Hello everyone, I'm currently working on somekind of "fork" of a patch I found(it's a groovebox patch coded by Martin Birkmann). It consume quite a lot of CPU, on my current Laptop equiped with an Intel® Core™ i3-6006U CPU, it ran up 50% on the first core. Since i want to be able to run it on a Raspberry Pi 3, running the patch at about 1 ghz on a single core is just not possible. Then I looked up how I could optimizes the use of the cpu, I tried to use some puredata command flag, tried to simplify and hide most of the GUI and even tried to split up the patch with subprocesses with pd~.

First flags, changes of priority, realtime ect... doesn't do anything for the use of CPU. Secondly hiding some GUI maybe help to grab 1% or 2% of CPU. Finaly, I had great hope that pd~ would allow to spread the CPU all across the proccessor allowing me to run it on the RPI 3, but no it's strange the mother patch of the subprocesses is running at 18-20% of CPU use(about 60% on a single core) consuming more than the initial patch that runs at 10-12% of CPU use. And when I'm running the pd subprocesses they also grasp a load of cpu use, They consume about as much as the mother patch, which is quite the opposite of what I wanted...

So is it normal that the use of pd~ just increases the need of CPU time for pd ? Is there another way to split the audio processing in different pd instances s the calculation is shared by different cores ? Is there some things I could improve in the audio processing section that could help lowering the use of CPU ?

Then I have another problem whenever I wanted to activate the dsp when I was on my RPI pure data craches. Is there someone here that knows why ? What command should I use to use the dsp without crash on a rpi ?

If you don't see any solution to my problem then you maybe can help me in an another way? Since my problem is mainly optimisation, if you have some recommandation to gave about some pure data open source groovebox patch that run well on low spec system it would be great.

First subpatch:

report ->

-   41,17%     9,23%  pd       [unknown]           [.] 0000000000000000                                                                                                
   - 37,73% 0                                                                                                                                                          
      - 17,87% __printf_chk                                                                                                                                            
         + 14,75% vfprintf                                                                                                                                             
           0,96% __printf_fp                                                                                                                                           
      - 5,36% 0                                                                                                                                                        
         - 0xda0580                                                                                                                                                    
         - 0                                                                                                                                                           
              0,73% garray_getarray                                                                                                                                    
              0,67% pd_findbyclass                                                                                                                                     
        3,81% __GI_____strtod_l_internal                                                                                                                               
        2,21% strlen                                                                                                                                                   
        1,77% binbuf_text                                                                                                                                              
        0,82% pd_extern_sched                                                                                                                                          
        0,82% atom_getfloat@plt                                                                                                                                        
        0,61% 0xba25daeb2f749a00                                                                                                                                       
        0,53% atom_getfloat                                                                                                                                            
   - 1,89% 0x300a300a300a300a                                                                                                                                          
        0                                                                                                                                                              
   - 0,73% 0x1bfca50                                                                                                                                                   
        0                                                                                                                                                              
        __printf_chk                                                                                                                                                   
-   18,60%     0,00%  pd       [unknown]           [.] 0x0000000001bfca50                                                                                              
     0x1bfca50                                                                                                                                                         
     0                                                                                                                                                                 
   - __printf_chk                                                                                                                                                      
      - 15,19% vfprintf                                                                                                                                                
           8,65% __GI___printf_fp_l                                                                                                                                    
           0,63% __mpn_mul_1                                                                                                                                           
        0,96% __printf_fp                   
-   15,19%     4,18%  pd       libc-2.23.so        [.] vfprintf                                                                                                        
   - 11,01% vfprintf                                                                                                                                                   
        8,65% __GI___printf_fp_l                                                                                                                                       
        0,63% __mpn_mul_1                                                                                                                                              
   - 4,18% 0x1bfca50                                                                                                                                                   
        0                                                                                                                                                              
        __printf_chk                                                                                                                                                   
        vfprintf                                                                                                                                                       
-   11,33%     0,00%  pd       [unknown]           [.] 0x300a300a300a300a                                                                                              
   - 0x300a300a300a300a                                                                                                                                                ◆
        6,71% _IO_getc                                                                                                                                                 
        1,89% 0                                                                                                                                                        
        1,44% pd_extern_sched                                                                                                                                          
      - 0,54% __GI___libc_read                                                                                                                                         
           entry_SYSCALL_64_fastpath                                                                                                                                   
           sys_read                                                                                                                                                    
           vfs_read                                                                                                                                                    
           __vfs_read                                                                                                                                                  
           new_sync_read                                                                                                                                               
-   10,54%    10,54%  pd       libc-2.23.so        [.] malloc_consolidate                                                                                              
     0xf1                                                                                                                                                              
     malloc_consolidate                                                                                                                                                
-   10,54%     0,00%  pd       [unknown]           [.] 0x00000000000000f1                                                                                              
     0xf1                                                                                                                                                              
     malloc_consolidate                                                                                                                                                
-    8,65%     8,65%  pd       libc-2.23.so        [.] __GI___printf_fp_l                                                                                              
     0x1bfca50                                                                                                                                                         
     0                                                                                                                                                                 
     __printf_chk                                                                                                                                                      
     vfprintf                                                                                                                                                          
     __GI___printf_fp_l                                                                                                                                                
-    6,71%     6,71%  pd       libc-2.23.so        [.] _IO_getc                                                                                                        
     0x300a300a300a300a                                                                                                                                                
     _IO_getc                                                                                                                                                          
-    5,24%     5,23%  pd       pd                  [.] plus_perf8                                                                                                      
     plus_perf8                                             

