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~misfit~
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 Posted: Fri Nov 16, 2007 8:46 pm Post subject: Re: The annoying way that BOINC "throttles".. |
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~misfit~ wrote:
[quote]Patrick Vervoorn wrote:
According to Intel, the ICH9R supports NCQ:
http://www.intel.com/design/chipsets/matrixstorage_sb.htm
You have these 'Matrix Storage' drivers installed?
No, nor can I find any that will install. I>ve downloaded two
different versions so far, both of which tell me my system doesn>t
meet the requirements. One, I double-checked, was definitly for the
ICH9R southbridge. I>ll have to spend more time looking. I see that
for NCQ I have to select AHCI in the BIOS but whenever I do so, when
it comes time to boot from HDD I get a flash of a blue screen, then
back to the start of boot up. I hope I can find drivers that will
install, and fix this, as part of the reason I spent an extra $100
(NZ) on this board and another $120 on the RAM was to have NCQ. I>ve
had the SATA II drives for a while now, bought with this upgrade in
mind.
I have a horrible feeling that I needed to install the RAID drivers
via flopy disk during Windows install now. That will annoy the crap
out of me if that>s the case. I didn>t install them as I have no
intention of running RAID. I really don>t want to re-install XP, I>m
95% of the way to having it how I like it. <fingers crossed
I>ll have to put this issue aside for now, I>ve been busy and it
looks like, tomorrow, I>m doing a new build for my friend. A
Q6600/8800GTX build, we>re getting the mobo tomorrow. Actually, I
should resolve it before I install his, he>s talking of getting a
P35/ICH9R chipset as well because mine>s going so well.
I>ll get back to you on this one.
[/quote]
Woot!!!
I found this page:
http://forums.hexus.net/hexus-hardware/112584-how-enable-ahci-raid-mode-without-reinstalling-windows-p35-ich9-ich9r.html
follwed the instructions and now have NCQ running on my Seagates. :-)
Thanks for prompting me Patrick.
--
TTFN,
Shaun. |
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Jan Knutar
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| Posted: Mon Nov 19, 2007 3:06 pm Post subject: Re: The annoying way that BOINC "throttles".. |
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~misfit~ wrote:
[quote]SETI BOINC seems to throttle on time. For instance, I>ve got my
preferences set to 75% of both CPU cores. It seems that it works on
quarter-second (or similar) chunks of time, 75% being 100% load for 3/4 of
a second, then 0% load for the other 1/4, resulting in 75% average over
the whole second.
[/quote]
There>s actually no other way to make a CPU hog consume X% of CPU other than
to sleep for a certain amount of time and then work again for a certain
amount of time. Having 1s switching time sounds a bit coarse to me though,
especially since it leaves enough time for the power saving features of the
CPU to try adjust.
[quote]thermal cycling isn>t doing my CPU any favours either. Why can>t these
code-monkeys write code that simply uses 75% of the CPU constantly and
smoothly rather than just switching between 100% and 0% load?
[/quote]
Everything that runs on the CPU essentially runs at 100% when it runs. A
word processor will occupy the cpu 100% for blinking the cursor. It>s just
that the amount of time it spends on the CPU to turn the cursor off or on
is so small, so that in order for any measurement program to see it as 100%
it would have to have an update rate of a few hundred thousand times per
second...
A media player playing your favourite mp3 goes to sleep and asks the OS to
wake it up when there>s room in the sound buffer again. The OS gets
notified through an interrupt by the sound chip when it has played a buffer
fragment. The OS wakes up the media player, which will consume 100% CPU
until it has decoded more sound and filled up the sound buffer again. This
probably takes less than a millisecond though. It might also not have had
enough of the mp3 in memory, in which case it will have asked the OS to
give it more data from the harddrive. The player is forced to sleep again,
until the IDE/Sata/USB/etc controller fires an interrupt telling the OS
that the data it requested is now available, the OS wakes up the player
again and feeds it the requested data, and the player consumes 100% CPU
until it does something again which makes it sleep. CPU usage is simply an
average of how much time is spent sleeping and how much time is spent
running.
You might ask why the programmers didn>t choose to switch between working
and not working more frequently? There>s a compromise, the quarter second
boinc isn>t doing anything, the CPU can spend in a reduced power state. If
boinc was switching 100 times per second, which would probably be fast
enough to make all sorts of measurement and monitoring programs show a
"constant" 75%, then CPU would use more power since it would only have
about 25ms at a time to spend in a lower power state. Transitioning between
the different power states takes time and power too, so the power saved
would be less.
