[ydl-gen] Linux yellow dog manual for dummies
Warren Nagourney
warren at phys.washington.edu
Sun Dec 27 05:46:22 JST 2009
That's very interesting, Rob. Were the apps compiled using the same
compilers (with the same degree of optimization) in both cases? Were
the time differences actual CPU time of just elapsed time?
Apple's scheduler isn't very good and - particularly in Leopard - some
of their background operations in support of their gimmicky stuff
(like spotlight, quicklook or "time machine") take up valuable cpu
time. I have occasionally thought that Apple deliberately gave these
miserable programs higher priority so that things would run slowly on
single processor G4 and G5 machines, compared to the multicore x86
offerings. Leopard's time machine (back up utility) is the worst - it
brings single core machines to a virtual halt. None of this has been a
problem in my dual core G5 (but is very noticeable on my Powerbook).
Another difference might be the Mach kernel that OS X uses. This
hasn't been talked about much, but there was a time when an OS with a
monolithic kernel allowed things like context switches to take place
much more quickly. Supposedly, the microkernel has been improved, but
it is not clear how much.
Cheers,
wn
On Dec 26, 2009, at 12:28 PM, Rob Sanders wrote:
> Warren,
> I'd concur. This application was hugely floating point intensive.
> Graphics ops were not an issue for us. The app used only low-level
> X11 calls (no Motif, or Xt calls even), so what graphics there were
> under OSX had to go through Apple's X11 layer before being seen.
> Most of the testing I had done was using the XServe as the compute
> host, with graphics being redirected to a remote terminal. But I
> still consistently saw about a 2x speed improvement when the app ran
> on YLD 4 vice OSX 10.3. <sigh> Many fond memories....
>
> -Rob
>
> On Dec 26, 2009, at 3:00 PM, Warren Nagourney wrote:
>
>> I think one needs to distinguish between the OS and the CPU. My
>> experience with the G5 is that its floating point performance is
>> between 1.5x and 2x as fast as the equivalent x86. Unfortunately,
>> the fixed point advantages are not there. I use LaTeX a lot and
>> heard that the typesetting speed improved on Macs (running OS X)
>> when Apple switched to intel (same TeX source - this might me in
>> part a reflection on the poorer PPC optimizations in gcc). The
>> intel advantage might be 20% in LaTeX typesetting (this is a single
>> data point from a commercial TeX).
>>
>> On the other hand, the performance of the OS is another matter.
>> Every linux I have installed on a Mac (or PS3) was much less
>> responsive than OS X for similar operations. This is a combination
>> of things like application launching speed and particularly
>> graphics operations, which are slow in PPC linux since there are no
>> good PPC drivers for video cards in linux. This is entirely a user
>> interface issue and a PPC linux server might do very well compared
>> to the competition (I have no experience with this). Of course, the
>> speed of apps which don't use graphics should be the same between
>> linux and OS X since they both use the same compilers.
>>
>> Cheers,
>>
>> Warren Nagourney
>>
>> On Dec 26, 2009, at 8:09 AM, Rob Sanders wrote:
>>
>>> I haven't done much with YDL in some time as I've changed jobs,
>>> but I'd just like to chime in that several years ago that the PPC
>>> Linux's ( YDL for Mac, full RedHat/SuSE on some IBM OpenPower720
>>> hardware) was running rings around the equivalent x86 -or- Alpha
>>> based platforms we were doing some work on. Tried to get my
>>> bosses & customers more interested in it and hit the wall of 'but
>>> it isn't x86'. <sigh>. At the time, a direct comparison of the
>>> *same* base code on a Mac XServe G5 running on YDL4 vice OS X 10.3
>>> had the YDL code twice as fast as the OS X code. Lots of double
>>> precision floating point math, and multiple processes (not
>>> threads) communicating via shared memory. We would routinely max
>>> out any box we were running on.
>>>
>>> -Rob
>>>
>>> On Dec 25, 2009, at 2:37 PM, Warren Nagourney wrote:
>>>
>>>> Thanks, Derick.
>>>>
>>>> Although this is a YDL forum, I am afraid to say that there is no
>>>> comparison between any linux on PPC and OS X. The former simply
>>>> doesn't have the software base that I need. I used to think that
>>>> it would be faster than OS X, but after a few installations of
>>>> linux on Apple computers, I discovered that OS X wins hands down
>>>> in the speed area as well. I think that linux is optimized for
>>>> x86 and of course things like flash are only available on x86
>>>> linux (I hate flash, but it unfortunately has become a standard
>>>> for internet video). There are still some PPC optimizations in OS
>>>> X apps and maybe even some Altivec usage (which allows Quicktime
>>>> to smoothly run at 1080p on my PPC machines). The tasks involved
>>>> in writing my book would have been enormously greater if I had
>>>> used linux instead of OS X.
