Maximum and maximum optimistic pipelining requests

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JBGood

Maximum and maximum optimistic pipelining requests

Post by JBGood » 2013-11-11, 12:31

Hi,

My question concerns two settings which are Firefox native, but reading comments over the Web leads as often to contradictory assertions and advised values.
What are the pros and cons of increasing/decreasing these two Firefox native values, network.http.pipelining.maxrequests and network.http.pipelining.max-optimistic-requests ? They both default to 4.

Pale Moon Commander lists these values and Pale Moon Commander User's Guide comments them as follow :

Pale Moon Commander / Network / Pipelining
Maximum number of requests in the pipeline: The maximum number of
outstanding requests for page elements for each pipelined connection (request
sent without waiting for receipt of the element).
Default=4 - In about:config : network.http.pipelining.maxrequests
Maximum optimistic pipelining requests: The maximum number of requests
that are put in the pipeline which could have been sent over a separate
connection instead.
Default=4 - In about:config : network.http.pipelining.max-optimistic-requests

Since the time I have been wondering about the effectiveness of modifying these values (goes back to Firefox) I thought I'd share this puzzling here.
Thanks for your comments/advice :thumbup:

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Moonchild
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Re: Maximum and maximum optimistic pipelining requests

Post by Moonchild » 2013-11-11, 13:01

JBGood wrote:What are the pros and cons of increasing/decreasing these two Firefox native values, network.http.pipelining.maxrequests and network.http.pipelining.max-optimistic-requests ?
Well, to start off with, in Firefox, these values do nothing, since Firefox has pipelining off by default.
The values of having both at 4 (I'm not sure if FF has had these values as default always or not) were examined by trial and error and found to be the most optimal in combination with the other Pale Moon pipelining settings. Increasing or decreasing either way will decrease efficiency. Too small values and you're not using pipelining very well, and might as well switch it off. Too large values and you would be queueing requests up too much that would otherwise be made "in parallel" with concurrent connections, reducing efficiency as well. Both at 4 is basically "short, controlled bursts", neither saturating the network, nor causing delays.
"Son, in life you do not fight battles because you expect to win, you fight them merely because they need to be fought." -- Snagglepuss
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JBGood

Re: Maximum and maximum optimistic pipelining requests

Post by JBGood » 2013-11-11, 13:43

Thanks, Moonchild. Indeed Firefox has pipelining off by default, I was assuming pipelining set to on of course, but that was so long ago (my user.js has been following many versions !) that I had forgotten that indeed I was the one who had switched pipelining on ...

Anyway, besides the precision of your explanation I understand once again that in computing (but same elsewhere often as with a motor engine) more is not always better and that optimization often turns around the concept of a right balance rather than the top of a skyscraper :)

Okay :)

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