cookbook_optimizations.txt

Revision 2466, 5.4 kB (checked in by taher, 1 week ago)
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1	== link:index.html[Index] -> link:cookbook.html[Cookbook]
2
3	Cookbook: Optimizing Cherokee
4	-----------------------------
5
6	Cherokee's default parameters are suitable for most cases. However,
7	there are a number of things that can be tweaked in order to improve
8	the behavior of Cherokee under special circumstances.
9
10	[[compiled]]
11	Compiled capabilities
12	~~~~~~~~~~~~~~~~~~~~~
13
14	First of all you should check the capabilities that have been built
15	into your specific Cherokee build. This can be done by:
16
17	----
18	$ cherokee -i
19	Compilation
20	Version: 0.11.0
21
22	[...]
23
24	Support
25	IPv6: yes
26	OpenSSL: no
27	Pthreads: yes
28	Tracing: yes
29	sendfile(): yes
30	syslog(): yes
31	Polling methods: select poll epoll
32	----
33
34	The last section is interesting. If you see that any siginficant
35	capability supported by your platform is missing, you should really
36	build another binary or check if something is wrong with your
37	system. Note that not every single capability is present in every
38	platform. For instance, `epoll` is a polling method specific to Linux
39	platforms, and its abscence from any non-Linux system is perfectly
40	normal. It is inherently more efficient than the other methods
41	available on Linux. For BSD based platforms `kqueue` is also a great
42	improvement over the most standard `poll`. This is the standard POSIX
43	conformant system call, and will only be available on systems that
44	follow the POSIX standard. From the list above, the capabilities that
45	have a dramatic impact in the speed of Cherokee are the polling
46	methods, the existence of sendfile() and the Pthreads support.
47
48
49	[[tweaks]]
50	Tweaks
51	~~~~~~
52
53	There is no general recomendation that is the best for everybody. In
54	general Cherokee's default values try to offer a good compromise
55	between resources and performance, but for specific cases you will be
56	able to tweak somethings that may (or may not) improve the overall
57	performance. Some of the things to keep in mind are mentioned here.
58
59	Encoding::
60	As it is explained in the link:modules_encoders.html[Encoders']
61	documentation, compressing the information to be sent makes a lot of
62	sense for specific file types. It's Not that much processing power is
63	used to compress a text file, for instance, and hardware is cheaper
64	than bandwidth, so you should encode files whenever it makes sense.
65
66	Handler specific::
67	* CGI, SCGI, FastCGI: link:other_goodies.html#x-sendfile[X-Sendfile]
68	support can be enabled or disabled. If you know what this is, you
69	will know how X-Sendfile improves performance by assigning the task
70	of serving files to the web server while leaving the backend
71	application to run free without waiting for the task to end. This
72	gives you extra performance at no cost, but of course your
73	application must specifically make use of this feature.
74	+
75	* Static Content: IO cache is a caching mechanism that dramatically
76	improves performance serving files. The caching algorithm is very
77	efficient and assures that a file will be immediately served while it
78	remains cached. The usage of IO cache is absolutely recommended in
79	all cases except when the contents of the files are changed
80	frequently. Note that the global _IO Cache_ setting from the
81	_Advanced_ section (see bellow) must be enabled for each individual
82	handler's setting to be taken into account.
83
84	General::
85	+
86	* Timeout: The lower your timeout interval is, the faster you will
87	free up resources at the cost of cancelling viable but slow
88	connections.
89	+
90	* Keep alive: This setting dramatically affects the speed at which
91	repeated connections are served to the same client. This is
92	especially noticeable when an asyncrhonous application is used. The
93	trade off is that, since connections are kept open more time, less
94	connections remain available for other clients in any given
95	moment. Cherokee does a pretty good job at reclaiming unused open
96	connections, especially when the number of connections approaches
97	the limit imposed to the system, but any way you should keep in mind
98	this.
99
100	Advanced::
101	+
102	* Threads: The default value is chosen so that it is more than enough
103	to saturate the processors. You will probably not get much out of
104	this setting, since a higher value will not produce better results
105	and a lower one will simply increase the amount of unused processor
106	power.
107	+
108	* File descriptors: By deffinition, the higher this limit is, the
109	less efficient will your system be in relative terms. However, it
110	is understood that if you are tweaking this value is because you
111	need to, that is, you have a very high load site. In these cases
112	increasing the file descriptors' limit makes sense because the
113	higher this limit is, the more connections Cherokee will be able to
114	handle. By default Cherokee does not touch this value and it uses
115	the one specified by your system.
116	+
117	* IO Cache: This setting allows to enable or diasable server-wide
118	the content caching. If disabled, the _IO Cache_ settings of the
119	static content handlers will also be disabled, no matter what
120	behavior is desired in their specific configuration. This global
121	setting is essential if you are trying to debug a cache-related
122	bug in your server's configuration.
123
124	[[trace]]
125	Debug: Disable TRACE
126	~~~~~~~~~~~~~~~~~~~~
127	When compiled with debugging support, Cherokee's performance is
128	heavily penalized. Being able to trace the state of the web server at
129	a very low level is quite useful when you have to fine tune your
130	infrastructure, but once it is done you should disable this feature.
131	A production environment deserves only the finest tuned binaries.

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