep 21  2018 /usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/uapi/linux/param.h

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