On Tue, 28 Sep 2010, Weigand, Stephen D. wrote:
I am connecting from a PC to a Linux system running CentOS
release 5.5 (Final) and it is extremely slow to render plots
to the X11 device.
The Linux timings are just awful, particularly using
X-Win32. Cairo vs. Xlib doesn't seem to matter much.
I have to think it is display rendering load at the displaying
unit [an X server], or network latencies in getting the detail
from the producer [an X client] to the displaying unit [an X
server]
With centos 5 on a local X display [so the X client, and
the X server do not have to push the content through the X
fowarding and across the network sockets, but rather can go
through the lo interface under Linux]:
f <- function(n){
+ for(i in 1:n) qqnorm(rnorm(100))
+ }
system.time(f(20))
user system elapsed
0.220 0.028 2.417
which is quite sprightly ;)
-------------------
Then when I run it on the same hardware, but through two SSH
hops, to, and back from a remote unit in the local subnet,
things fall apart:
[herr...@centos-5 ~]$ ssh xps400
Last login: Tue Sep 28 11:00:05 2010 from centos-5.first.lan
[herr...@xps400 ~]$ ssh centos-5
herr...@centos-5's password:
Last login: Tue Sep 28 09:13:50 2010
[herr...@centos-5 ~]$ R
...
f <- function(n){
+ for(i in 1:n) qqnorm(rnorm(100))
+ }
system.time(f(20))
user system elapsed
0.352 0.272 29.681
-------------------
I build my own R packaging under CentOS and do not have a
packaging suitable for the architecture of that intermediate
box -- installing R to a Debian testing box, and running the X
forwarding connection only one hop, it is again visually
rebdered MUCH slower. I get:
system.time(f(20))
user system elapsed
0.644 0.212 45.089
yikes ;)
I'll get a packaging built under CentOS 5 on that other
architecture overnight, and supplement this post
-- Russ herrold
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