If you want the cycle to be much shorter than 100ms you>d have to request
the OS to use a faster timer interrupt, which also increases power
consumption.
I guess it>s up for debate whether the slower switching causes more thermal
stress on the computer compared to faster switching... The best solution,
as was suggested later in this thread, is probably to let it run 100%
daytime and switch it off for the night, if the cooling of the computer at
all can handle full load.. :) |
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~misfit~
Guest
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| Posted: Tue Nov 20, 2007 8:11 am Post subject: Re: The annoying way that BOINC "throttles".. |
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Somewhere on teh interweb Jan Knutar typed:
[quote]~misfit~ wrote:
SETI BOINC seems to throttle on time. For instance, I>ve got my
preferences set to 75% of both CPU cores. It seems that it works on
quarter-second (or similar) chunks of time, 75% being 100% load for
3/4 of a second, then 0% load for the other 1/4, resulting in 75%
average over the whole second.
There>s actually no other way to make a CPU hog consume X% of CPU
other than to sleep for a certain amount of time and then work again
for a certain amount of time. Having 1s switching time sounds a bit
coarse to me though, especially since it leaves enough time for the
power saving features of the CPU to try adjust.
[/quote]
That was happening with my machine. Using RightMark CPU Clock Utility in
monitor mode only, when I had SETI-BOINC using less than 100% of CPU the I
could see that the CPU was dropping from 11x multiplier to 6x every second
or less. Through experience I>ve come to appreciate that things break the
most when either they>re switched on and off a lot of they>re
thermal-cycled. As much as I like to support SETI I wasn>t about to do it if
it was going to shorted the life of my hardware. I>m on an extremely limited
budget and always try to but with longevity in mind. It>d be a shame to
off-set that by risking stress-related early failure.
[quote]thermal cycling isn>t doing my CPU any favours either. Why can>t
these code-monkeys write code that simply uses 75% of the CPU
constantly and smoothly rather than just switching between 100% and
0% load?
Everything that runs on the CPU essentially runs at 100% when it
runs. A word processor will occupy the cpu 100% for blinking the
cursor. It>s just that the amount of time it spends on the CPU to
turn the cursor off or on is so small, so that in order for any
measurement program to see it as 100% it would have to have an update
rate of a few hundred thousand times per second...
A media player playing your favourite mp3 goes to sleep and asks the
OS to wake it up when there>s room in the sound buffer again. The OS
gets notified through an interrupt by the sound chip when it has
played a buffer fragment. The OS wakes up the media player, which
will consume 100% CPU until it has decoded more sound and filled up
the sound buffer again. This probably takes less than a millisecond
though. It might also not have had enough of the mp3 in memory, in
which case it will have asked the OS to give it more data from the
harddrive. The player is forced to sleep again, until the
IDE/Sata/USB/etc controller fires an interrupt telling the OS that
the data it requested is now available, the OS wakes up the player
again and feeds it the requested data, and the player consumes 100%
CPU until it does something again which makes it sleep. CPU usage is
simply an average of how much time is spent sleeping and how much
time is spent running.
You might ask why the programmers didn>t choose to switch between
working and not working more frequently? There>s a compromise, the
quarter second boinc isn>t doing anything, the CPU can spend in a
reduced power state. If boinc was switching 100 times per second,
which would probably be fast enough to make all sorts of measurement
and monitoring programs show a "constant" 75%, then CPU would use
more power since it would only have about 25ms at a time to spend in
a lower power state. Transitioning between the different power states
takes time and power too, so the power saved would be less.
If you want the cycle to be much shorter than 100ms you>d have to
request the OS to use a faster timer interrupt, which also increases
power consumption.
[/quote]
Thanks for the detailed explaination. This is how I remember this group from
a few years ago. :-)
[quote]I guess it>s up for debate whether the slower switching causes more
thermal stress on the computer compared to faster switching... The
best solution, as was suggested later in this thread, is probably to
let it run 100% daytime and switch it off for the night, if the
cooling of the computer at all can handle full load.. :)
[/quote]
I have since set it to 100% (both cores). The CPU runs at 44°C constantly
(love that) in a 20° room. RAC is starting to climb nicely too.
Thanks,
--
Shaun. |
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