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Hi D - Thank you! I have looked over the
CoreTemp website now, I will install it and run some tests before I go any
further. I definitely want to know that I am not causing temps to rise to a
level that might damage the CPU. I think I will pass on the overclocking for
now, but FYI I am just using the stock fan that came with the computer...may
have to think about changing it if CoreTemp shows overly high temps. Yes my CPU
is the Intel Q6600, I don't really know any details about the
motherboard, I built the computer online at Dell if that tells you
anything... Thanks again, I can report back with CoreTemp results if
anyone is interested...
Steve
----- Original Message -----
Sent: Tuesday, May 27, 2008 11:21
AM
Subject: RE: [amibroker] Re: Dual-core
vs. quad-core
As long as the temp stays down you'll be ok.
Several years ago I had a water cooled dual Xenon rig and had some runs that
took several days - never missed a beat.
Are you using the cpu fan that came with the chip or an
after market one? If you do overclock then you'll definitely need to get
a good after market fan - check www.maximumcpu.com for reviews. I'd
do it anyway just as insurance - the prices are very reasonable unless
you get exotic which shouldn't be necessary.
I looked back in the thread but didn't see where you said
what mother board you're using... And you did mention the 6600 - is that your
cpu?
d
Hi Paul - Something occurred to me today and I
was hoping to get your opinion ( as well as D's or anyone else with the
knowledge who would care to comment ). Do you think, even *without*
overclocking, that running these chips flat-out at 100% for hours or days at
a time could possibly cause overheating and subsequent damage/destruction to
the chip? Is there a simple and cheap way to just monitor the temps (
no overclocking involved ) to be sure we do continue running flat-out
if temps are approaching or entering the danger zone? Thanks very
much!
Steve
----- Original Message -----
Sent: Monday, May 26, 2008 7:44
AM
Subject: RE: [amibroker] Re:
Dual-core vs. quad-core
Steve,
My knowledge on OC is quite limited, I have only
OCed 3 pcs in the last 4 to 5 years. Fortunately, they are all still
working, so you can say that my experiences have been favourable. OC
reminds a lot about Car Hot Rodding in my younger days. they are quite
similar, both are attempts to modify a basically mass manufactured product
to performance higher than their specifications. Both are based on
home grown wisdom rather than instituitionalised research. OCing is
basically elevating both the CPU clock speed as well as that of the memory
bus, and my methods, all from what I read on the internet are always based
on first clocking the memory controller hub (MCH), and once that is
done, overclock the CPU by increasing the multiplier, (CPU speed is
always adjusted as a multiplier of bus speed becasue they need to be
synchronised).
The danger related to OC is always that of
overheating, firstly the CPU, and secondary the MCH. So choosing a MB that
has decent cooling features for particularly the MCH is of the most
importance.(CPU are always well looked after by MB manufacturers, and
increasingly MCH is going the same way). In addition, the faster the
memory, the more sucessful the exercise is. So My advice is always getting
the fastest memory you can afford. (this is even more so given what Tomasz
has said recently in his AB performance tests.
Before you overclock, you need to download a few
tools
1. cpuz
2. coretemp
3. memory tesing
You also need to find a set of instructions for
your MB. I found this set of instruction for my MB pretty good http://www.hardforum.com/showthread.php?t=1169366 In
this instruction, you will find where to download the tools I mentioned,
as well as a good methodology to follow. You may be able to find you MB
specific instructions on this site.
Also I found that disabling all devices that I
dont need helps - these include parallel and serial ports,
basically all the things I dont use and I can disable through
the Bios setting.
Testing: I only use AB for stress and performance
testing (I use the recommened software from the site for diagnostic
tests), because that is what I'm ocing for. What I would suggest would be
to use a few of your AFLs, insert in them a few Getperformancecounter
statements (AB function). These should include a relatively
simple AFL, a long and complicated AFL testing lots of symbols
(to test Memory access performance) and one that
is somewhere in between. At the same time - monitor the
temperatures. These are far more meaningful tests than the stress tests
that most OC sites recommend.
I think dingo is
quite an expert in this area. may be he will say a few
words.
Cheers
Paul.
Hi Paul - I found your comment about
overclocking interesting, have googled around a bit but find that most
of the discussion is over my head. For example The Overclockers
Forum
discusses overclocking the Intel Q6600 chip
on my new computer and people are claiming to get as much as 3.8GH out
of this 2.4 GH chip. If you can find the time, would you mind saying a
few words about overclocking, how it is done, and what are the
dangers/limits etc? Do you need special software to monitor the core
temps? Thanks!
