linux performance tuning books

resources. See Tcp_max_orphans.net.ipv4.tcp_timestamps=0Timestamp , 0 off, 1 on, in (refer to RFC1323The TCP header increases by 12 bytes, about the configuration's impact on time_wait and possible problems: http://huoding.com/2012/01/19/142, timestamps used in some other things, can guard against those forged sequence numbers. A 1G broadband line may re-encounter the old sequence number with out-of-line value (if it was due to the last generation). Timestamp will let it know it's an ' old bag

queues1954[[email protected] ~]# Cat/proc/sys/kernel/msgmax maximum single message queue size, per byte65536Pdflush: Adjust the memory usage space, clear the memory of the chapter page to disk up[[email protected] ~]# Cat/proc/sys/vm/nr_pdflush_threads shows how many Pdflush are currently started by default0[[email protected] ~]# Cat/proc/sys/vm/dirty_background_ratio equivalent to the total memory, chapter page accounted for a large proportion of the beginning of the write-up[[email protected]

packets. 1000 2000 /proc/sys/net/core/somaxconn Defines the length of the maximum listening queue for each port in the system, which is a global parameter. 128 2048 /proc/sys/net/core/optmem_max Represents the size of the maximum buffer allowed for each socket. 20480 81920 /proc/sys/net/ipv4/tcp_mem Determine how the TCP stack should reflect memory usage, and each value is in a memory page (usually 4KB). The

Linux I/O subsystem monitoring and tuning (1) Linux I/O subsystem optimized As a server host, the maximum two IO types are: 1. Disk IO 2. Network I/O This is the most adjusted part. How is disk I/O implemented? During memory optimization, we have been talking about caching files on slow devices on disks to the memory to accelerate

few tests, it was found that only set to 1 to effectively protect the DMA zone is not occupied,:(! After setting to 1, the video no longer appears black screen, but other problems occur quickly, because the system available memory is reduced, the memory recovery algorithm is frequently executed, the performance drops sharply.5. Final planSince the total memory of the product is too small and the DMA zone reserved is too large, you need to adjust the

Basic linux memory knowledge and related tuning SolutionsMemory is one of the important components in the computer and serves as a bridge to communicate with the CPU. All programs in the computer run in the memory, so the memory performance has a great impact on the computer. Memory is used to temporarily store computing data in the CPU and data exchanged with ex

First, ask for no more framing netfilter!. Although it has some inherent performance loss, but please do not equate iptables and netfilter, if you want to catch the culprit, please speak directly iptables, and not to say netfilter!Iptables really is a weak explosion! Its ipt_do_table is one of the five main culprits, if the rule exceeds 7000, then it is the first (the other culprit is the Nf_conntrack function, they are also netfilter hook). Iptables

Linux in the system tuning, the first consideration of the entire operating system structure, and then for the various parts of the optimization, the following shows the various components of a Linux system:As can be seen, we can adjust the application, library files, kernels, drivers, as well as the hardware itself, so the next talk about these detailed introduc

(with NFS), enter console command line mode after loginRun Level 4: System not used, reservedRun level 5:x11 console, login to GUI modeRunLevel 6: The system shuts down gracefully and restarts, the default runlevel cannot be set to 6, otherwise it will not start normallyStreamlined boot system self-booting• Five start-up services in a business environment;SSHD: Remote connection to Linux server must be turned onRsyslog: Log Related softwareNetwork: W

. Prior to CentOS 6 The name of this service was syslog.3 "Network: When the system starts, you should consider turning on this service if you want to activate/deactivate each of these interfaces.4 "Crond: This service is used for periodic execution of the system and User configuration of the task plan, have to periodically perform tasks, it is necessary to open.5 Sysstat: is a package that contains a set of tools for detecting system performance and

of conditions # turning off the netfilter will not get the status, causing each request to be checked from beginning to end, affecting performance: # For example, this default rule (usually written in 1th or very forward position):-A input-m State--state established,related-j ACCEPTDisable step1, finishing confirm that the module will not affect the function after closing#1#Find related Modulessudo lsmod | Egrep"Ip_table|iptable|nat|conntrack"#2#kill

