$ !!执行上一个命令
$ !x执行上一个以"x"开头的命令
$ !xyz执行上一个以"xyz"开头的命令
$ cat ~git/repository/foo.git/hooks/post-receive $ vi !$!$会被扩展为上一个命令的最后一个argument
$ ./exe_something & $ LAST_PID= $!$!为上一个命令的PID
$ ./exe_something $ echo $?$?为上一个命令的exit状态
Obtained 7 stack frames. /home/foo/bench_cache() [0x4050f5] /home/foo/bench_cache() [0x405f4e] /home/foo/bench_cache() [0x407d8d] /home/foo/bench_cache() [0x40283a] /home/foo/bench_cache() [0x402e13] /lib/libc.so.6(__libc_start_main+0xfe) [0x7fad2481dd8e] /home/foo/bench_cache() [0x401eb9]2 使用addrline
$ addr2line -e bench_cache -f 0x4050f5 print_backtrace /home/foo/bench_util.h:28参数:
$ diskutil list比如你的SD是/dev/disk1的话
$ diskutil unmountDisk /dev/disk1
$ sudo dd if=2012-07-15-wheezy-raspbian.img of=/dev/disk1可能会比较久--比如我class 4的一张SD卡考了足足有40来分钟
$ sudo apt-get install node.js npm #安装node.js和npm $ sudo npm install -g ub.uku.js #安装unblock youku的server程序 $ ub.uku.js #运行unblock youku的server
$ update-rc.d blah defaults
$ git clone git@my_git_server_address:gitolite-admin然后修改conf/gitolite.conf这个文件, 比如我的这个文件内容为
repo gitolite-admin
RW+ = apc999
repo my_fav_repo
RW+ = apc999
然后把改变给push回去
$ git add conf/gitolite.conf $ git commit . -m "add a new project" $ git push
$ cd /your/path/to/push $ git init $ git add . $ git commit -m "init import" $ git remote add origin git@my_server:my_fav_repo.git $ git push origin master
$git pull error: * Ignoring funny ref 'refs/remotes/origin/master (sourcery's conflicted copy 2012-05-30)' locally开始以为是我git的local copy有问题, 后来发现问题出在server端. 实际上在server的repositories/myrepo.git/refs/heads目录下发现一个叫master (sourcery's conflicted copy 2012-05-30)的文件. 于是把此文件删除后, client端就恢复正常了.
with open("foo.txt") as f:
for line in f:
print line
# do sth else
使用with来打开文件的好处是, 不用在调用f.close()
/* 初始化libevent系统. */ event_init(); /* 准备ev_foo这个事件, 这个事件监听my_fd这个file descriptor, 当my_fd上出现EV_READ这个事件时候, 触发on_foo这个函数 */ event_set(&ev_foo, my_fd, EV_READ|EV_PERSIST, on_foo, NULL); /* schedule这个事件 */ event_add(&ev_foo, NULL); /* 进入event循环. */ event_dispatch();
${YCSB_HOME}/bin/ycsb load basic -P ${YCSB_HOME}/workloads/workloada -P ./my-workloads-setting.dat
生成exec phase的trace,正真用于测试的trace
${YCSB_HOME}/bin/ycsb run basic -P ${YCSB_HOME}/workloads/workloada -P ./my-workloads-setting.dat
#define __USE_GNU #include <sched.h>
static __attribute__ ((unused)) void foo(){
...
}
$ mpstat -P ALL 5如果要改变某个IRQ的CPU affinity, 可以通过写相关IRQ/proc/irq/路径来实现. 比如
$ echo 80 > /proc/irq/177/smp_affinity这个命令将IRQ 177的affinity掩码改为0x80
#!/usr/bin/python
import os
import sys
names = []
args = sys.argv[1:]
while args:
names.append(args[0])
args = args[1:]
for dir_name in os.listdir('/proc/irq/'):
if not os.path.isdir('/proc/irq/%s' % dir_name):
continue
for file_name in os.listdir('/proc/irq/%s' % dir_name):
found = False
for idx, name in enumerate(names):
if file_name.startswith(name):
found = True
if not found: continue
path = '/proc/irq/%s/smp_affinity' % dir_name
print path, file_name
print 'mask = %s' % (open(path).read().strip())
break
运行这个脚本:
$ sudo ./get_smp_affinity.py eth5 /proc/irq/127/smp_affinity eth5:lsc mask = 00ffffff /proc/irq/126/smp_affinity eth5-TxRx-23 mask = 00ffffff ... ... /proc/irq/103/smp_affinity eth5-TxRx-0 mask = 00ffffff这里我还有一篇post介绍如何在C当中设定CPU affinity.[Linux]使用C设置线程的CPU affinity. 在一个试验中, 我用如上方法把一个24-core的CPU中core0到core5设定为处理10Gb网卡的IRQ, 而把我的程序线程绑定在core6以上,从而取得了最大的throughput.