report no children ->

-   41,17%     9,23%  pd       [.] 0000000000000000                                                                                                                    
   - 37,73% 0                                                                                                                                                          
      - 17,87% __printf_chk                                                                                                                                            
         - 14,75% vfprintf                                                                                                                                             
              8,65% __GI___printf_fp_l                                                                                                                                 
              0,63% __mpn_mul_1                                                                                                                                        
           0,96% __printf_fp                                                                                                                                           
      - 5,36% 0                                                                                                                                                        
         - 0xda0580                                                                                                                                                    
         + 0                                                                                                                                                           
        3,81% __GI_____strtod_l_internal                                                                                                                               
        2,21% strlen                                                                                                                                                   
        1,77% binbuf_text                                                                                                                                              
        0,82% pd_extern_sched                                                                                                                                          
        0,82% atom_getfloat@plt                                                                                                                                        
        0,61% 0xba25daeb2f749a00                                                                                                                                       
        0,53% atom_getfloat                                                                                                                                            
   - 1,89% 0x300a300a300a300a                                                                                                                                          
        0                                                                                                                                                              
   - 0,73% 0x1bfca50                                                                                                                                                   
        0                                                                                                                                                              
        __printf_chk                                                                                                                                                   
-   11,33%     0,00%  pd       [.] 0x300a300a300a300a                                                                                                                  
   - 0x300a300a300a300a                                                                                                                                                
        6,71% _IO_getc                                                                                                                                                 
        1,89% 0                                                                                                                                                        
        1,44% pd_extern_sched                                                                                                                                          
      - 0,54% __GI___libc_read                                                                                                                                         
           entry_SYSCALL_64_fastpath                                                                                                                                   
           sys_read                                                                                                                                                    
           vfs_read                                                                                                                                                    
           __vfs_read                                                                                                                                                  ◆
           new_sync_read  
-   10,54%  pd       libc-2.23.so        [.] malloc_consolidate                                                                                                        
     malloc_consolidate                                                                                                                                                
     0xf1                                                                                                                                                              
-    9,23%  pd       [unknown]           [.] 0000000000000000                                                                                                          
   - 0                                                                                                                                                                 
        3,70% 0                                                                                                                                                        
        1,89% 0x300a300a300a300a                                                                                                                                       ◆
-    8,65%  pd       libc-2.23.so        [.] __GI___printf_fp_l                                                                                                        
     __GI___printf_fp_l                                                                                                                                                
     vfprintf                                                                                                                                                          
     __printf_chk                                                                                                                                                      
     0                                                                                                                                                                 
     0x1bfca50                                                                                                                                                         
-    6,71%  pd       libc-2.23.so        [.] _IO_getc                                                                                                                  
     _IO_getc                                                                                                                                                          
     0x300a300a300a300a                                                                                                                                                
-    5,23%  pd       pd                  [.] plus_perf8                                                                                                                
     plus_perf8                                                                                                                                                        
-    4,18%  pd       libc-2.23.so        [.] vfprintf                                                                                                                  
     vfprintf                                                                                                                                                          
     __printf_chk                                                                                                                                                      
     0                                                                                                                                                                 
     0x1bfca50                               

