Why does GIMP use xorg so much?

[joneall]

When using the GIMP perspective tool, I see that xorg uses up to 45-50% of the CPU. This is during the time
when you pull the corners of the image around to pick the shape you want. Afterwards, when you click to
do it, then the CPU is used principally by Gimp.

I thought xorg was just for displaying things, that the calculation for the perspective changing would be
attributed to Gimp by the system monitor.

So what is happening?

The result is that the Perspective Tool is unusably slow.

Help, please.

I have an Intel DC 5400 with 4GB RAM, using Kubuntu 10.04, 64-bit.

Edited to shorten lines --GreyGeek

[dibl]

Re: Why does GIMP use xorg so much?

Yes, I just tried it on my new rig, which is an i7-950 overclocked to 4.2GHz, 6GB of RAM, and a big Nvidia
GPU. Even with all that hardware, the visual deformation, on a 2560x1707 photo, is fairly laggy.

Few computing tasks are as CPU-intensive as graphics manipulation - think of CAD workstations and so
forth. This tool is obviously using mathmatical algorithms to translate your inputs to a visual re-display of
the deformed image. That's going to hog your CPU, similar to other large image manipulations, video
encoding, etc. You are right -- Xorg is just the display function, but behind it the CPU is working hard to do
a zillion calculations to determine what Xorg should be showing you. This is not really a "fixable" situation
-- assuming plenty of memory is installed, the CPU clock rate is pretty much going to determine the speed. I
don't know how much gimp (and its tools) are opimized to take advantage of multi-core CPUs and
hyperthreading -- those could help, potentially.

To do the best you can with your existing hardware, about all you could do is install some minimalist
desktop like Xfce, shut down all non-needed packages, and then run gimp that way. KDE 4 is not helping
your CPU handle the gimp workload, in this case .... :P

[joneall]

Re: Why does GIMP use xorg so much?

Thanks for your analysis, Dibl. What slays me tho is that the perspective tool works better with Gimp under
Windows 7 on the same hardware. Nobody is going to claim that Windows is a light-weight. Is KDE 4 actually
heavier than Windows?

I see xfce is in the Kubuntu repos. If I install it, then will I have a chance to choose it at logon time?

If you run lscpu, what do you see for your CPU MHz? I see 1200.000, but the chip is sold as a 2.7GHz cpu.

Could I have a problem here?

Thanks again ... again.

[dibl]

Re: Why does GIMP use xorg so much?

Depending on how Windows is driving your CPU and graphics (i.e. how well and complete the driver
software was written), there could be some differences -- it's a different OS.

Here's the output of /proc/cpuinfo for the first of 4 cores:

don@aptosidbox:~$ cat /proc/cpuinfo
processor    : 0
vendor_id    : GenuineIntel
cpu family   : 6
model      : 26
model name   : Intel(R) Core(TM) i7 CPU     950 @ 3.07GHz
stepping    : 5
cpu MHz     : 4217.632
cache size   : 8192 KB
physical id   : 0
siblings    : 4
core id     : 0
cpu cores    : 4
apicid     : 0
initial apicid : 0
fpu       : yes
fpu_exception  : yes
cpuid level   : 11
wp       : yes
flags      : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx
 fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good xtopology 
nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt 
lahf_lm dts tpr_shadow vnmi flexpriority ept vpid
bogomips    : 8435.26
clflush size  : 64
cache_alignment : 64
address sizes  : 36 bits physical, 48 bits virtual
power management:

As I have seen on other Intel CPUs, the default frequency is part of the model name, but the actual running
frequency is shown two lines down.

If yours is not showing the frequency that you thought it was running, and the BIOS is supporting
overclocking, you might want to take a look at this: http://www.linux-magazine.com/Online/Blogs
/Productivity-Sauce/Power-Management-with-cpufrequtils

[GreyGeek]

Re: Why does GIMP use xorg so much?

My Sony VAIO is a 64bit dual core with CPU speeds of 1.6Ghz each. lscpu give:

$ lscpu
Architecture:     x86_64
CPU op-mode(s):    32-bit, 64-bit
CPU(s):        2
Thread(s) per core:  1
Core(s) per socket:  2
CPU socket(s):     1
NUMA node(s):     1
Vendor ID:       GenuineIntel
CPU family:      6
Model:         23
Stepping:       6
CPU MHz:        2266.000
Virtualization:    VT-x
L1d cache:       32K
L1i cache:       32K
L2 cache:       3072K
$

[joneall]

Re: Why does GIMP use xorg so much?

This is amazing! lscpu says my cpu is running at 1200 MHz and

cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Pentium(R) Dual-Core CPU E5400 @ 2.70GHz
stepping : 10
cpu MHz : 1200.000
cache size : 2048 KB

says 1200 also. Yet the cpu is sold for 2700 MHz! What in the world is going on here? Is each core running half of the 2.7GHz? I do not understand. Any ideas, anyone?

And GreyGeek's result,of 2266MHz for 2 cpus at 1600MHz apiece is quite odd too?

I see in 'man lscpu' that it says

BUGS
The program at the moment does not handle the system installed with different types of physical processors.

What in the world does that mean? GreyGeek, could you look at /proc/cpuinfo? And dibl, could you run lscpu? Thanks.

[joneall]

Re: Why does GIMP use xorg so much?

I have been scrounging around in Google for dual-core clock articles. Altho nobody quite says so, it seems like each core of a dual-core cpu uses slightly less than half the stated frequency of the cpu. So a 2.4GHz machine will have two 1.2GHz cores. This is different from a multi-pro, where each processor has access to all clock ticks. Agreed so far?

