PHWinfo - Afficher un message - Re: For performance, one socket or two with dedicated send/receive?

07/03/2006, 20h52

In article <duitka$30bu$1@calcite.rhyolite.com>,
vjs@calcite.rhyolite.com (Vernon Schryver) wrote:

> In article <barmar-23B8CD.19491306032006@comcast.dca.giganews.com>,
> Barry Margolin <barmar@alum.mit.edu> wrote:
>
> >> Well, the application isn't heavy bidirectional, it will be really
> >> heavy in one direction, and light in the other. I want to guarantee
> >> that the light direction doesn't suffer from any starvation if the
> >> other direction is under heavy load.
> >
> >It shouldn't be a problem. The two directions are effectively
> >independent. Implementations don't usually share any per-connection
> >resources between the two directions, so there's nothing to starve
> >(there may be some system-wide resources that are shared, but then the
> >starvation would affect separate connections just as much as a single
> >connection).
>
> Starvation can happen in the application as well as the operating system
> or network machinery. For example, an application I care about involves
> systems doing what might be described as flooding database changes to
> peers and expecting peers to respond with grouped "commits." Things are
> symmetric. Each system would rather not have incoming commits mixed
> with and so delayed by the far larger database changes in a single TCP
> pipe. The commits from a peer are relatively rare, and far quicker and
> easier to handle that database changes. For various reasons incoming
> commits should have higher priority than incoming database change
> requests. My solution is two TCP connections between each pair of
> peers. Each system handles incoming database changes only after it
> has attended to incoming commits.

This sounds like a very different issue -- you're talking about two
connections for the *same* direction, or for different types of
communication (e.g. FTP's Control and Data connections). The OP was
specifically asking about whether to use separate connections for the
opposite directions.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

07/03/2006, 20h52	#7
Barry Margolin Messages: n/a Hébergeur:	Re: For performance, one socket or two with dedicated send/receive? In article <duitka$30bu$1@calcite.rhyolite.com>, vjs@calcite.rhyolite.com (Vernon Schryver) wrote: > In article <barmar-23B8CD.19491306032006@comcast.dca.giganews.com>, > Barry Margolin <barmar@alum.mit.edu> wrote: > > >> Well, the application isn't heavy bidirectional, it will be really > >> heavy in one direction, and light in the other. I want to guarantee > >> that the light direction doesn't suffer from any starvation if the > >> other direction is under heavy load. > > > >It shouldn't be a problem. The two directions are effectively > >independent. Implementations don't usually share any per-connection > >resources between the two directions, so there's nothing to starve > >(there may be some system-wide resources that are shared, but then the > >starvation would affect separate connections just as much as a single > >connection). > > Starvation can happen in the application as well as the operating system > or network machinery. For example, an application I care about involves > systems doing what might be described as flooding database changes to > peers and expecting peers to respond with grouped "commits." Things are > symmetric. Each system would rather not have incoming commits mixed > with and so delayed by the far larger database changes in a single TCP > pipe. The commits from a peer are relatively rare, and far quicker and > easier to handle that database changes. For various reasons incoming > commits should have higher priority than incoming database change > requests. My solution is two TCP connections between each pair of > peers. Each system handles incoming database changes only after it > has attended to incoming commits. This sounds like a very different issue -- you're talking about two connections for the same direction, or for different types of communication (e.g. FTP's Control and Data connections). The OP was specifically asking about whether to use separate connections for the opposite directions. -- Barry Margolin, barmar@alum.mit.edu Arlington, MA * PLEASE post questions in newsgroups, not directly to me * * PLEASE don't copy me on replies, I'll read them in the group *