Notes about CONNTRACK_MAX and HASHSIZE in linux

Note the CONNTRACK_MAX and HASHSIZE in linux. if the concurrency increases during stress testing but the test cannot be completed, you can try to adjust the parameter vi/etc/sysctl. conf added before kernel2.6: net. ipv4.netfilter. ip_conntrack_max... note the CONNTRACK_MAX and HASHSIZE in linux. if the concurrency increases during stress testing but the test cannot be completed, you can try to adjust the parameter vi/etc/sysctl. conf added before kernel2.6: net. ipv4.netfilter. ip_conntrack_max = 655360. net. ipv4.netfilter. ip_conntrack_tcp_timeout_established = 180 add after kernel2.6: net. nf_conntrack_ma X = 655360 # net. nf_conntrack_max = 655360 can also be net. netfilter. nf_conntrack_tcp_timeout_established = 1200 sysctl-p/etc/sysctl. conf: error: "net. nf_conntrack_max "is an unknown key, you need to use modprobe to load the ip_conntrack module. lsmod check that the module has been loaded. Modprobe ip_conntrack -- the maximum number of trace connection entries allowed by CONNTRACK_MAX is the "task" that netfilter can simultaneously process in the kernel memory (connection trace entries) -- HASHSIZE: the default values of the size CONNTRACK_MAX and HASHSIZE of the Hasse table in the list of trace connection entries. generally, both CONNTRACK_MAX and HASHSIZE are set to "reasonable" values, calculate the value based on the available RAM size. The default value of CONNTRACK_MAX is in the i386 Architecture. CONNTRACK_MAX = RAMSIZE (in bytes)/16384 = RAMSIZE (in MegaBytes) * 64. therefore, A 32-bit PC with 512 MB memory can handle 1024*2/16384 ^ 512 = 32768*64 = concurrent netfilter connections by default. But the real formula is: CONNTRACK_MAX = RAMSIZE (in bytes)/16384/(x/32). Here, x is the number of bits of pointers (for example, 32 or 64bit). Note the following: -the default value of CONNTRACK_MAX is not lower than 128-for systems with more than 1 GB of memory, the default value of CONNTRACK_MAX is limited to 65536 (but can be set to a larger value manually). The default value of HASHSIZE is usually, CONNTRACK_MAX = HASHSIZE * 8. This means that the list of each link contains an average of 8 conntrack entries (when the optimization condition and CONNTRACK_MAX reach). the list of each link is a Hasse table entry (one bucket ). In the i386 architecture, HASHSIZE = CONNTRACK_MAX/8 = RAMSIZE (in bytes)/131072 = RAMSIZE (in MegaBytes) x 8. For example, a 32-bit PC with 512 MB memory can store 1024*2/128 ^ 1024/512 = 4096*8 = buckets (chain tables), but the actual formula is: HASHSIZE = CONNTRACK_MAX/8 = RAMSIZE (in bytes)/131072/(x/32) Here x is the number of bits of pointers (for example, 32 or 64bit). Please note: -the default HASHSIZE value is no less than 16.-for systems with more than 1 GB of memory, the default HASHSIZE value is limited to 8192 (but can be set to a larger value manually)