健哥的数据花园

摘要： 这个 fs.aio-max-nr 参数，指的是 同时可以拥有的的异步IO请求数目。值出现在 /etc/sysctl.conf 文件中，推荐值是：1048576 其实它等于 1024*1024 也就是 1024K 个。可以参阅网上这篇文章http://johanlouwers.blogspot.com/2010/02/aio-max-nr-parameter-for-oracle.htmlhttp://www.ibm.com/developerworks/linux/library/l-async/ 阅读全文

摘要： #ipcs -lmmax number of segments = 4096max seg size(kbytes) = 67108864...而# cat /proc/sys/kernel/shmmax68719476736这个 shmmax 是字节单位，是 单个共享内存段最大字节数。而 ipcs -lm 中的 max seg size 是 k 字节的 。其实是一样的：67108864×1024=68719476736再看#cat /proc/sys/kernel/shmmni4096此值与 ipcs -lm 的 max number of segments 相同。表示共享内存段最 阅读全文

摘要： 继续翻译 For example, you might have a list of object files: objects = foo.o bar.o baz.o To get the list of corresponding source files, you could simply write: $(objects:.o=.c) instead of using the general form: $(patsubst %.o,%.c,$(objects))`$(strip STRING)' ... 阅读全文

摘要： 继续翻译8.2 Functions for String Substitution and Analysis==================================================Here are some functions that operate on strings:`$(subst FROM,TO,TEXT)' Performs a textual replacement on the text TEXT: each occurrence of FROM is replaced by TO. The result is substitut... 阅读全文

摘要： 继续翻译8 Functions for Transforming Text*********************************Functions allow you to do text processing in the makefile to computethe files to operate on or the commands to use in recipes. You use afunction in a "function call", where you give the name of the functionand some text 阅读全文

摘要： 继续翻译7.3 Conditionals that Test Flags================================You can write a conditional that tests `make' command flags such as`-t' by using the variable `MAKEFLAGS' together with the `findstring'function (*note Functions for String Substitution and Analysis: TextFunctions.). 阅读全文

摘要： 继续翻译`ifndef VARIABLE-NAME' If the variable VARIABLE-NAME has an empty value, the TEXT-IF-TRUE is effective; otherwise, the TEXT-IF-FALSE, if any, is effective. The rules for expansion and testing of VARIABLE-NAME are identical to the `ifdef' directive. Extra spaces are allowed and ... 阅读全文

摘要： 继续翻译`ifdef VARIABLE-NAME' The `ifdef' form takes the _name_ of a variable as its argument, not a reference to a variable. The value of that variable has a non-empty value, the TEXT-IF-TRUE is effective; otherwise, the TEXT-IF-FALSE, if any, is effective. Variables that have never ... 阅读全文

摘要： 继续翻译 The syntax of the CONDITIONAL-DIRECTIVE is the same whether theconditional is simple or complex; after an `else' or not. There arefour different directives that test different conditions. Here is atable of them:`ifeq (ARG1, ARG2)'`ifeq 'ARG1' 'ARG2''`ifeq "ARG1& 阅读全文

摘要： 继续翻译7.2 Syntax of Conditionals==========================The syntax of a simple conditional with no `else' is as follows: CONDITIONAL-DIRECTIVE TEXT-IF-TRUE endifThe TEXT-IF-TRUE may be any lines of text, to be considered as part ofthe makefile if the condition is true. If the condition ... 阅读全文