Steve
----- Original Message -----
Sent: Wednesday, May 14, 2008
2:12 AM
Subject: RE: [amibroker] Re:
Dual-core vs. quad-core
I havent noticed any slow down when I
run 2 instances of AB optimizing almost on a continuous bases
on my core 2 Duo. I have 4 Mb L2 cache. In fact with
overclocking, I'm able to increase the core speed significantly, and
noticably faster on AB optimization, without increasing the temps
to above 50 deg C
Hello,
I just run the same code on my relatively new
notebook (Core 2 Duo 2GHz (T7250))
and the loop takes less than
2ns per iteration (3x speedup). So it looks like the data sits
entirely inside the cache.
This core 2 has 2MB of cache and
thats 4 times more than on Athlon x2 I got.
> If what you
say is true, and one core alone fills the memory
> bandwidth,
then there should be a net loss of performance while
>
running two copies of ami.
It depends on complexity of the
formula and the amount of data per symbol
you are using. As each
array element has 4 bytes, to fill 4 MB of cache
you would need 1
million array elements or 100 arrays each having 10000
elements
or 10 arrays each having 100K elements. Generally
speaking people testing
on EOD data where 10 years is just 2600
bars should see speed up.
People using very very long intraday
data sets may see degradation, but
rather
unnoticeable.
Best regards,
Tomasz
Janeczko
amibroker.com
----- Original Message -----
From:
"dloyer123" <dloyer123@xxxxxxcom>
To:
<amibroker@xxxxxxxxxps.com>
Sent:
Tuesday, May 13, 2008 8:12 PM
Subject: [amibroker] Re: Dual-core
vs. quad-core
> Nice, tight loop. It is good to see
someone that has made the effort
> to make the most out of
every cycle and the result shows.
>
> My new E8400
(45nm 3GHz, dual core) system should arrive tomorrow.
> The
first thing I will do will be to benchmark it running ami. I run
> portfolio backtests over a few years of 5 minute data over
a thousand
> or so symbols. Plenty of data to overflow the
cache, but still fit
> in memory. No trig.
>
>
I'll post what I find.
>
> If what you say is true, and
one core alone fills the memory
> bandwidth, then there
should be a net loss of performance while
> running two
copies of ami.
>
>
>
> --- In amibroker@xxxxxxxxxps.com,
"Tomasz Janeczko" <groups@xxx>
>
wrote:
>>
>> Hello,
>>
>> FYI:
SINGLE processor core running an AFL formula is able to
>
saturate memory bandwidth
>> in majority of most common
operations/functions
>> if total array sizes used in
given formula exceedes DATA cache size.
>>
>> You
need to understand that AFL runs with native assembly
speed
>> when using array operations.
>> A simple
array multiplication like this
>>
>> X = Close *
H; // array multiplication
>>
>> gets compiled to
just 8 assembly instructions:
>>
>> loop: 8B 54
24 58 mov edx,dword ptr [esp+58h]
>> 00465068 46 inc
> esi ; increase counters
>> 00465069 83 C0 04 add
eax,4
>> 0046506C 3B F7 cmp esi,edi
>> 0046506E D9
44 B2 FC fld dword ptr [edx+esi*4-
> 4] ; get element of close
array
>> 00465072 D8 4C 08 FC fmul dword ptr
[eax+ecx-
> 4] ; multiply by element of high array
>>
00465076 D9 58 FC fstp dword ptr [eax-
> 4] ; store
result
>> 00465079 7C E9 jl
> loop ; continue until
all elements are processed
>>
>> As you can see
there are three 4 byte memory accesses per loop
> iteration
(2 reads each 4 bytes long and 1 write 4 byte long)
>>
>> On my (2 year old) 2GHz Athlon x2 64 single iteration
of this loop
> takes 6 nanoseconds (see benchmark code
below).
>> So, during 6 nanoseconds we have 8 byte reads
and 4 byte store.
> Thats (8/(6e-9)) bytes per second = 1333
MB per second read
>> and 667 MB per second write
simultaneously i.e. 2GB/sec combined !
