AfterShot Pro and Lightroom

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agorabasta
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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Sat Jul 07, 2012 9:33 am

The Lr responsiveness depends more on the memory subsystem, and not on the speed of the CPU neither on the size of memory above 6-8GB. The CPU speed is more important for the final export rendering, but if a fast CPU takes too long in switching threads, cache flushing, etc, the proggie is simply not responsive to the user control - this is exactly what is meant when people are saying the Lr4 is too slow.

With the Intel CPU's it's necessary to have the internal on-CPU video core to be always switched off, then the system must have more than one memory channel and they have to operate in a dual-channel mode at least.

The AMD CPU/APU's are actually much slower at processing, have lower memory bandwidth, higher memory/cache latencies for the smaller data chunks. But they are are much faster switching the threads and doing cache flush/thrash. And their integrated video doesn't slow the CPU functions as much. That's why a slow cheap AMD system may actually feel much more usable for being quite adequately responsive.

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bakubo
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Re: AfterShot Pro and Lightroom

Unread postby bakubo » Sat Jul 07, 2012 2:32 pm

agorabasta wrote:The Lr responsiveness depends more on the memory subsystem, and not on the speed of the CPU neither on the size of memory above 6-8GB. The CPU speed is more important for the final export rendering, but if a fast CPU takes too long in switching threads, cache flushing, etc, the proggie is simply not responsive to the user control - this is exactly what is meant when people are saying the Lr4 is too slow.


I think I recall that earlier you said something about it being Nvidia that is a big problem with LR performance also.

agorabasta wrote:With the Intel CPU's it's necessary to have the internal on-CPU video core to be always switched off, then the system must have more than one memory channel and they have to operate in a dual-channel mode at least.

The AMD CPU/APU's are actually much slower at processing, have lower memory bandwidth, higher memory/cache latencies for the smaller data chunks. But they are are much faster switching the threads and doing cache flush/thrash. And their integrated video doesn't slow the CPU functions as much. That's why a slow cheap AMD system may actually feel much more usable for being quite adequately responsive.


I wonder if Adobe did all their development and testing using AMD cpu computers? It is a bit surprising, if true, that the Intel cpus which are used in Macs and most Windows computers are not the ones Adobe optimized for.

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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Sat Jul 07, 2012 6:21 pm

There appear to be two separate issues with Nvidia. First is their switchable graphics tech called 'Optimus' that causes the system to switch to and fro with the internal graphic core, and that causes horrible stutters quite often if you don't play 3D games (or any other stuff doing intensive GPU calculations, and Lr/ACR are not using GPU specifically, so here come the switchover stutters). The second is that there are far too many people having Nvidia chipsets in their machines complaining at the Adobe forums about bad slowdowns in Lr4.

Adobe definitely was optimising for Intel machines, but there's only that much it can be optimised. That's the hardware memory system that has to optimised by Intel.

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bakubo
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Re: AfterShot Pro and Lightroom

Unread postby bakubo » Sun Jul 08, 2012 3:49 pm

agorabasta wrote:Adobe definitely was optimising for Intel machines, but there's only that much it can be optimised. That's the hardware memory system that has to optimised by Intel.


I still find it surprising that most other programs don't have a performance problem running on rather high-end Intel cpus. Is LR the only program that is doing something where Intel's "switching threads, cache flushing, etc" is such a problem? Multi-threaded software is not exactly rare. I haven't check the LR forum recently, but my recollection is that Intel cpus were not the distinguishing characteristic between those who were having performance problems and those who weren't. The last time I checked it seemed that no one had come up with what the distinguishing computer characteristics were. Has Adobe started telling people to use AMD cpus to get good LR performance?

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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Sun Jul 08, 2012 7:35 pm

bakubo wrote:I still find it surprising that most other programs don't have a performance problem running on rather high-end Intel cpus.
What 'other programs', Henry? AFAIK, there's none comparable...

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Re: AfterShot Pro and Lightroom

Unread postby bakubo » Sun Jul 08, 2012 9:17 pm

agorabasta wrote:
bakubo wrote:I still find it surprising that most other programs don't have a performance problem running on rather high-end Intel cpus.
What 'other programs', Henry? AFAIK, there's none comparable...


Switching threads is not an unusual thing to do in multi-threaded software, quite the opposite.