Second subpatch:

report ->

-   10,54%  pd       libc-2.23.so        [.] malloc_consolidate                                                                                                        
     malloc_consolidate                                                                                                                                                
     0xf1                                                                                                                                                              
-    9,23%  pd       [unknown]           [.] 0000000000000000                                                                                                          
   - 0                                                                                                                                                                 
        3,70% 0                                                                                                                                                        
        1,89% 0x300a300a300a300a                                                                                                                                       
-    8,65%  pd       libc-2.23.so        [.] __GI___printf_fp_l                                                                                                        
     __GI___printf_fp_l                                                                                                                                                
     vfprintf                                                                                                                                                          
     __printf_chk                                                                                                                                                      
     0                                                                                                                                                                 
     0x1bfca50                                                                                                                                                         
-    6,71%  pd       libc-2.23.so        [.] _IO_getc                                                                                                                  
     _IO_getc                                                                                                                                                          
     0x300a300a300a300a                                                                                                                                                
-    5,23%  pd       pd                  [.] plus_perf8                                                                                                                
     plus_perf8                                                                                                                                                        
-    4,18%  pd       libc-2.23.so        [.] vfprintf                                                                                                                  
     vfprintf                                                                                                                                                          
     __printf_chk                                                                                                                                                      
     0                                                                                                                                                                 
     0x1bfca50                               

-    9,92%  pd       [unknown]           [.] 0000000000000000                                                                                                          
   - 0                                                                                                                                                                 ◆
      - 0,73% vfprintf                                                                                                                                                 
           __printf_chk                                                                                                                                                
           0                                                                                                                                                           
           0x1257040                                                                                                                                                   
-    9,69%  pd       libc-2.23.so        [.] __GI___printf_fp_l                                                                                                        
     __GI___printf_fp_l                                                                                                                                                
     vfprintf                                                                                                                                                          
     __printf_chk                                                                                                                                                      
     0                                                                                                                                                                 
     0x1257040                                                                                                                                                         
-    7,65%  pd       libc-2.23.so        [.] vfprintf                                                                                                                  
   - vfprintf                                                                                                                                                          
      - 7,55% __printf_chk                                                                                                                                             
           0                                                                                                                                                           
           0x1257040                                                                                                                                                   
-    5,29%  pd       pd                  [.] 0x000000000008748c                                                                                                        
     0x8748c                                                     

Well I do not see what is the main difference with the result I've shown before, maybe now we know that vfprintf function call is linked to printf_chk, that I didn't seen before while profiling. Also we got a malloc call and some dac call, so if you got any clue of what it could meant it would be great. Then I have to agree profiling isn't easy(it's my first time doing it ^^) but trying to fix the problem as such low level coudl be the best way to find a real fix to this bottleneck.

@mnb Hello ! First I thank you to have uploaded your patches, they're great ! Then to answer you, no I'm using the groovebox 2, the one you recommend. So the problem isn't from the filter object. But since you coded this patch you maybe could run it on your config and report here how much CPU power it takes on your side. By doing this we could identify if the problem is coming from the code or my hardware(I remember reading somewhere that embed intel GPU could have crappy result with pd, so with a bit of luck i could find somekind of driver fix to this issue).

@EEight Well, when I'll get something running fine on my laptop I'll port it to the RPI and of course I'll use -nogui, even switch~ if it's possible. But on the two version of my ptach I got either 50% of my first core(whith a 2Ghz CPU) or on the v2 of the patch 4 cores running at peak over 50%. Considering that my Pi is using a Broadcom BCM2837, with 1,2 Ghz on four cores and that the frequency is lock by the system around 900 MGhz if I'm right, it's just impossible to run my patch now on the rpi. I thinked that in theory splitting the audio processing to spread the calculation over the processor I would get 1ghz of calculation devided in four and then I could reach 250-300 MHz on each cores, that could run very smoothly on a rpi. But because there is something bugging somewehre I've just multiply the audio processing ressources by FOUR ! And -no-gui(that I already use on my laptop) or other tip for optimization such as latency doesn't help the CPU on my laptop, so I don't even think of its efficency on a RPI. I also noticed that when I increased the latency of my pure data instances, CPU use goes up ! So it's not something I could use for optimization. And didn't find ways to run pd on alsa on my Pi the only way I could get it to run without crahsing when dsp is on is with jack.

@lysergik As I understand c++ "everything" goes through a *print call....... https://en.cppreference.com/w/c/io/vfprintf
They are the basic i/o for a running program. If you text search Pd there is no executable that is not swimming in them for very obvious reasons.
You should definitely look at the "output snd_pcm_delay failed" error.
There have been posts (Google finds them) in the past suggesting that it is a RPI kernel problem with alsa and was fixed with a kernel update.
It will be causing dropouts and very possibly your dsp crash.
Any audio problem will cause Pd to struggle with control threads as well, as messages are held up, and will likely make greater demand on the cpu.
David.

