nanogui: Thread: GrCopyArea is blocking on X11

Hi 

I have made a small app that show a graph scrolling verticaly across its
window (a heart monitor demo)

First i made it so that it would redraw the whole graph every time, this
gave some flicker.
So i redesigend it to use GrCopyArea, now I copy the graph inside the
sanme window with an offset, and just dram the new part of the graph.
(Se code snippet below)

The update of the graph is based on a timer event.

My problem is that when using the flickery version where i redraw the
complete graph, everythis is working fine. But when using GrCopyArea
version, the program suffers from considerable delays, but only on X11,
I have the same app running fine on a mips32 target, using framebuffer.

I discovered that when the delay occours i had to make some mouse events
by just moving the mouse arround inside the microwindows window.

I had a suspicion that the eventloop was somehow broken, so i made a new
app. whth only the graph code just running inside a for() loop. no
events checking at all.
On my mips32 target this version runs for a short while, scrolling the
graph at high speed until the for loop ends and exits as suposed to. But
the X11 version still suffers from delays until i move the mouse arround
in the window, this despite that i no not look at events at all.

By use of printf debugging i see that it is the GrCopyArea function that
blocks. but not every time, it can run a few turns in the loop then it
bloks until a move the mouse, maybe becuase of events in the eventque.

void HeartGraph(){
    const unsigned int data[]= {30,30,30,15, 0, 5,15,20,25,30,
				35,40,45,50,35,20,30,40,25,35,
				30,30,30,30,30,30,30,30,30,30,
				30,30,30,30,30,30,30,30,30,30,
				30,30,30,30,30,30,30,30,30,30};

    static int index;
    GrCopyArea(heartgW, heartgGC, 0, 0, OUT_WIN_WIDTH-2, OUT_WIN_HEIGHT,
	       heartgW, 1, 0, 0);

    GrLine(heartgW, heartgGC,
OUT_WIN_WIDTH-4 ,data[index],OUT_WIN_WIDTH-3,data[index+1]);    
    index=(++index)%49;
}


-- 
Med venlig hilsen/mojn/regards
Martin Hansen
Center for Software Innovation
Stenager 2, DK-6400 Sønderborg, Web: www.cfsi.dk

man, 22 05 2006 kl. 19:48 -0600, skrev Greg Haerr:
> Martin -
> 
> This is indeed pretty strange.  Offhand, I looked around and
> didn't see anything that might cause this behaviour.  You might
> browse drivers/scr_x11.c & kbd_x11.c.

I did, but did not see anythig that catchd my eye.

I probed a bit more with printf's

I tested using a clean stub of my original program, the stub is quoted
below.

What i observe is that the GrCopyArea in srvfunc.c does complete. But
the GrCopyArea in client.c does not.
 Wathing the terminals and the "microwindows" window, i see that after a
lot of succesfull calls the server stops, and the therefore the graph
stops. But the client continues a bit more, then it stops too. I traced
the stop trough GrCopyArea calling LOCK(&nxGlobalLock) calling
nxAllocReq (in nxproto.c) calling nxFlushReq(aligned_len,1)

When the blocking happens, nxFlushReq(aligned_len,1) does not return,
before i move the mouse over the "microwindows" window.

Now the time that I can spend on this task has run out, maybe I will be
given more time later on. But for now i just report my results in the
hope that they are usefull.


#define MWINCLUDECOLORS
#include <stdlib.h>
#include <stdio.h>
#include "nano-X.h"

/* main window dimension */
#define OUT_WIN_WIDTH 200
#define OUT_WIN_HEIGHT 50


/* default colors */
#define BGC BLACK     /* Background color */
#define FGC GRAY      /* Forground color */

/* forward declerations */
void HeartGraph();
void HeartGraph_init();

GR_GC_ID heartgGC;
GR_WINDOW_ID heartgW;

int main(int ac,char **av)
{
    int i;

    if (GrOpen() < 0) {
        printf("Can't open graphics\n");
        exit(1);
    }

    /* make heartgraph window */
    heartgGC = GrNewGC();
    GrSetGCBackground(heartgGC, BGC);
    GrSetGCUseBackground(heartgGC, GR_FALSE);
    heartgW= GrNewWindowEx(GR_WM_PROPS_BORDER, "", GR_ROOT_WINDOW_ID,
			   0,0 , OUT_WIN_WIDTH, OUT_WIN_HEIGHT, BGC);
    GrSetWindowBorderColor(heartgW,FGC);
    GrSetWindowBorderSize(heartgW,1);
    GrMapWindow(heartgW);    

    HeartGraph_init();
    for(i=0;i<100000;i++)
	{
	    HeartGraph();
	}
    GrClose();
    return 0;
}


void HeartGraph(){

    const unsigned int data[]= {30,30,30,15, 0, 5,15,20,25,30,
				35,40,45,50,35,20,30,40,25,35,
				30,30,30,30,30,30,30,30,30,30,
				30,30,30,30,30,30,30,30,30,30,
				30,30,30,30,30,30,30,30,30,30};

    static int index=0;

    GrCopyArea(heartgW, heartgGC, 0, 0, OUT_WIN_WIDTH-2, OUT_WIN_HEIGHT,
	       heartgW, 1, 0, MWMODE_COPY);