By the way, where are you finding all this info? Is it on the LR forum or has Adobe published something? I don't keep up to date on all this stuff so I would be interested in reading what the current Adobe analysis is. I would appreciate a link so that I can read what they have to say.

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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Tue Jul 10, 2012 12:28 pm

Henry,

I'm mostly gathering my info myself.
Here are the scarce facts -
1. Adobe to end support for 32-bit OS's citing validation difficulties;
2. Lr4 is still working with old 2GB process memory limit that is a carry-on from 32-bit OS's.

It means that 2GB is actually not enough, so Lr has to rely heavily on the OS/HW ability to cache data in 'free' memory. And it really does so, as the Task Manager in the Win7/Vista shows that the 'cached' physical memory steadily grows as you start and use the Lr4 (on my 16GB machine it grows from a few hundred MB to over 8GB pretty soon).

So having no possibility to stay within 2GB max 'private working set' memory, the process starts to generate first the 'soft page faults' and look into the 'cached' pages, and after that come the 'hard page faults' meaning that the data has to be read from the disk. This is where the latencies start to heavily affect the responsiveness of the system.

The max 'hard page fault' recovery time for a typical modern Intel 'Sandy Bridge' system with Win7 running off an SSD drive is about 0.3-0.5s - that's eternity. And during that time an Intel system really is near-totally unresponsive - you can only move the mouse and observe an errant slide-show of super-slow screen redraws.

A typical AMD system acts very differently as a 'hard page fault' in one process does not stall the system as much, plus the recovery time and CPU stalls are shorter even though the system is much slower overall.

You may try monitoring actual system latencies and stalls with some simple free proggie like this - http://www.resplendence.com/download/LatencyMon.exe. If you need to choose a new system for Lr4, it's best to choose by the lowest latencies as reported there.

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bfitzgerald
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Re: AfterShot Pro and Lightroom

Unread postby bfitzgerald » Tue Jul 10, 2012 9:07 pm

Amazon have a bit of a blowout price on the FX processors so I pulled the trigger on an FX6100 and I'll spank the a$$ off of it with the unlocked multiplier and see how that pans out. I decided against the 8 module FX ones because I feel it's overkill for me and my days of dumping serious cash into processors is over (ie I cry looking back when I paid top dollar for new processors years back, only to watch them become overtaken with cheaper newer ones)
I'd expect something along the line of a 50% uptake in performance over the current processor at stock speeds, but I'll know more obviously when I get it.
Going on the performance of LR4 on other processors and some pretty beefy ones I do not expect it to cure the slowness, because the slow parts (ie opening it and switching between modules) are not hitting the quad core processor to any significant degree (it's not pushing it past 35% doing this) as I've monitored it.

I did do some video conversions the other day for someone using the GPU as well and it ripped nicely through it even with my "not that expensive" quad core AMD CPU.
One can imagine that using a GPU with LR would have a significant improvement in some ways if they coded it to take advantage of that (ie use it to speed up the conversions) it would probably rip through 36mp files like a hot knife through butter. It's really down to adobe though to get the best out of the hardware that is out there. If I can do video work with ease with my current CPU, then a still image is really a drop in the ocean in terms of punishing a processor performance wise.

We have come a long way since the single core models even at the budget end.
AMD have always done better at the budget end in the market and I don't have a problem with that myself. I could have bought an i-3 CPU for the same price as the FX6100, but as I tend to use multi threaded applications much more..there isn't a lot of doubt where you are better off putting your money if you're not spending big. I built quite a few quad core budget AMD pc's for people and a few 6 core ones for video folks..none have been unhappy with those machines for that type of work. Not everyone wants to splash £200+ on the processor.

But even if I look back to my old Athlon 64 X2 4200..that ran LR 1/2 really not that badly at all, sure I was using mostly 6mp or 10mp image files but it wasn't half bad considering the age of the machine. The newer processors are hugely more powerful than that was, so that's why I'm wondering what went wrong down at Adobe HQ.

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Re: AfterShot Pro and Lightroom

Unread postby pakodominguez » Tue Jul 10, 2012 10:20 pm

agorabasta wrote:The sad fact is that virtually no modern machine is really adequately fast for Lr4, so no diff if that is your machine or mine. Leaving the OS imperfections aside, there are two HW aspects that greatly affect the usability - those are the proc speed and the memory speed/latency...

