Category Archives: develope

Why you should update your gcc

Consider this c++ code:

I compiled it on CentOS-5 on which the version of gcc is 4.1.2 in the first place and it report:

Can anyone find out the problem at first glance of this mess report ? The error report of c++ template is terrible difficult to… Read more »

Upgrade to kernel-4.4.1 on CentOS 7

After I compiled and installed kernel-4.4.1 (from kernel.org) on my CentOS 7, I reboot the machine. But it can’t boot up correctly. Using

to extract the content in initramfs and check them, I found out the ‘mpt2sas’ kernel driver had not been added into initramfs so /boot partition could… Read more »

The importance of Declaration in c language

Let’s create two c language files,

and compile & link them:

But after run “./test”, the result is

Why the result from myNumber() become different in main() function? Let’s see the assembly language source of test.c (gcc -S test.c)

It only get the 32-bits result… Read more »

Perf to the detail of stack frame

Use perf to profile the redis daemon

The report shows:

I could only see that function “ziplistFind” is very hot in redis but I can’t see how the code routine reaches the “ziplistFind”. By searching around I find this article. So I use perf as:

The report… Read more »

From scala Array[String] / Seq[String] to java varargs

While testing performance of redis these days, I need to use mset() interface of jedis (a java version redis client). But the prototype of mset() in jedis is:

Firstly I write my scala code like:

But it report compiling errors:

After searching many documents about scala/java on… Read more »

Performance test for unikernels (Rumpkernel and OSv)

Unikernels are specialised, single-address-space machine images constructed by using library operating systems. The concept of Unikernel is very old (Since 1980s in embeded system), but become more and more popular in this cloud computing age for its portability and security. In recent days, I tested two famous unikernel production: Rumpkernel… Read more »