[Bloat] SO_SNDBUF and SO_RCVBUF

Steinar H. Gunderson sgunderson at bigfoot.com
Wed Apr 22 15:11:54 PDT 2015


On Wed, Apr 22, 2015 at 02:42:59PM -0700, Eric Dumazet wrote:
> Sorry, I do not understand you.
> 
> The nice thing about TCP_NOTSENT_LOWAT is that you no longer have to
> care about choosing the 'right SO_SNDBUF'
> 
> It is still CC responsibility to choose/set cwnd, but you hadn't set an
> artificial cap on cwnd.
> 
> You control the amount of 'unsent data' per socket.
> 
> If you set a low limit, application might have to issue more send()
> calls and get more EPOLLOUT events.
> 
> This also means that if you get an abort / eof, you no longer have a
> huge unsent queue that TCP API does not allow to cancel.
> 
> https://insouciant.org/tech/prioritization-only-works-when-theres-pending-data-to-prioritize/

So this URL is basically what I said; you need to have data to prioritize
between for this to be useful. If you just want to send a simple file
(and aborts in HTTP/1.1 basically don't really exist), it doesn't really
matter if you have a huge backlog or not.

So I'm sure it's useful for HTTP/2 or SPDY, but that's already pretty
advanced functionality.

/* Steinar */
-- 
Homepage: http://www.sesse.net/


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