Win 8 will bring us a solution?
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bfitzgerald
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Re: AfterShot Pro and Lightroom

Unread postby bfitzgerald » Wed Jul 11, 2012 2:32 am

Win 8 death watch more like!
It's an entire debate on it's own.

One point to make quite a simple one some of the newer CPU's have additional instructions added which should improve performance in some intensive tasks.
http://software.intel.com/en-us/avx/

We're stuck with SSE2 I believe with Adobe that's a decade behind in instructions

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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Wed Jul 11, 2012 1:49 pm

pakodominguez wrote:Win 8 will bring us a solution?
So far, the 8 appears to be a mere cosmetic/interface upgrade.

There's simply no good PC OS for the Lr tasks. It would be easier to have a dedicated 'OS' for it, i.e. simply load the application with some cut-down driver set directly atop the BIOS, with no other OS at all.

But that's an approach too drastic and not likely to happen. But not totally impossible, if some OS developer is hired to create an embedded OS for Adobe.

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Re: AfterShot Pro and Lightroom

Unread postby bfitzgerald » Wed Jul 11, 2012 2:13 pm

Missing the point entirely here. There is nothing wrong with the Windows OS that is making LR sloppy performance wise.
It's the software that is poor, not the OS. I'm no MS fan but Win 7 is overall a good OS, most folks are happy with it.

Both DxO and Capture One are using GPU acceleration. I was playing with C1 today on trial and it was fast and response even with D800 raw files I downloaded to test it.
Adobe have lots of choices, open CL/direct X for GPU acceleration, they have unused processor extensions that could yield notable performance gains for users even with modest hardware. Blame everyone but Adobe isn't a strategy that has any basis at all.

It took over 10 seconds to switch from library to develop modules with one D800 raw file this morning, that sucks because LR4 is not even remotely optimal. Adobe are behind the times and for a flagship product they will have to do some serious coding work to get this one sorted out.

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Re: AfterShot Pro and Lightroom

Unread postby pakodominguez » Wed Jul 11, 2012 4:16 pm

agorabasta wrote:Henry,

I'm mostly gathering my info myself.
Here are the scarce facts -
1. Adobe to end support for 32-bit OS's citing validation difficulties;
2. Lr4 is still working with old 2GB process memory limit that is a carry-on from 32-bit OS's.

It means that 2GB is actually not enough, so Lr has to rely heavily on the OS/HW ability to cache data in 'free' memory...

note from Tom Hogarty (Lightroom Product Manager)
https://twitter.com/LR_Tom/status/222889239484973056

"LR is not limited to 2GB of mem for 64-bit systems plus, we constantly evaluate interactive performance, not the sys specs."
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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Wed Jul 11, 2012 6:59 pm

pakodominguez wrote:"LR is not limited to 2GB of mem for 64-bit systems plus, we constantly evaluate interactive performance, not the sys specs."
That may be lies, if the 'private working set' is considered, or that may be true if the cached pages are added into consideration. But everybody and their grannies take the former definition; and then even the old 32-bit XP proggies are not limited to that 2GB, if we assume the latter def. :lol:

(a later) P.S. Pako, you may check the actual memory usage of Lr4 for yourself using the simple Task Manager in Windows. It never grows above 2GB, no matter how laggy the proggie comes starving for more memory. You should tell that boy as much, he deserves.
Last edited by agorabasta on Wed Jul 11, 2012 7:32 pm, edited 1 time in total.

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Re: AfterShot Pro and Lightroom

Unread postby agorabasta » Wed Jul 11, 2012 7:15 pm

bfitzgerald wrote:Missing the point entirely here.
Thanks for admitting that, as you really are :wink:

The problem is that no other developing proggie does its stuff with equally high precision as Lr4 does. Hence much greater calculation workload.

And then, the kind of calculations needed there for that kind of precision doesn't allow for any modern kind of SIMD processing as both the data and the functional transforms applied to that are both point-specific. It means they absolutely cannot be parallelised with any modern kind of SIMD processing, and even less so with the GPU co-processing.

So all that shows in abysmally poor sub-pixel accuracy of DxO/C1 and for that matter of any other proggie's output, which means you have to downscale more for screen viewing and/or print smaller with them.
And with the Lr, you may increase the original pixel density by 150% and get there a very real higher absolute physical resolution ('scale' function under 'lens corrections' module).


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