    GrLine(heartgW, heartgGC,
OUT_WIN_WIDTH-4 ,data[index],OUT_WIN_WIDTH-3,data[index+1]);    
  index=(++index)%49;
}

void HeartGraph_init(){

    GrSetGCForeground(heartgGC, BGC);
    GrFillRect(heartgW, heartgGC, 0, 0, OUT_WIN_WIDTH, OUT_WIN_HEIGHT);
    GrSetGCForeground(heartgGC, WHITE);

    GrLine(heartgW, heartgGC, 0,30,OUT_WIN_WIDTH-4,30);

}

Looking at your code below, your call HeartGraph()
100,000 times, without waiting reading an event or
calling any function that might empty the event queue.
Instead, you send 1000's of requests to the client,
which likely causes some expose events to be generated,
which are never read.  Eventually, the client queue 
fills up and the system hangs.  It shouldn't do this,
but you ought to run your heart graph on a 
timer, rather than a full CPU speed.

Regards,

Greg


: What i observe is that the GrCopyArea in srvfunc.c does complete. But
: the GrCopyArea in client.c does not.
:  Wathing the terminals and the "microwindows" window, i see that after a
: lot of succesfull calls the server stops, and the therefore the graph
: stops. But the client continues a bit more, then it stops too. I traced
: the stop trough GrCopyArea calling LOCK(&nxGlobalLock) calling
: nxAllocReq (in nxproto.c) calling nxFlushReq(aligned_len,1)
: 
: When the blocking happens, nxFlushReq(aligned_len,1) does not return,
: before i move the mouse over the "microwindows" window.
: 
: Now the time that I can spend on this task has run out, maybe I will be
: given more time later on. But for now i just report my results in the
: hope that they are usefull.
: 
: 
: #define MWINCLUDECOLORS
: #include <stdlib.h>
: #include <stdio.h>
: #include "nano-X.h"
: 
: /* main window dimension */
: #define OUT_WIN_WIDTH 200
: #define OUT_WIN_HEIGHT 50
: 
: 
: /* default colors */
: #define BGC BLACK     /* Background color */
: #define FGC GRAY      /* Forground color */
: 
: /* forward declerations */
: void HeartGraph();
: void HeartGraph_init();
: 
: GR_GC_ID heartgGC;
: GR_WINDOW_ID heartgW;
: 
: int main(int ac,char **av)
: {
:     int i;
: 
:     if (GrOpen() < 0) {
:         printf("Can't open graphics\n");
:         exit(1);
:     }
: 
:     /* make heartgraph window */
:     heartgGC = GrNewGC();
:     GrSetGCBackground(heartgGC, BGC);
:     GrSetGCUseBackground(heartgGC, GR_FALSE);
:     heartgW= GrNewWindowEx(GR_WM_PROPS_BORDER, "", GR_ROOT_WINDOW_ID,
:    0,0 , OUT_WIN_WIDTH, OUT_WIN_HEIGHT, BGC);
:     GrSetWindowBorderColor(heartgW,FGC);
:     GrSetWindowBorderSize(heartgW,1);
:     GrMapWindow(heartgW);    
: 
:     HeartGraph_init();
:     for(i=0;i<100000;i++)
: {
:     HeartGraph();
: }
:     GrClose();
:     return 0;
: }
: 
: 
: void HeartGraph(){
: 
:     const unsigned int data[]= {30,30,30,15, 0, 5,15,20,25,30,
: 35,40,45,50,35,20,30,40,25,35,
: 30,30,30,30,30,30,30,30,30,30,
: 30,30,30,30,30,30,30,30,30,30,
: 30,30,30,30,30,30,30,30,30,30};
: 
:     static int index=0;
: 
:     GrCopyArea(heartgW, heartgGC, 0, 0, OUT_WIN_WIDTH-2, OUT_WIN_HEIGHT,
:        heartgW, 1, 0, MWMODE_COPY);
: 
:     GrLine(heartgW, heartgGC,
: OUT_WIN_WIDTH-4 ,data[index],OUT_WIN_WIDTH-3,data[index+1]);    
:   index=(++index)%49;
: }
: 
: void HeartGraph_init(){
: 
:     GrSetGCForeground(heartgGC, BGC);
:     GrFillRect(heartgW, heartgGC, 0, 0, OUT_WIN_WIDTH, OUT_WIN_HEIGHT);
:     GrSetGCForeground(heartgGC, WHITE);
: 
:     GrLine(heartgW, heartgGC, 0,30,OUT_WIN_WIDTH-4,30);
: 
: }
: 
: 
: 
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søn, 28 05 2006 kl. 18:28 -0600, skrev Greg Haerr:
> Looking at your code below, your call HeartGraph()
> 100,000 times, without waiting reading an event or
> calling any function that might empty the event queue.
Yes, i know. I saw the same problems when this was controlled by a
typical event loop trigered by a timer event. I just made this test to
eliminate that it was my event lop that was missing something.
We have en exebition tomorrow so i cannot provide you more info today.

But when I get back to nornal I will try to give you some test results
from a version with a propper event loop.

Note that this is not a problem when using framebuffer on mips target.
Only when using X11.


-- 
Med venlig hilsen/mojn/regards
Martin Hansen
Center for Software Innovation
Stenager 2, DK-6400 Sønderborg, Web: www.cfsi.dk