Two questions

On 2015-09-16 16:23, PeterN wrote:

Thanks, sounds like good information. Since I am doing pre-purchase
research, I will not be doing the experiments. I am thinking quad core
with about a 3.5 - 3.8 CPU. I know there are faster, but I am not yet
convinced that the additional price is worth the extra cost.

Typically it's not. If you're trading RAM for CPU always go for more
RAM and less clock. More cores and less clock is good too.

8 GB is not expensive. 16 GB is affordable. (Generally it is cheaper
to buy a desktop computer with 8 GB and then eventually add 16 GB in the
3rd and 4th slots for 24 GB total. Then you're talking - and it leaves
you the option to swap the 8 GB bank for 16 in the future)

Even under high loads a dual core (HT) (most recent i5's for example run
4 threads) computer won't use 99% of all the CPU resources - certainly
not in Photoshop - or when it does it's a fleeting thing.

If you do a lot of video processing, then by all means more cores,
higher clock and more memory is the way to go.

GPU use is also increasing in many photo apps like Photoshop.
For example, Adobe will be adopting OS X "Metal" in upcoming versions of
Photoshop/Lightroom, and so on. Under Windows Adobe GPU use is done by
the less efficient OpenGL in Lightroom and camera raw.

On 2015-09-17 10:01, PAS wrote:
"PeterN" wrote in message
...

Thanks, sounds like good information. Since I am doing pre-purchase
research, I will not be doing the experiments. I am thinking quad core
with about a 3.5 - 3.8 CPU. I know there are faster, but I am not yet
convinced that the additional price is worth the extra cost.

Anytime I've built a new system, I never opted for the fastest
processor, second or third fastest is fast enough. I doubt that there
is any noticeable difference except in benchmark testing. In real world
scenarios, I doubt we would notice and performance difference between
the first, second, and third fastest processors.

If you're talking clock and cores, then there is one real world test
where everything counts: processing video, especially in an efficient
program like Handbrake. It saturates every core and even hyperthread on
intel machines. So a 4 core machine runs full tilt equating about 5.3
cores X nearly 100% processing / core.

I've always used AMD processors. Except for a period of time after the
original AMD Athlon processor was released, Intel has always been the
performance champion. For my use, AMD processors are just fine and are
an excellent value.

Yep. But the advantages of HT on intel cannot be underestimated. A 4
core processor gets over 5.3 cores of performance (in optimal
conditions, of course).

My most recent iMacs have been maxed out. Resale value is astounding
after 5 years - so worth the premium.

In article , Pablo
wrote:


All game consoles had/have sprites. It just means a bitmap in hardware
(simplified). A mouse cursor on a PC is the same thing. But the processor
still has to be aware of it's "events". Otherwise what use is a
mouse/cursor? Even if it's controlled in hardware, the running software
still has to know what's going on. "Hello Proc, Mouse here, I just moved
a bit to the left".

moving the cursor is not an 'event'. no cpu is needed for it to move.

Ok, so when a programme wants to know where the mouse cursor is, how the
hell does it know? What the hell is the point of a mouse if programs don't
even know where the cursor is?

if an app wants to know where the mouse is, then it can query for its
position.

otherwise, there's no need to know.

On 17/09/2015 17:27, PAS wrote:
[]
"Installing Photoshop on a solid-state disk (SSD) allows Photoshop to
launch fast, probably in less than a second. But that speedier startup
is the only time savings you experience. That's the only time when much
data is read from the SSD.
To gain the greatest benefit from an SSD, use it as the scratch disk.
Using it as a scratch disk gives you significant performance
improvements if you have images that don't fit entirely in RAM. For
example, swapping tiles between RAM and an SSD is much faster than
swapping between RAM and a hard disk."


Of course, what does Adobe know about their own application?

... and would not 32 GB RAM be even better?

--
Cheers,
David
Web: http://www.satsignal.eu

On 2015-09-17 11:22, Whisky-dave wrote:
On Thursday, 17 September 2015 16:12:06 UTC+1, Sandman wrote:
In article , Mayayana wrote:

| Not if you only have two cores. I have sixteen cores and
filters obviously runs | on all eight cores: | |
http://jonaseklundh.se/files/photoshop_cpu.jpg |

Very interesting. Your image seems to indicate that it's going
to the other extreme. Rather than splitting the operation across
2 or 3 cores it's using every core, presumably suffering time
slices on one or more of those. It would be interesting to know
how that operation compares to running on something like dual
core. Have you done much testing? Do you find that an operation
will be, say, 10 times faster on the 16 core, or is it just a bit
faster?

More cores doesn't always end up with better performance due to
what is known as the Amdahl's Law that says that a
non-unsignificant part of the CPU tasks are sequential and cannot
be parallelized.


On any given modern computer and OS there are hundreds of threads active
at any time so a 4 core machine has plenty of work waiting for it in the
queues. When each queue is sched to go, there is a thread to take it on
whether wait-available or pre-empted from some other task.