>>
>> Now
if you look at memory benchmarks:
>> http://community.compuserve.com/n/docs/docDownload.aspx?webtag=ws-
>
pchardware&guid=6827f836-8c33-4063-aaf5-c93605dd1dc6
>>
you will see that 2GB/s is THE LIMIT of system memory speed on
> Athlon x64 (DDR2 dual channel)
>> And that's
considering the fact that Athlon has superior-to-intel
>
on-die integrated memory controller (hypertransfer)
>>
>> // benchmark code - for accurrate results run it on
LARGE arrays -
> intraday database, 1-minute interval, 50K
bars or more)
>> GetPerformanceCounter(1);
>> for(k = 0; k < 1000; k++ ) X = C * H;
>>
"Time per single iteration
[s]="+1e-3*GetPerformanceCounter()/
>
(1000*BarCount);
>>
>> Only really complex
operations that use *lots* of FPU (floating
> point)
cycles
>> such as trigonometric (sin/cos/tan) functions are
slow enough for
> the memory
>> to keep
up.
>>
>> Of course one may say that I am using
"old" processor, and new
> computers have faster RAM and
that's true
>> but processor speeds increase FASTER than
bus speeds and the gap
> between processor and
RAM
>> becomes larger and larger so with newer CPUs the
situation will be
> worse, not better.
>>
>>
>> Best regards,
>> Tomasz
Janeczko
>> amibroker.com
>> ----- Original
Message -----
>> From: "dloyer123"
<dloyer123@x..>
>> To: <amibroker@xxxxxxxxxps.com>
>>
Sent: Tuesday, May 13, 2008 5:02 PM
>> Subject: [amibroker]
Re: Dual-core vs. quad-core
>>
>>
>>
> All of the cores have to share the same front bus and
>
northbridge.
>> > The northbridge connects the cpu to
memory and has limited
> bandwidth.
>> >
>> > If several cores are running memory hungry
applications, the
> front
>> > buss will
saturate.
>> >
>> > The L2 cache helps for
most applications, but not if you are
> burning
>>
> through a few G of quote data. The L2 cache is just
4-8MB.
>> >
>> > The newer multi core
systems have much faster front buses and
> that
>>
> trend is likely to continue.
>> >
>> >
So, it would be nice if AMI could support running multi cores,
> even
>> > if it was just running different
optimization passes on different
>> > cores. That would
saturate the front bus, but take advantage of
> all
>> > of the memory bandwidth you have. It would really
help those
> multi
>> > day walkforward
runs.
>> >
>> >
>> >
>> > --- In amibroker@xxxxxxxxxps.com,
"markhoff" <markhoff@> wrote:
>> >>
>>
>>
>> >> If you have a runtime penalty when
running 2 independent AB jobs
> on
>> >
a
>> >> Core Duo CPU it might be caused by too less
memory (swapping to
>> > disk)
>> >> or
other tasks which are also running (e.g. a web browser,
audio
>> >> streamer or whatever). You can check this
with a process explorer
>> >> which shows each tasks
CPU utilisation. Similar, 4 AB jobs on a
> Core
>>
>> Quad should have nearly no penalty in runtime.
>>
>>
>> >> Tomasz stated that multi-thread
optimization does not scale good
>> > with
>>
>> the CPU number, but it is not clear to me why this is the
case.
> In
>> > my
>> >>
understanding, AA optimization is a sequential process of
>
running
>> > the
>> >> same AFL script
with different parameters. If I have an AFL with
>>
>> significantly long runtime per optimization step (e.g. 1
minute)
> the
>> >> overhead for the
multi-threading should become quite small and
>> >>
independent tasks should scale nearly with the number of CPUs
> (as
>> > long
>> >> as there is
sufficient memory, n threads might need n-times more
>>
>> memory than a single thread). For sure the situation is
> different if
>> >> my single optimization
run takes only a few millisecs or
> seconds,
>>
> then
>> >> the overhead for
multi-thread-managment goes up ...
>> >>
>> >> Maybe Tomasz can give some detailed comments
on that issue?
>> >>
>> >> Best
regards,
>> >> Markus
>> >>
>> >
>> >
>> >
------------------------------------
>> >
>> > Please note that this group is for discussion
between users only.
>> >
>> > To get
support from AmiBroker please send an e-mail directly to
>> > SUPPORT {at} amibroker.com
>> >
>> > For NEW RELEASE ANNOUNCEMENTS and other news
always check DEVLOG:
>> > http://www.amibroker.com/devlog/
>>
>
>> > For other support material please check
also:
>> > http://www.amibroker.com/support.html
>>
> Yahoo! Groups Links
>> >
>> >
>> >
>>
>
>
>
>
------------------------------------
>
>
Please note that this group is for discussion between users
only.
>
> To get support from AmiBroker please send an
e-mail directly to
> SUPPORT {at} amibroker.com
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check
DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check also:
> http://www.amibroker.com/support.html
>
Yahoo! Groups Links
>
>
>
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Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
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For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
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