rosen@cochlea.bu.edu (David B. Rosen) (03/06/90)
I have a question about the DISPLAY. If the display is local, so no
host field need be specified, is it less efficient if the host name or
internet address *is* specified? That is, does this force all i/o
through network protocols or something even though the display is
local? For example, is it *better* to use `:0.0' than `myws:0.0' as
the DISPLAY varible value for the local display on myws?
Another question: what is the difference between using `unix:0.0' and
simply `:0.0'. Is the latter faster?
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David B Rosen, Cognitive & Neural Systems rosen@bucasb.bu.edu
Center for Adaptive Systems rosen%bucasb@{buacca,bu-it}.bu.edu
Boston University {mit-eddie,harvard,uunet}!bu.edu!thalamus!rosenrws@EXPO.LCS.MIT.EDU (Bob Scheifler) (03/06/90)
If the display is local, so no
host field need be specified, is it less efficient if the host name or
internet address *is* specified?
This is likely to be implementatation/release dependent. In R4, ":0" is
supposed to mean the "best" local communication strategy. For most
implementations right now that's chosen to be Unix Domain sockets (UDS); in
some product implementats a shared-memory connection gets chosen. Whether
UDS is really better than "loopback TCP" depends on the OS. It's possible
that we've made the wrong choice on some systems in R4, but not on purpose.
In R4, we shipped the Apollo config file to use UDS; since then we've released
a patch that de-configures UDS because the TCP path is faster.
For example, is it *better* to use `:0.0' than `myws:0.0' as
the DISPLAY varible value for the local display on myws?
In general, I would say yes.
Another question: what is the difference between using `unix:0.0' and
simply `:0.0'. Is the latter faster?
unix:0 has been removed from the documentation in R4, to avoid trademark
problems. It is still supported in the R4 implementation, but should not
be depended on. You should think of "unix:0" as meaning UDS, whereas ":0"
means best local.klee@wsl.dec.com (Ken Lee) (03/07/90)
In article <ROSEN.90Mar5220252@cochlea.bu.edu>, rosen@cochlea.bu.edu (David B. Rosen) writes: > Is it *better* to use `:0.0' than `myws:0.0' as > the DISPLAY varible value for the local display on myws? > > Another question: what is the difference between using `unix:0.0' and > simply `:0.0'. Is the latter faster? These are all Xlib conventions. You should probably check your Xlib to see what it supports. On most machines, host:0 uses a TCP connection, host::0 uses a DECnet connection, unix:0 uses a UNIX domain socket, and :0 uses whatever Xlib thinks is fastest. In the MIT sample Xlib, :0 is probably the same as unix:0. Some vendor Xlib's may use something shared memory for :0 and/or support other protocols. This is all discussed in Section 2.1 of MIT's Xlib manual. Ken Lee DEC Western Software Laboratory, Palo Alto, Calif. Internet: klee@wsl.dec.com uucp: uunet!decwrl!klee