But as a general rule it appears that buying a 'computer' with more
cores will be faster at getting a partucilar job done than one with
lessor cores of about the same speed. Not sure how effciciently OS X
yosemite is on multiple cores compared to W10, W8 or W7.

It's fine. I have 8 threads running at all times (4 core machine).
Depending on the apps or mix, the load tends to be most on the 4 'A'
threads and about half that on the 'B' threads. Some apps (Handbrake)
can saturate the 'A' threads to nearly 100% and the 'B' threads to about
90%. Overall load indicated at nearly 800% means about 530% (5.3)
"real" core loads. (A HT 2nd register set (as I call them 'B' above)
gets you about 30% of a full core _if_ the 'A' thread is at 100%. If
the 'A' thread is not saturated then the 'B' thread can do more work if
there are instructions and data to work on.[1]).

Not sure how Windows does except that under virtualization I assign
Windows 2 cores (it uses 2 'A' threads and 2 'B' threads) and it seems
to use what it needs. OTOH my Windows use is fairly light.

[1] Note that if an 'A' thread shows 100% and the same core's 'B' thread
shows 100%, then one of the two is only really running at about 30% of a
full core capacity - or rather the "200%" is really closer to 130% of a
full core.

In article , David Taylor
wrote:

.. and would not 32 GB RAM be even better?

sure, but the difference between 16 and 32 gig is not that much for
most users. it only matters if 16 gig is somehow limiting.

On 2015-09-17 11:22, Whisky-dave wrote:
On Thursday, 17 September 2015 16:12:06 UTC+1, Sandman wrote:
In article , Mayayana wrote:

| Not if you only have two cores. I have sixteen cores and
filters obviously runs | on all eight cores: | |
http://jonaseklundh.se/files/photoshop_cpu.jpg |

Very interesting. Your image seems to indicate that it's going
to the other extreme. Rather than splitting the operation across
2 or 3 cores it's using every core, presumably suffering time
slices on one or more of those. It would be interesting to know
how that operation compares to running on something like dual
core. Have you done much testing? Do you find that an operation
will be, say, 10 times faster on the 16 core, or is it just a bit
faster?

More cores doesn't always end up with better performance due to
what is known as the Amdahl's Law that says that a
non-unsignificant part of the CPU tasks are sequential and cannot
be parallelized.


But as a general rule it appears that buying a 'computer' with more
cores will be faster at getting a partucilar job done than one with
lessor cores of about the same speed. Not sure how effciciently OS X
yosemite is on multiple cores compared to W10, W8 or W7.

A simpler version of my other reply:

OS X manages processes and process threads. Typically there are over a
hundred threads active for the OS alone (131 kernel threads right now on
my machine) - and any given app / program can fork out as many times as
it wants. So for a multi core machine there is always work to do
somewhere.

OS X slices to 10 ms. Long running threads will be pre-empted. Short
running threads will complete and the next in queue will run if it is
time for it to run.

A lot of idling, of course, in the meantime because threads are waiting
for a scheduled run time unless there's a large load on (like Handbrake).

On 9/17/2015 6:30 AM, David Taylor wrote:
On 16/09/2015 21:23, PeterN wrote:
[]
Thanks, sounds like good information. Since I am doing pre-purchase
research, I will not be doing the experiments. I am thinking quad core
with about a 3.5 - 3.8 CPU. I know there are faster, but I am not yet
convinced that the additional price is worth the extra cost.

The price vs. performance goes up very steeply at the top end of the
performance range. I always try to come down one or two steps as you're
unlikely to notice the performance difference in typical use - unless
you are a games or doing a lot of very heavy video processing. Lower
clock speed may also result in lower temperatures, and hence better
system reliability.


That is my thinking. I do not do computer games, and gave up flight
Simulator after 9/11. Prior to 9/11 I had started to look at multiple
screen cockpits, with motion seats.

--
PeterN

On 2015-09-17 17:48:31 +0000, David Taylor
said:

On 17/09/2015 17:27, PAS wrote:
[]
"Installing Photoshop on a solid-state disk (SSD) allows Photoshop to
launch fast, probably in less than a second. But that speedier startup
is the only time savings you experience. That's the only time when much
data is read from the SSD.
To gain the greatest benefit from an SSD, use it as the scratch disk.
Using it as a scratch disk gives you significant performance
improvements if you have images that don't fit entirely in RAM. For
example, swapping tiles between RAM and an SSD is much faster than
swapping between RAM and a hard disk."


Of course, what does Adobe know about their own application?

.. and would not 32 GB RAM be even better?

Yes, if your work needs it. I make do with 16GB.

--
Regards,

Savageduck

In article 201509171104071059-savageduck1@REMOVESPAMmecom, Savageduck
wrote:

.. and would not 32 GB RAM be even better?

Yes, if your work needs it. I make do with 16GB.

for some purposes, 4 gig is fine.

it depends on what someone is actually doing.

blindly getting 16 gig or 32 gig just because it's the maximum could
easily be a waste of money.