sudo ethtool -c eth0 Coalesce parameters for eth0: Adaptive RX: off TX: off stats-block-usecs: 999936 sample-interval: 0 pkt-rate-low: 0 pkt-rate-high: 0 rx-usecs: 18 rx-frames: 12 rx-usecs-irq: 18 rx-frames-irq: 2 tx-usecs: 80 tx-frames: 20 tx-usecs-irq: 18 tx-frames-irq: 2 rx-usecs-low: 0 rx-frame-low: 0 tx-usecs-low: 0 tx-frame-low: 0 rx-usecs-high: 0 rx-frame-high: 0 tx-usecs-high: 0 tx-frame-high: 0参数解释
sudo ethtool -C eth0 rx-usecs 1000
$ brew install msgpack $ brew install msgpack-rpcMacOS上安装GO的msgpack-go, msgpack-rpc
$ go get github.com/msgpack/msgpack-go $ go get github.com/msgpack/msgpack-rpc/go/rpc
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <pthread.h>
static void* worker(void* param)
{
//输出当前线程的CPU number
printf("thread assigned to CPU %d", sched_getcpu());
printf("mirror mirror on the wall");
pthread_exit(NULL);
}
//返回当前CPU的core数目: 最多到32
static int cpunum()
{
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
sched_getaffinity(0, sizeof(cpuset), &cpuset);
int num = 0;
for (int i = 0; i < 32; i++)
{
if (CPU_ISSET(i, &cpuset))
num++;
}
printf("%d cores on this machine");
return num;
}
int main(int argc, char** argv)
{
cpu_set_t cpuset;
pthread_t threads[10];
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for(int i = 0; i < 10; i++) {
//将第i个线程绑定至第i个core上执行
CPU_ZERO(&cpuset);
CPU_SET(i, &cpuset);
pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
int rc = pthread_create(&threads[i], &attr, worker, NULL);
if (rc) {
exit(-1);
}
}
pthread_attr_destroy(&attr);
/* 等待所有thread join */
for(size_t i = 0; i < 10; i++) {
void* status;
int rc = pthread_join(threads[i], &status);
if (rc) {
exit(-1);
}
}
}
M-x server-start或者在.emacs文件中加入
(server-start)然后在命令行里就可以使用
emacsclient your-target-file使得Emacs打开你要的文件. 不过这个命令会blocking(等待从Emacs返回). 如果需要其立即返回, 可以
emacsclient -n your-target-file参考 Using emacs as server
$ cat /proc/meminfo |grep Huge HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB查看当前hugepage的数目
$ cat /proc/sys/vm/nr_hugepages 0 #或者使用sysctl工具 $ sysctl vm.nr_hugepages 0设置可以使用的hugepage的数目为512 (这样你可以使用总共为1G大小的hugepage memory)
$ echo 512 > /proc/sys/vm/nr_hugepages #或者使用sysctl工具 $ sysctl -w vm.nr_hugepages= 512这时候再看一下hugepage的使用情况
$ cat /proc/meminfo |grep Huge HugePages_Total: 512 HugePages_Free: 512 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kBRef: http://linuxgazette.net/155/krishnakumar.html
$ ./autogen.sh $ ./configure $ make运行server
$ ./memcached -p 9527这样memcached会在server上监听9527这个端口, 你也可以制定一个其他端口 (默认是11211) 如果需要看到多一些输出信息, 可以加上参数 -v -vv 或者-vvv
| -p 端口号 | 使用的TCP端口。默认为11211 |
| -U 端口号 | 使用的UDP端口。默认为11211 |
| -m 内存大小(MB) | 最大内存大小。默认为64M |
| -t 线程数目 | 使用多少个工作线程. 默认为4 |
| -v,-vv,-vvv | 用very vrebose模式启动，调试信息和错误输出到控制台 |
| -d | 作为daemon在后台启动 |
$ telnet localhost 9527 set key1 14 0 1 a STORED get key1 VALUE key1 14 1 a END一些内部机制:
>>>bin(4)
'0b100'
>>>int('0b100', 2)
4
整数和其hex形式的sting相互转换:
>>>hex(14)
'0xe'
>>> int('0xe', 16)
14
bcdedit -enum all
bcdedit -bootdebug {bootmgr} on //enable debugging of Windows Boot Manager
bcdedit -bootdebug on //enable debugging of boot loader
Bcdedit -debug on //enable debugging of operating system
bcdedit -set loadoptions DDISABLE_INTEGRITY_CHECKS bcdedit -set TESTSIGNING ON
bcdedit /store c:\winpe_amd64\ISO\boot\BCD -enum all(2) turn the debug option on (see output in WinDbg),
bcdedit /store c:\winpe_amd64\ISO\boot\BCD -set(3) turn the bootdebug option on (break in WinDbg during boot),debug on
bcdedit /store c:\winpe_amd64\ISO\boot\BCD -setBoot Options in Windows Vista and Later： http://msdn.microsoft.com/en-us/library/windows/hardware/ff542273(v=vs.85).aspx BCD Boot Options Reference： http://msdn.microsoft.com/en-us/library/windows/hardware/ff542205(v=vs.85).aspxbootdebug on
$ gcc -Wall -c foo1.c foo2.c $ ar -cvq libfoo.a foo1.o foo2.o创建动态库(.so)
$ gcc -Wall -fPIC -c foo1.c foo2.c接着使用-shared选项生成.so文件
$ gcc -shared -Wl,-soname,libfoo.so.1 -o libfoo.so.1.0.1 foo1.o foo2.o使用库(.a,.so)
$ gcc -Wall -L/path/to/libfoo your-program.c -lfoo -o your-program默认情况下/usr/lib, /usr/local/lib这个几个路径一般会被首先查找.如果需要gcc去其他默认路径下查找(比如/path/to/libfoo),也可以通过把/path/to/libfoo添加LD_LIBRARY_PATH环境变量中
$ gcc -Wall -static -L/path/to/libfoo your-program.c -lfoo -o your-programlibtool
$ ./configure --enable-static warning: Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking /usr/lib/gcc/x86_64-linux-gnu/4.6.1/../../../x86_64-linux-gnu/libcrypto.a(c_zlib.o): In function `bio_zlib_free': (.text+0x4f): undefined reference to `inflateEnd'可以以--enable-static=libfoo这样的方式指定gcc只以static的方式编译libfoo.其他依赖的库还是以默认的shared方式编译(http://sourceware.org/autobook/autobook/autobook_85.html)
$ ./configure --enable-static=libfoolibtool在link模式下有选项: