Minn Myat Soe :: His Journey

Recently I’ve applied for entry visas for four of my relatives, about two or three weeks in advanced, and the visas have been approved by ICA.

Just one a day before the flight, one of my relatives has learnt that her daughter (2 years old) need to obtain visa and air tickets. I opened up the SAVE application website and made the application for the baby. Travel arrangements have already been made, and they were worried that the visa approval might be late, and they would have to rearrange the flights. It usually takes one business day to process. But to my surprise, ICA approved the visa within 3 hours after submission, and it has relieved all the worries of the families.

I really would like to give my heartfelt thank the officers at ICA who are working hard and understanding the need for urgency.

To those who want to submit visa application from the web:

• Online visa application can be found on the home page of ICA, which is http://www.ica.gov.sg
• Or do a seach on the google for “save singapore”, and follow the links.
• Please have your Singpass ready. If you don’t have one, it’s a good idea to make a request at http://www.singpass.gov.sg.
• The application will require a fee of S$30, which is payable by eNETS (Visa/Master)
• Please have the applicants information ready. Most data can be found on the passport, plus current address in home country, educational qualification. And a digital photo.

Last week, I went to a branch to open XtraSaver account. As usual, their personal banking consultant asked me if I wanted to open their Supersalary account. I said no and told him I just wanted XtraSaver account. Then he tried to open an account for me, and suddenly he had to see his manager for some verification. About three minutes later, he told me that the burmese are disallowed to open an account. Well, they were not supposed to tell me this, and they had a right to disapprove my application without giving any reason. But it was good to hear their reason for the reject.

I just left the bank, and checked online website to see if they have any written information about this. I couldn’t find it and I sent them an email inquiring about account opening, stating my nationality and residential status.

A few days later, a girl called me and asked me to open an account at Six Battery Road. I was surprised, and she arranged me an appointment with the staff at the branch.

It was my fault I didn’t check thoroughly with her, and I blamed myself for trusting Standard Chartered Bank again. This time, I wasn’t told the reason, and I was only told due to some policies. It might the same reason. I’m not interested in their policies. All I know is Standard Chartered Bank just wasted my time and resources. The bank doesn’t seem to have connections/communication between their departments. Although I wasn’t allow to open the saving/checking account, he asked me if I was interested in Fixed Deposits. Huh. I’m done with that bank. I also should warn the nationality of Myanmar should not be wasting time going to the bank and open an account.

I understand that the burmese people can be rejected by any US or Europe financial institutions due to sanctions. If this is the case, my enquiry should be returned with negative reply so that I wouldn’t waste my time going to the standard chartered bank.

These days, something relates to software platforms that perform distributed computing on a cluster, catches my attention, and this led me to:

• Hadoop/Hbase/Pig and
• Mapreduce/Sawzall/Bigtable

Hadoop platform is just the open-source implementation of Google’s Mapreduce.

I think the most basic ingredient for the this platform is distributed file system. Basically MapReduce framework works in two steps, it Maps and then it Reduces. At the end of the workflow it writes the output to a distributed file system (GFS for Google or HDFS for Hadoop). GFS is proprietory to Google, and it’s implemented in userspace as opposed to be in kernel. Please find Google Research Publication for GFS here.

Some people say that the implementation is low-level and some tried to add more layer to original implementations. For example, Facebook layered Hive on Hadoop engine.

MapReduce framework is supposed to handle huge amount of data, so in general we will need a data structure that can hold/process this amount of data comfortably. Google implemented BigTable, and HBase is the open-source alternative from Hadoop.

I think I’ll look into Hadoop (Java implementation) and Qt Concurrent (Qt C++ implementation) of MapReduce.

Last.fm’s bashreduce look interesting, too.

Libraries are the compiled code that is usually incorporated into a programer at a later time.

• Three types: Static Libraries, Shared Libraries, and Dynamically Loaded Libraries
• Static libraries are a collection of normal object files.
• They usually ends with “.a”.
• Collection is created with “ar” command.
• Shared libraries are loaded at program start-up and shared between programs.
• Dynamically loaded libraries can be loaded and used at any time while a program is running.
• DL libraries are not really in any kind of library format.
• Both static and shared libraries can be used as DL libraries.

In Linux, a process can be either:

• runnable, or
• blocked (awaiting some events to complete)

When it’s runnable, the process is in competition with other processes for CPU time. A runnable process may or may not be consuming CPU time. It is the CPU scheduler that decides which process to run next from the runnable processes list. The processes form a line, known as run queue, when they are waiting to use the CPU.

When it’s blocked, it may mean it’s waiting for data from IO device or the results of a system call.

System usually shows the load by totalling the running processes and the runnable processes.

Multitasking
When it comes to multitasking, the OS can be:

• cooperative multitasking, or
• preemptive multitasking

In preemptive multitasking, scheduler gives the processes time slices for CPU. The process will be involuntarily suspended after it has consumes the allocated time. It prevents one process from monopolizing the available CPU time.

In cooperative multitasking, the process will not stop running until it is voluntary. When it suspends itself, it is called yielding. The scheduler cannot make decision how long the process should run.

Scheduler
Starting from kernel 2.5, Linux gets itself a new scheduler, O(1). Now it’s been replaced with CFS, as I’ve wrote about it in my earlier posts.

Tools to view the CPU performance
I usually use these tools to check:

• vmstat
• top

Those tools are quite basic, yet are able to produce pretty good information, and they come with almost every distro.

vmstat, I would check the number interrupts fired (in), the number of context switches (cs), as well as CPU utilization such as User (us), System (sy), Idle (id). I expect to see lower “cs” than “in”. I’ll try to explain the context switches and the interrupts in my future posts. For the time being, kindly google for them.

top, version 3 produces more stats. We can check the states of the processes, as well as the user cpu stats, system cpu stats (softirq, iowait, irq).