bm@sumikin.co.jp (Bunpei Matoba) (11/07/90)
I'm not familar with both ultrix and DECstation hardware.
However, I'm involved in a project making a real time control system
using a DECstation 3100 and I have to evaluate software performance
prior to designing the whole system.
My interests are;
1. How long does it take to send a message from a process to
another process in the same machine using a socket inter-process
communication mechanism?
Does the message transfer mechanism require delay of micro-second order
or millisecond order?
2. How long does it take to receive a single packet message from
another machine via TCP connection on ethernet?
I measured those items before on Multibus-based computers using
a logic analyzer monitoring internal hardware signals.
For example, in order to measure the delay for a message exchange,
I inserted a simple code for changing voltage of a hardware line
just before a "send" system call and just after a "receive" system
call respectively.
By monitoring the H/L state change of the hardware line
connected to a external logic analyzer I could know the precise
delay time between two system calls.
I'd like to apply the simular method to the case of DECstion3100.
Is there any hardware lines which satisfy the following conditions?
1. The lines are available on a DECstation 3100 machine of standard
hardware configuration.
2. The lines are easily found outside of the machine.
(if it is impossible, inside of the machine OK)
3. We can easily change a voltage of the lines in a test program by calling
c language level functions. And the change takes place just after
calling the function within a period shorter than 100 micro-seconds.
I know this question is too "hard" in this newsgroup.
I would be very happy, however, if anyone could post a reply.
Thank you very much in advance.
bm@sumikin.co.jp
Bunpei Matoba
Computer Engineer
Sumitomo Metal Industries Control &
Engineering Corporation, JAPAN
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CompuServe 72300,3551jg@crl.dec.com (Jim Gettys) (11/07/90)
This is not quite the data you were asking for. In any case, measured using X11perf (i.e. user level code talking to a real X server), a ROUND TRIP (message from x11perf, processing of it in the X server, and a response) is 2 milliseconds on machine using Unix domain IPC, 3 milliseconds using TCP, with Ultrix 4.0 on a DECstation 3100, and across the network with TCP, it is 3.6 milliseconds for the ROUND TRIP. This includes the process scheduling, and everything, for a complete round trip. One could probably do marginally better than this, and whether the measurement methodology is what you'd like is another question as well. - Jim
bm@sumikin.co.jp (Bunpei Matoba) (11/16/90)
Thank you very much for a benchmarking report for inter-process communication performance on a DECstation 3100 by Jim Gettys. > In any case, measured using X11perf (i.e. user level code talking to > a real X server), a ROUND TRIP (message from x11perf, processing of > it in the X server, and a response) is 2 milliseconds > on machine using Unix domain IPC, 3 milliseconds using TCP, with Ultrix 4.0 > on a DECstation 3100, and across the network with TCP, it is 3.6 > milliseconds for the ROUND TRIP. This includes the process scheduling, > and everything, for a complete round trip. I just know that X11perf is a bench marking codes for X-windows and it outputs messages including a line like this; Sync time adjustment is xx.xxxx msecs. I guess that the ROUND TRIP time Jim said is equivalent to the " Sync time adjustment". My understanding of Jim's report is; -----------DECstation 3100 -----( standalone )------------------------- | -------------------- Unix domain IPC(socket) --------------- | | | X-client: X11perf| -------------------------- | X-server: | | | | | 2.0 msec | | | | | | | <------------------------- | | | | -------------------- --------------- | ----------------------------------------------------------------------- --- DECstation 3100 ----- ----DECstation 3100-- | -------------------- | TCP/IP Ethernet | --------------- | | | X-client: X11perf| |------------------------ | | X-server: | | | | | | 3.6 msec | | | | | | | | |<----------------------- | | | | | -------------------- | | --------------- | ------------------------- --------------------- Is it correct? Please let me know, if my understanding is wrong. bm@sumikin.co.jp Bunpei Matoba Sumitomo Metal Industries Control and Engineering Corporation Amagasaki Japan -- $BE*>lJ8J?(J (MATOBA, Bunpei) bm@sumikin.co.jp$B!J=;M'6bB0!K(J $B=;6b@)8f%(%s%8%K%"%j%s%03t<02q(J$B<R(J $B%3%s%T%e!<%?@)8fIt(J phone. NTT (06)418-4715 SUN-NET +671-2602 fax. NTT (06)418-4764 CompuServe 72300,3551