>>>>
>>>> I notice an increasing dominance of ARM in low power portable
>>>> devices. This is unfortunate, since ARM simply doesn't have the
>>>> computational power that PPC has - I am not sure it even has a
>>>> floating point data type. It is too bad that IBM did such a poor
>>>> job of promoting PPC; we will need to reinvent the wheel with ARM
>>>> when we could have had advanced multi-purpose chips with low
>>>> power consumption from the PPC manufacturers (such as PA semi,
>>>> which Apple bought and converted to ARM).
>>>>
>>>> Anyway, the improvement in the performance of Apple products
>>>> since the switch has been less than stellar, much less than
>>>> expected from Moore's law. My 4 year old G5 has a 1.15 GHz memory
>>>> bus and an 16x dual layer superdrive, which is very competitive
>>>> with the best that Apple can come up with now (for reasonable
>>>> prices). It cost much less than a current machine and doesn't
>>>> require a several thousand dollar investment in software, which I
>>>> would need to make if I use one of Apple's intel superboxes.
>>>>
>>>> Cheers,
>>>>
>>>> Warren Nagourney
>>>>
>>>> On Dec 24, 2009, at 2:28 PM, Derick Centeno wrote:
>>>>
>>>>> You may want to know that you may find decent parts for your
>>>>> system
>>>>> from http://macsales.com/
>>>>>
>>>>> I think we may have to really keep our PowerPC running for
>>>>> longer than
>>>>> that although I did hear of someone developing a multicore PowerPC
>>>>> laptop a month or so ago. I've got to search for who this
>>>>> fellow is
>>>>> again as I lost track, but I did hear of a fellow who created a
>>>>> working
>>>>> Cell based laptop which ran the GameOS and had the OtherOS option.
>>>>> Pretty neat!
>>>>>
>>>>> Caveat: If you replace the power supply or other support parts
>>>>> you
>>>>> shouldn't have trouble running YDL from it. Be careful
>>>>> regarding other
>>>>> components however such as DVD drives: if those go it may be
>>>>> wiser to
>>>>> consider an external DVD drive in that situation. I'm unsure if
>>>>> anyone
>>>>> we knew remains at Fixstars from TSS; it may not be so easy to
>>>>> get the
>>>>> kind of support we became accustomed to. In any case, I'd
>>>>> advise you
>>>>> to consider reviewing what notations remain regarding their
>>>>> advisories
>>>>> regarding which hardware works with YDL and which do not. As
>>>>> best I
>>>>> recall, the past emphasis (by TSS) was to support original Apple
>>>>> parts.
>>>>>
>>>>> So the problems to watch for may not be RAM as much as internal
>>>>> associated devices, such as a newer hard drive or modem or
>>>>> something
>>>>> similar. It may be better to just get an HD which resides on a
>>>>> PCI
>>>>> card which your system should recognize with no problem as an
>>>>> external
>>>>> system; I don't think such a drive would be able to be booted from
>>>>> within YDL. It would be interesting to try that out as a concept
>>>>> though.
>>>>>
>>>>> Anyway enjoy and all the best!!
>>>>>
>>>>> On Thu, 24 Dec 2009 13:57:49 -0800
>>>>> Warren Nagourney <warren at phys.washington.edu> wrote:
>>>>>
>>>>>> Thanks, Derick. I still love the PPC architecture and recently
>>>>>> bought an Apple dual core 2.3 GHz G5 for very little money and am
>>>>>> finding it to be absolutely as fast as I could ever hope for. I
>>>>>> will
>>>>>> keep it for the next 3-5 years (assuming I can keep the power
>>>>>> supply
>>>>>> running) and maybe then, the dominance of x86 may have lessened
>>>>>> (it
>>>>>> can't last forever!).
>>>>>>
>>>>>> Merry Christmas and Happy 2010,
>>>>>>
>>>>>> Warren N
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> =========
>>>>>
>>>>> Refranes/Popular sayings:
>>>>> The Taino say:No hay mal que por bien no venga.
>>>>> There is no evil out of which good cannot blossom.
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>>>>
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