RE: [amibroker] Re: Dual-core vs. quad-core, AmiBroker Email List Archive

Some motherboard makers provide utilities to monitor temperatures in real time. i.e. ASUS PCprobe. Check your manufacturer’s web site.

OC sounds enticing, but be careful.

After first time your system hangs or corrupts your data because of overclocking you’ll wish you were not as aggressive. It’s might be fun for a gaming system.

All chips on your computer slow down the hotter they get. They get hotter the faster you clock them. Not to mention their lifetime decreases exponentially with temperatures.

Joseph Biran
____________________________________________

From: amibroker@xxxxxxxxxxxxxxx [mailto:amibroker@xxxxxxxxxxxxxxx] On Behalf Of dingo
Sent: Tuesday, May 27, 2008 8:21 AM
To: amibroker@xxxxxxxxxxxxxxx
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.

Paul mentioned Coretemp and although I haven't used it myself it looks like it would do the trick: http://www.alcpu.com/CoreTemp/

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?

From: amibroker@xxxxxxxxxxxxxxx [mailto:amibroker@xxxxxxxxxxxxxxx] On Behalf Of Steve Dugas
Sent: Tuesday, May 27, 2008 11:11 AM
To: amibroker@xxxxxxxxxxxxxxx
Subject: Re: [amibroker] Re: Dual-core vs. quad-core

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 -----

From: Paul Ho

To: amibroker@xxxxxxxxxxxxxxx

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.

From: amibroker@xxxxxxxxxxxxxxx [mailto:amibroker@xxxxxxxxxxxxxxx] On Behalf Of Steve Dugas
Sent: Monday, 26 May 2008 5:47 AM
To: amibroker@xxxxxxxxxxxxxxx
Subject: Re: [amibroker] Re: Dual-core vs. quad-core

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

http://www.ocforums.com/showthread.php?t=516399

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 -----

From: Paul Ho

To: amibroker@xxxxxxxxxxxxxxx

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

From: amibroker@xxxxxxxxxxxxxxx [mailto:amibroker@xxxxxxxxxxxxxxx] On Behalf Of Tomasz Janeczko
Sent: Wednesday, 14 May 2008 5:25 AM
To: amibroker@xxxxxxxxxxxxxxx
Subject: Re: [amibroker] Re: Dual-core vs. quad-core

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@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx, "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@xxx>
>> To: <amibroker@xxxxxxxxxxxxxxx>
>> 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@xxxxxxxxxxxxxxx, "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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