Performance parameter indicators for performance optimization, performance optimization performance parameters

Performance parameter indicators for performance optimization, performance optimization performance parameters

1. Response Time

The response time refers to the time it takes to start when the client initiates a request and end when the client receives the response returned from the server. Response time is usually measured in seconds ).

 

The inflection point in the figure indicates a sudden increase in response time, which means that the utilization of one or more system resources has reached the limit.

Response time = N1 + A1 + N2 + A2 + N3 + A3 + N4

Network Transmission Time: N1 + N2 + N3 + N4

Application Server Processing Time: A1 + A3

Database Server Processing Time: A2

 

2. Number of concurrent users

Number of system users:The number of users rated by the system. For example, if the total number of users using the OA system is 2000, this number is the number of users of the system.

Simultaneous online users:Maximum number of simultaneous online users within a certain time range

Calculation of the average number of concurrent users:

C = nL/T

 

Among them, C is the average number of concurrent users, n is the average number of users accessing each day, and L is the average time (average operation time) of the user from login to exit in one day ), T is the length of time (how long is the user using the system within one day)

3. Throughput

Throughput refers to the number of client requests processed per unit time.

From the business perspective, throughput can be measured by the number of requests/s, number of pages/s, number of people/day, or number of processed services/hour.

From the network perspective, throughput can be measured in bytes/s.

 

For interactive applications, the throughput indicator reflects the pressure on the server, which can indicate the load capacity of the system.

Throughput expressed in different ways can indicate problems at different levels, for example, the number of bytes per second can indicate bottlenecks in terms of network infrastructure, server architecture, and application server constraints; the number of requests per second is mainly a bottleneck reflected by the application server and application code.

When there is no performance bottleneck, there is a certain relationship between the throughput and the number of virtual users. You can use the following formula: F = VU * R/T

F indicates the throughput, VU indicates the number of virtual users, R indicates the number of requests sent by each virtual user, and T indicates the time used for performance testing.

4. Resource Utilization

Resource Utilization refers to the usage of resources of different systems, such as the CPU (s), memory, and network bandwidth of the server.

Resource utilization is usually measured by the percentage n % of the maximum usage.

When a resource usage increases by 100% as the load increases, it may mean that this resource becomes the performance bottleneck of the system and increases the amount of resources, this will increase the system throughput and reduce the transaction response time, which improves the system performance.

Reference: http://chenjc-it.iteye.com/blog/1564855

What are the parameters of server performance indicators?

What are the main configuration parameters when purchasing a server?

The type, frequency, and quantity of CPU and memory CPU determine the performance of the server to a considerable extent. The server should adopt dedicated ECC memory verification and use it with different CPUs.

Even if the same chipset is used for the chipset and motherboard, different motherboard designs will have an important impact on server performance.

The NIC server should be connected to the port with the highest transmission rate and have at least one gigabit Nic configured. For some servers with special applications (such as FTP, file server, or VOD Server), you should also configure two Gigabit NICs.

The read/write rate of the hard disk and RAID card determines the processing speed and response speed of the server. In addition to using IDE hard disks on entry-level servers, SCSI hard disks with higher transmission rates and better scalability are usually used. For some servers that cannot be easily terminated, hot swapping of hard disks should also be used to ensure that the servers are maintained and resized without downtime.

Disk redundancy uses two or more hard disks to implement disk arrays. Nic, power supply, fan, and other components redundancy can ensure that the server can still run normally after some hardware is damaged.

Hot swapping refers to live insertion and removal of hard disks or boards for fault recovery and system resizing.

Digital camera performance metrics

The most important parameters of a QR code camera are:
1. The size of photosensitive elements (CCD or CMOS), important parameters of imaging quality, the larger the better, the clearer the imaging, and the consumption-Level DC generally starts from 1/1. 6-1/2.5 inch, full-frame SLR 36 × 24mm. It is not difficult to use CMOS. Low Light shooting usually outperforms CCD in CMOS, while back-mounted CMOS is superior to the front-mounted CMOS. However, CMOS can be divided into high-end and defensive cameras and mobile phones. However, high-end SLR also uses CMOS.
2. Focal range: at present, the minimum width of the wide-angle end can reach 24mm, and the smaller the shooting range is, the wider the range is. For the long focal end, the optical zoom factor is used. × wide-angle focal length = focal length of the long focal end, A larger value can bring the future closer. At present, the maximum optical zoom factor of a consumer-Level DC can be up to 30 times. Digital zoom is a floating cloud.
3. The maximum aperture. The larger the aperture, the better the low light shooting effect, and the lower the background blur. Currently, the maximum aperture is 1.8. The smaller the background is, the larger the aperture is.
4. Parameters of pixels and image size. It is worth noting that many cameras currently only look at pixels. The higher the pixel, the clearer the image to be taken. In fact, pixels have nothing to do with the image quality. They are just parameters of the image size, high-pixel images are large. If you want to enlarge the advertising images and posters, you should select high-pixel images. Otherwise, you do not need to pursue pixels. Large pixels occupy a large storage space, for general purposes, 5-6 million pixels are enough. The pixels are too high and have no practical significance. Instead, they occupy more storage space. In fact, if the card machine with 1200 pixels is set to 6 million pixels, the photos taken are better than those with 12 million pixels (the pictures are obviously enlarged to 100% ).
5. Optical anti-Jitters can offset some of the jitters and increase the output rate. Digital anti-shake is also a cloud.
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