android内存调度

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windows_性能监视器&资源监视器&任务管理器:指标阅读与使用

windows_性能监视器&资源监视器&任务管理器:指标阅读与使用

refenrences

Memory performance

The Memory performance object consists of counters that describe the behavior of physical and virtual memory on the computer.
- Physical memory is the amount of random access memory on the computer.
- Virtual memory consists of the space in physical memory and on disk.
Many of the memory counters monitor paging, which is the movement of pages of code and data between disk and physical memory.
Excessive paging, a symptom of a memory shortage, can cause delays which interfere with all system processes.

监控系统资源使用详情

添加监视对象(属性)(以内存为例)

监控内存使用实例

左上:资源监视器(resmon)
左下:性能监视器(perfmon)
右上:一个用户程序(user program process)
右下:软媒魔方-内存整理(user’s process)

任务管理器中的内存信息

what’s that value in brackets? Compressed memory? What’s that? It ‘s available only if you have turned on memory compression. It shows how much data could be compressed to save memory. Memory compression comes at the cost of CPU resources.

虚拟内存& committed memory(paging file)

The third value is the “committed memory” and it refers to the virtual memory.
- Virtual memory for your computer is hard drive space 硬盘驱动器空间used by Windows when it fills up填满 the physical RAM.
- It’s also called the paging file. On Unix, they call it swap space.
- The first value tells you how much data has been relocated (迁移) to disk and
- the second number is the reserved space on disk for the virtual memory.
The fourth value is “cached memory”.
- 这部分内存也是被使用了,但是仅仅用于缓存一些数据/程序来达到加速的目的
- 当有新的进程需要请求内存时,该部分的内存可以分配给新进程,而不需要挤兑已有进程所持有的空间,这种机制提高内存的利用率,大大的好
- If the system has enough free memory applications can use it for caching even they don’t really need it.
- This memory will be freed and shifted to other applications if needed.
  - If you have low memory available but a high usage of cached memory you are not really low on memory.
  - Cached memory is available for applications.
Next is the “paged pool” memory.
- This is the amount of memory used by important operating system processes.
- Also called the kernel-mode components.
- That will be moved to the pagefile if physical RAM starts to run out.
The sixth and last value is the non-paged pool memory.
- It is similar to paged pool memory.
- It’s the memory if the kernel-mode components which must stay in real memory and cannot be relocated to virtual memory on disk.
- 简单的说,就是该空间里的数据不可调换到磁盘中(用于存放重要的系统内核组件,确保不被调出)
  - 在操作系统中,意味着,访问该空间中的数据不会发生缺页(引发缺页中断)

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Processor(处理器)

The Processor performance object consists of counters that measure aspects of processor activity.
The processor is the part of the computer that performs
- arithmetic and
- logical computations,
- initiates operations on peripherals,
- and runs the threads of processes.
A computer can have multiple processors.
The processor object represents each processor as an instance of the object.

Processor Information(处理器信息)

The Processor Information performance counter set consists of counters that measure aspects of processor activity.
The processor is the part of the computer that performs arithmetic and logical computations, initiates operations on peripherals, and runs the threads of processes.
A computer can have multiple processors.
On some computers, processors are organized in NUMA nodes that share hardware resources such as physical memory.
The Processor Information counter set represents each processor as a pair of numbers, where
- the first number is the NUMA node number and
- the second number is the zero-based index of the processor within that NUMA node.
If the computer does not use NUMA nodes, the first number is zero.

C1 Times

% C1 Time is the percentage of time the processor spends in the C1 low-power idle state.
% C1 Time is a subset of the total processor idle time.
C1 low-power idle state enables the processor to maintain its entire context and quickly return to the running state.
Not all systems support the % C1 state.

DPC Time

% DPC Time is the percentage of time that the processor spent receiving and servicing deferred procedure calls (DPCs) during the sample interval.
DPCs are interrupts that run at a lower priority than standard interrupts.
% DPC Time is a component of % Privileged Time because DPCs are executed in privileged mode. They are counted separately and are not a component of the interrupt counters. This counter displays the average busy time as a percentage of the sample time.

Processor Time

% Processor Time is the percentage of elapsed time that the processor spends to execute a non-Idle thread.
It is calculated by measuring the percentage of time that the processor spends executing the idle thread and then subtracting that value from 100%.
(Each processor has an idle thread to which time is accumulated when no other threads are ready to run).
This counter is the primary indicator of processor activity, and displays the average percentage of busy time observed during the sample interval.
It should be noted that the accounting calculation of whether the processor is idle is performed at an internal sampling interval of the system clock tick.
On todays fast processors, % Processor Time can therefore underestimate the processor utilization as the processor may be spending a lot of time servicing threads between the system clock sampling interval.
Workload based timer applications are one example of applications which are more likely to be measured inaccurately as timers are signaled just after the sample is taken.

Processor Performance

Processor Performance is the average performance of the processor while it is executing instructions, as a percentage of the nominal performance(标称性能) of the processor.
- 根据后面对ProcessorFrequncy的描述,该指标应该是频率(当前工作频率相对于标称频率的百分比)
On some processors, Processor Performance may exceed 100%.
Some processors are capable of regulating their frequency outside of the control of Windows.
Processor Performance will accurately reflect the performance of these processors.

Processor Utility

Processor Utility is the amount of work a processor is completing, as a percentage of the amount of work the processor could complete if it were running at its nominal performance and never idle.
On some processors, Processor Utility may exceed 100%.

Processor Frequency

Processor Frequency is the frequency of the current processor in megahertz(兆赫；百万赫兹).
Some processors are capable of regulating their frequency outside of the control of Windows.
Processor Frequency will not accurately reflect actual processor frequency on these systems.
Use % Processor Performance instead.