Hi @whale-av thanks to give your outlook on this. My performance on groovebox 2 is similar to yours, a bit more CPU use but my CPU is a bit slower so nothing strange. My "fork" of this patch runs with similar specs. Then the error message I got is happening both to my rpi and laptop, so it would explain why I got messed up performances with pd~. I'll try to see if upgradung to new kernel in both OS helps or to find other way to get rid of this. If this solve my issue with pd~ it would be nice, I'll give you guys an update as soon as I have looked into that.

@lysergik I ran a few tests, although they are a bit meaningless for your PI as I have an I7 2.3GHz.
And so I deleted a bit of my last post.
I suppose the GUI using 5% of an 8 core processor would translate to 60% or more on your Broadcom chip.
The Pd process at around 3% ..... about 40% maybe.
Simply minimising the GUI window removes nearly all of the GUI cpu usage as @Eeight suggests.
If you can effectively split the audio equally over 2 cores with [pd~] you might be able to get down to 20-25% per core on the RPI.
Is it possible in Linux to force the GUI...... the tcl/tk app..... to run on a set core..... core 1 GUI / core3 Pd / core4 [pd~] for example.
The wish app and Pd communicate through ports anyway, so that will be possible if there is a way to permanently assign the executables to the cores.
David

Running groovebox2 on my T430 Core i5 i get roughly 35 % of CPU consumed.

I profiled and i get following results (at first look normals):

standard.txt
nochildren.txt

Hi guys, so I manage to get rid of the "output snd_pcm_delay failed" error by running pd with Jack. It doesn't do anything for the CPU, still got my four cores running at 50%. I did some profiling on groovebox 2 and my first my frist version of the "fork" I was working on and I notcied that I didn't get any vfprintf calls, so the problem doesn't come from neither martin Birkmann patch or my first tweaks on it, but only from the implementation of pd~. Since the vfprintf isn't due to the alsa error message, it must be something else. It's not the synth of the patch or the mixer and fx that works well somewhere else. Then the only thing that are remains in this audio processing patch is the following : an object that permits me to get all the value that come from my GUI patch via netsend/netreceive and another object which take the value received via netsend to then them with a message to the pd~ object.

My netsend/netreceive object seems to have worked fine until now I didn't notice any CPU issues when using it. The other object maybe the source of the problem, thoough it's strange because the value that I send from the GUI are sent properly to the audio processing patch. So I'don't know what to do. Should I pack an archive of my code and put it here so you could have a better idea of whats going on ?

groovebox2 (the groovebox2b example) has a load of about 23 percent on my 3.2 ghz haswell i5 using integrated gfx. depending on the fx selected. i can load 6 instances of this patch before i get audio-dropouts (at about 95 percent cpu-load)

while there is probably not much that can be done regarding the gui (it is updated at 1/16 step rate), it should be possible to save cpu by replacing the bandlimited oscillators with simpler ones, and using less, or different fx.
(the xy-one uses quite a lot cpu) and maybe using a simpler reverb. and of course using multithreading/pd~
which would require a bit of work though...

@Nicolas-Danet hello, im a mostly non-programmer but I'm trying to teach myself pd and pd optimization currently. Could you please explain what this means and maybe whether this method might be approprachable by a non-programmer to use to track cpu issues/prototype things? I'm very curious/interested based on your answers/this comment, thanks!

IMHO the base of optimization is to find what worths the cost to be optimized. Don't think you know it without measures. Intuitions are often wrong. In the groovebox2 example above with a lot of GUI it appears that it is negligeable in front of the DSP. You can benchmark objects with [cputime] [realtime] reports to evaluate the cost. But it doesn't matter to have a slow module if it is not used a lot. On the other hand, small gain on an object that is highly polled can save much more CPU.

What makes things more complex In Pure Data is that the DSP and the control commands are interleaved and computed in the same thread. That means that each time a process is too long to achieved (e.g. network, I/O file, anything that can wait) the DSP is rendered too late and you have a click. It means that not only the average of CPU cost for each object and/or algorithm matters but also the instantaneous cost. That ruins all what i said in the first paragraph above! That's why tracking each individual small cost can save Xruns, and why optimizing is a top rated topic.

Is profiling something usable by a non-programmer? TBH i think it is not. To understand the measures (and what's going one i.e. the main loop, scheduling, clocks...) you need to look at under the hood. Even for a programmer, it is not easy. You can have wrong results sometimes when the tests are not really representatives (and thus bad assumptions). It requires a bit of experience (trial and error).

Sometimes i forget that not everybody really wants to spend all that time for nothing!

@Nicolas-Danet said:

Sometimes i forget that not everybody really wants to spend all that time for nothing!

You are not alone!