So why does GreyGeek see 2266MHz in /proc/cpuinfo for dual cores each at 1.6GHz? 1.6*2 = at least 3.2, not 2.3. And my cpuinfo shows 1.2, the same as for each core, if my interpretation of lscpu is correct, that it gives the max speed of one core.

On dibl's implied suggestion, I installed cpufrequtils. This gives

$ cpufreq-info
cpufrequtils 006: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 160 us.
hardware limits: 1.20 GHz - 1.90 GHz
available frequency steps: 1.90 GHz, 1.20 GHz
available cpufreq governors: conservative, ondemand, userspace, powersave, performance
current policy: frequency should be within 1.20 GHz and 1.90 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
cpufreq stats: 1.90 GHz:1.10%, 1.20 GHz:98.90% (1)
analyzing CPU 1:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 1
CPUs which need to have their frequency coordinated by software: 1
maximum transition latency: 160 us.
hardware limits: 1.20 GHz - 1.90 GHz
available frequency steps: 1.90 GHz, 1.20 GHz
available cpufreq governors: conservative, ondemand, userspace, powersave, performance
current policy: frequency should be within 1.20 GHz and 1.90 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz.
cpufreq stats: 1.90 GHz:1.10%, 1.20 GHz:98.90% (1)

This seems to allow each core to go up to 1.9GHz, tho I am ~90% (whatever that means) at 1.2GHz. I don't see where it says which governor is serving at the moment.

As far as Gimp goes, it seems to use only one core, so it turns at 1.2GHz. Maybe the Windows version uses both, I have no idea how to see this sort of thing in Windows.

If that's the case, I'm better off running Gimp under Windows. How sad...

[dibl]

Re: Why does GIMP use xorg so much?

root@aptosidbox:/home/don# lscpu
Architecture:     x86_64
CPU op-mode(s):    32-bit, 64-bit
CPU(s):        4
Thread(s) per core:  1
Core(s) per socket:  4
CPU socket(s):     1
NUMA node(s):     1
Vendor ID:       GenuineIntel
CPU family:      6
Model:         26
Stepping:       5
CPU MHz:        4217.632
Virtualization:    VT-x
L1d cache:       32K
L1i cache:       32K
L2 cache:       256K
L3 cache:       8192K

For cpufreq settings, "ondemand" is what it usually defaults to. That works well on my Intel X6800 CPU, which is on an Intel mobo. This i7-950, on an Asus P6X58D-E mobo, does not slow down (BIOS overclocking overrides cpufreq settings), so it stays at the high frequency. Although "ondemand" should allow the CPU to speed up to handle gimp work, you might try setting "performance" and see if it makes any difference. Yes, gimp is probably written for single-threaded operation so only one core (at a time) is going to do the work. The only app I've run lately that was obviously coded to use multiple cores is Devede.

[GreyGeek]

Re: Why does GIMP use xorg so much?

The reason why GreyGeek's says "2266" is because GreyGeek's memory isn't what it used to be.
He "thought" his CPUs were 1.6GHz, but where he recalled that from he does not know. A "cat /proc/cpuinfo" shows:

$ cat /proc/cpuinfo 
processor    : 0
vendor_id    : GenuineIntel
cpu family   : 6
model      : 23
model name   : Intel(R) Core(TM)2 Duo CPU   P8400 @ 2.26GHz
stepping    : 6
cpu MHz     : 800.000
cache size   : 3072 KB
physical id   : 0
siblings    : 2
core id     : 0
cpu cores    : 2
apicid     : 0
initial apicid : 0
fpu       : yes
fpu_exception  : yes
cpuid level   : 10
wp       : yes
flags      : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx
 fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good aperfmperf pni dtes64 
monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm tpr_shadow vnmi flexpriority
bogomips    : 4517.82
clflush size  : 64
cache_alignment : 64
address sizes  : 36 bits physical, 48 bits virtual
power management:

processor    : 1
vendor_id    : GenuineIntel
cpu family   : 6
model      : 23
model name   : Intel(R) Core(TM)2 Duo CPU   P8400 @ 2.26GHz
stepping    : 6
cpu MHz     : 800.000
cache size   : 3072 KB
physical id   : 0
siblings    : 2
core id     : 1
cpu cores    : 2
apicid     : 1
initial apicid : 1
fpu       : yes
fpu_exception  : yes
cpuid level   : 10
wp       : yes
flags      : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx 
fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good aperfmperf pni dtes64
 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm tpr_shadow vnmi flexpriority
bogomips    : 4518.71
clflush size  : 64
cache_alignment : 64
address sizes  : 36 bits physical, 48 bits virtual
power management:
$

Sorry about that. So much for "off the top of my head"...

[joneall]

Re: Why does GIMP use xorg so much?

I finally contacted a former collegue, who put me onto cpuburn. It can be installed from the Kubuntu repos and will give a cpu a run for its money. The program in my case is burnP6. Running it once made one of my cpus jump to 1.9GHz; twice, both of them.

So I did what I had been putting off, because I was a little afraid of it, and updated the BIOS on my motherboard. Lo, behold, now with burnP6, the CPU runs at 2.7GHz like it's supposed to. And running two burnP6 processes makes both processors run at 2.7HGHz.

The bad news is that Gimp is still slow. Running the perspective tool can push the CPU frequency up to 2.7GHz, but that does not seem to be enough for Gimp. Guess I do need a faster CPU.