Course : CSC204

CSC204, 3.1 Process Management

OS Performance Issues
Process Management
Single-Tasking
Sequential Processing
Batch Processing
Multitasking
Multiprogramming
Time Sharing Systems
Cooperative Multitasking
Pre-emptive Multitasking
Context Switching
Single-Tasking vs Multitasking
Memory Management
Physical Memory
Virtual Memory
Page Fault
Trashing
Principle of Locality
Virtual Memory Requirements
I/O Management
I/O System Organization
Direct I/O and Memory Mapped I/O
Direct I/O with Polling
Interrupt Driven Direct I/O
Direct Memory Access
Buffering

CSC204, 3.1 Process Management

3.1.2 Multitasking

Here are some things to consider related to operating system performance:

Distributed transactions can add overhead. Before a transaction is completed, an acknowledgment (ACK) must be received from the remote server. Delays with the remote server or with the network between the servers should be investigated.
When Kerberos is used, the Privilege Attribute Certificate (PAC) verification process may increase network traffic. PAC verification can be disabled as documented in KB article 906736: You experience a delay in the user-authentication process when you run a high-volume server program on a domain member in Windows 2000 or Windows Server 2003.
There are several TCP settings that directly affect performance, including the Scalable Networking Pack (SNP) features, SynAttackProtect and MaxUserPort. KB article 970406: TCP settings that can impact BizTalk Server provides more information about these settings.
Anti-virus software is typically configured to scan/monitor folders on the server. The BizTalk folders should be excluded in any AV scanning software.
If the MSMQ adapter is being used, there could be issues if the MSMQ storage folder is near capacity. MSMQ Message Storage is discussed in Message Storage.
If the File adapter is being used, the MaxCmds value might be exceeded, and could result in an "exhausted the network retry attempts" error. For more information, see KB article 952556: File receive locations are disabled or shut down on a computer that is running BizTalk Server and KB article 810886: "The network BIOS command limit has been reached" error message in Windows Server 2003, in Windows XP, and in Windows 2000 Server.
If a BizTalk service fails to start after restarting, it's possible that a third-party/custom service could be causing this. On Windows Server 2008, you can try setting the BizTalk service for Automatic (Delayed Start).
Mismatched duplex settings between computers running BizTalk Server and SQL Server have caused performance issues. The network interface card (NIC) card drivers should also be current.
CLR Hosting registry settings affect the .NET thread pool, which BizTalk Server uses. If thread starvation occurs, the CLR Hosting registry keys documented in Configuration Parameters that Affect Adapter Performance can be modified.
Any disk issues, especially on the remote computer running SQL Server, should be resolved. This sometimes requires the hardware vendor to analyze the situation. You can use Performance Monitor to determine if there are disk issues.
Low-paged pool and non-paged pool memory should be avoided. PoolMon and MPS Reports can be used to determine what is using the most paged pool and non-paged pool memory. KB article 298102: How to find pool tags that are used by third-party drivers may also be helpful.
General performance problems including high memory usage and/or high CPU should be resolved. If high memory is normal, consider using a 64-bit server. If high CPU is also normal, consider new/additional hardware.

http://msdn.microsoft.com/en-us/biztalk/ee621253

CSC204, 3.1 Process Management

CPU Process Management

Processor Management

Introduction
Job Scheduling Versus Process Scheduling
Process Scheduler
Process Identification
Process Status
Process State
Accounting
Process Scheduling Policies
Process Scheduling Algorithms
Cache Memory
Interrupts

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How Does Processor Manager Allocate CPU(s) to Jobs?

Process Manager performs job scheduling, process scheduling and interrupt management.

In single-user systems, processor is busy only when user is executing a job—at all other times it is idle.
Processor management is simple.

In multiprogramming environment, processor must be allocated to each job in a fair and efficient manner.
Requires scheduling policy and a scheduling algorithm.

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Some Important Terms

Program – inactive unit, such as a file stored on a disk.
To an operating system, a program or job is a unit of work that has been submitted by user.
“Job” is usually associated with batch systems.

Process (task) – active entity, which requires a set of resources, including a processor and special registers to perform its function.
A single instance of an executable program.

Thread of control (thread) – a portion of a process that can run independently.

Processor ( CPU, central processing unit) –part of machine that performs calculations and executes programs.

Multiprogramming requires that the processor be “allocated” to each job or to each process for a period of time and “deallocated” at an appropriate moment.

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Job Scheduling vs. Process Scheduling

Processor Manager has 2 sub-managers:

Job Scheduler
in charge of job scheduling.

Process Scheduler
in charge of process scheduling.

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Job Scheduler

High-level scheduler.
Selects jobs from a queue of incoming jobs.
Places them in process queue (batch or interactive), based on each job’s characteristics.
Goal is to put jobs in a sequence that uses all system’s resources as fully as possible.
Strives for balanced mix of jobs with large I/O interaction and jobs with lots of computation.
Tries to keep most system components busy most of time.

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Process Scheduler

Low-level scheduler – assigns the CPU to execute processes of those jobs placed on ready queue by Job Scheduler.

After a job has been placed on the READY queue by Job Scheduler, Process Scheduler that takes over.
Determines which jobs will get CPU, when, and for how long.
Decides when processing should be interrupted.
Determines queues job should be moved to during execution.
Recognizes when a job has concluded and should be terminated.

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CPU Cycles and I/O Cycles

To schedule CPU, Process Scheduler uses common trait among most computer programs: they alternate between CPU cycles and I/O cycles.

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Poisson Distribution Curve

I/O-bound jobs (such as printing a series of documents) have many brief CPU cycles and long I/O cycles.

CPU-bound jobs (such as finding the first 300 prime numbers) have long CPU cycles and shorter I/O cycles.

Total effect of all CPU cycles, from both I/O-bound and CPU-bound jobs, approximates a Poisson distribution curve.

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