This is a study note to Udemy class
https://www.udemy.com/tcp-http-spdy-deep-dive/
Web loading performance impacts the user
feeling about the website. The research shows 100ms is the ideal time for web
loading time.
By general, we can improve the web loading
time in the below four areas:
Makeup/content:
Make fewer HTTP request
Optiomize css and scripts
Minimize cookies
Browser:
User
progressive enhancement
Load
scripts without blocking
Use
AJAX
Network:
Use
caching and compression
Use
CDN
Reduce
DNS lookups
Avoid
redirctions
Prefect
commonly used resources
Server:
Load
balancing
Backend
server scripts
Optimize
database
Beside the webserver and backend processing
time, the network overload has a great impact on the web loading time.
TCP was designed and devlopped in 1980
under the lower network condition. It was very good to handle the low bandwidth
network. It is stream focusing with the features such as slow start, sliding
window, congestion windows, nagel argithem etc.
RTT is very important for web response
time. It is controlled by the light traveling time between you and the server
plus lots of other factors such as network device hops, bandwidth.
Then how web load time is influenced by the
TCP/HTTP
1.
1 RTT to establish the TCP
2.
1 RTT to send the HTTP request
and get the response time
3.
1 RTT to get the other date
further than the 3 packages
4.
extermly slow down when package
lost, Retransission happens.
What we can do to improve the response time
1.
paralley TCP sessions
2.
reuse TCP sessions (persistent
HTTP connections)
3.
pre-establish TCP sessions
4.
increase initial congestion
window
5.
use CDN to reduce the RTT
6.
TCP fast open (HTTP GET request
with TCP SYN)
Persistent HTTP Sessions
TCP session is not closed after the HTTP
response is sent. The feature is supported by all major web sites and browsers.
It can save TCP session control overload but will have to keep session in web
server side (more threads or worker process). Timeout is set for apache
Initial congestion window: google
experiment shows 10 is the suitable value for current internet congestion
condition. It can send about 15k data to the browser so the content can be
shown if the page is well designed.
HTTP request is sent in SYN package. Only experimental.
Web loading performance impacts the user
feeling about the website. The research shows 100ms is the ideal time for web
loading time.
By general, we can improve the web loading
time in the below four areas:
Makeup/content:
Make fewer HTTP request
Optiomize css and scripts
Minimize cookies
Browser:
User
progressive enhancement
Load
scripts without blocking
Use
AJAX
Network:
Use
caching and compression
Use
CDN
Reduce
DNS lookups
Avoid
redirctions
Prefect
commonly used resources
Server:
Load
balancing
Backend
server scripts
Optimize
database
Beside the webserver and backend processing
time, the network overload has a great impact on the web loading time.
TCP was designed and devlopped in 1980
under the lower network condition. It was very good to handle the low bandwidth
network. It is stream focusing with the features such as slow start, sliding
window, congestion windows, nagel argithem etc.
RTT is very important for web response
time. It is controlled by the light traveling time between you and the server
plus lots of other factors such as network device hops, bandwidth.
Then how web load time is influenced by the
TCP/HTTP
1.
1 RTT to establish the TCP
2.
1 RTT to send the HTTP request
and get the response time
3.
1 RTT to get the other date
further than the 3 packages
4.
extermly slow down when package
lost, Retransission happens.
What we can do to improve the response time
1.
paralley TCP sessions
2.
reuse TCP sessions (persistent
HTTP connections)
3.
pre-establish TCP sessions
4.
increase initial congestion
window
5.
use CDN to reduce the RTT
6.
TCP fast open (HTTP GET request
with TCP SYN)
Persistent HTTP Sessions
TCP session is not closed after the HTTP
response is sent. The feature is supported by all major web sites and browsers.
It can save TCP session control overload but will have to keep session in web
server side (more threads or worker process). Timeout is set for apache
Initial congestion window: google
experiment shows 10 is the suitable value for current internet congestion
condition. It can send about 15k data to the browser so the content can be
shown if the page is well designed.
HTTP request is sent in SYN package. Only experimental.
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