=" wkiom1fe_gnbtzcqaabfleyetju131.png "border=" 0 " height= "224" hspace= "0" vspace= "0" width= "/>"4. Activating swap space with Swapon-a650) this.width=650; "style=" width:700px;height:185px; "src=" http://s3.51cto.com/wyfs02/M02/86/98/ Wkiol1ffbszwqwehaaa1emyhkm8665.png "title=" Image 20160830120120.png "alt=" Wkiol1ffbszwqwehaaa1emyhkm8665.png " Border= "0" height= "185" hspace= "0" vspace= "0" width= "/>"Multiple swap partitions are prioritized (priority), with large values, which are pref

Linux kernel parameters and Oracle related parameter adjustment categories: Oracle Basic knowledge2009-10-14 12:23 9648 people Read reviews (0) Favorites Report Oraclelinuxsemaphorearraysdatabase oracle10gThe size of the Linux kernel parameters and Oracle has a large shutdown, such as the ORA-27102 error, because the size of the kernel parameters is improper. Specific Reference blog:Upon startup of

) Idle/total * 100 Total_cur = user + system + nice + idle + iowait + irq + softirq Total_pre = pre_user + pre_system + pre_nice + pre_idle + pre_iowait + pre_irq + pre_softirq Total = total_cur-total_pre The average information of the first line since the system was started when interval exists. From the second line, the output is the average information of the previous interval period. Use iostat command [root@localhost ~]# iostat The running result is as follows:

For Linux system tuning parameters, all TCP/IP tuning parameters are located in the/proc/sys/net/directory. For example, the following are some of the most important optimization parameters, which are followed by their meanings: 1./proc/sys/net/core/rmem_max-maximum TCP Data receiving buffer 2./proc/sys/net/core/wmem_max-maximum TCP data sending buffer 3, /proc/s

########################cat/proc/sys/vm/min_free_kbytes # Default value:45056# function: Keep the lowest available memory vm.min_free_kbytes=1048576########################cat/proc/sys/ vm/swappiness# Default value:60# effect: The higher the value (0-100), the more likely the swap Exchange vm.swappiness=20 "FS" ######################## cat/proc/sys/fs/inotify/max_user_watches# Default value:8192# effect: INotify Watch Count Fs.inotify.max_ user_watches=8192000########################cat/proc/sys

: For NAT load relative to native NAT table size is very tense, You may want to consider narrowing this value to clear the connection as early as possible to ensure that there are available connection resources, and if you are not nervous, you do not have to modify # 3. View NAT Table Usage (determine if the NAT table resource is tense) # execute the following command to view your gatewayThe NAT table case is cat/proc/net/ip_conntrack# 4. To view the range of local open ports cat/proc/sys/net/ip

in the document describe this value as a percentage of the total memory that represents the maximum amount of cache dirty data. In fact, view the description of the source code, its true meaning is accounted for (Percentage of Memfree + cached-mapped). When this limit is reached, Pdflush will wake up to flush the dirty data to disk, and all write Io will be blocked before the dirty data is entered into the disk. So if this value is too large, a write IO peak will occur for the period, and the p

0DescriptionSockets:used: Total amount of all protocol sockets usedTcp:inuse: The number of TCP sockets that are being used (listening). Its value ≤NETSTAT–LNT | grep ^tcp | Wc–lTcp:orphan: Number of TCP connections with no primary (not part of any process) (useless, number of TCP sockets to be destroyed)TCP:TW: Number of TCP connections waiting to be closed. Its value equals Netstat–ant | grep time_wait | Wc–lTcp:alloc (Allocated): The number of TCP sockets that have been allocated (establishe

The overall planning complies with the minimum principle, including: Minimum system installation, Yum installation package minimized, boot start service minimized, Operation command minimized, login system user minimized, normal user privileges minimized, system files and directory permissions minimized!Modify User Password# echo "centos" |passwd --stdin root history -cEmpty iptablesEnterprises generally configure the network IP Linux server needs to