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#1 2010-09-26 17:06:11

dracoroot7
Member
Registered: 2010-06-01
Posts: 12

copying files to usb drive eats huge amount of cpu

pic 1 http://img185.imageshack.us/img185/7131/cpuc.jpg

pic 2 http://img710.imageshack.us/img710/2848/cpu1r.jpg

I have seen discussions about this problem before, but never any real solution.

Any time I copy files to a usb drive with archlinux cpu usage goes extremely high and sometimes
the copying process hangs for a while before continueing.

I have archlinux 64 bit, nvidia 9800, 8 gig ram, amd phenom ll x4 940

on my dell laptop with an intel cpu, copying file to a jump drive (any) takes up 99% cpu


I notice that in the second pic the process that was taking up the cpu did not show in the list, but as
you can see on the desktop widget and in the second pic cpu usage was up.

This has only ever happened to me with archlinux (which I love)

It's not a kde issue because if I use the command line to copy a file the same thing happens, any thoughts on this issue.

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#2 2010-09-26 17:09:44

lilsirecho
Veteran
Registered: 2003-10-24
Posts: 5,000

Re: copying files to usb drive eats huge amount of cpu

Perhaps your cpu cache is too small to accomodate the processes you are using.

EDIT:  There may be a problem in later Kernels with the cpufreq controls.  It seems if the cpu has 100% usage for a certain time period, it resets to lowest cpu freq and cannot be reset.  This slows the progress of the operation in use and may make the cache slower as well.  This fits the situation you describe and has been reported as occuring frequently in Dell laptops.

It seems that this has appeared in recent kernel releases which may be the result of changes in the cpufreq control entries in the kernel.
Some indications show it to be more prevalent in particular mobo systems.

Last edited by lilsirecho (2010-09-26 18:07:17)


Prediction...This year will be a very odd year!
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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#3 2010-09-26 18:29:04

lilsirecho
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Registered: 2003-10-24
Posts: 5,000

Re: copying files to usb drive eats huge amount of cpu

Added some edits to previous post to expand on the idea of cache size.

Thus, the use of CPU initially is with cache until it is fully utilized and if the 100% cpu time limit is exceeded during the cache utilization, the cpufreq can be throttled to slow the function.

This probably introduces an apparent stoppage in the transfer but a resumption after the cpufreq changes are completed....the changes require use of the I/O until ready to proceed.

The performance would be a function of transfer data size versus cache size.  It occurs most often with large transfers (700MB or more) and slows transfers greatly in many cases reported in googling.


Prediction...This year will be a very odd year!
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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#4 2010-09-26 21:50:29

dracoroot7
Member
Registered: 2010-06-01
Posts: 12

Re: copying files to usb drive eats huge amount of cpu

What I find funny is that I can extract an 8 gig file quicker than I can copy a 1 gig to a jump drive some times. I would think the compressed file would use more I/O.
And I notice that the cpu hit is worst with fat32 jump drives. I see no reason for my quad core to jump to 50% usage to copy a file to a jump drive.

Thanks for the feed back

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#5 2010-09-28 17:52:30

lilsirecho
Veteran
Registered: 2003-10-24
Posts: 5,000

Re: copying files to usb drive eats huge amount of cpu

Perhaps the usage info is erroneous since you have quad core system and possibly the calculations in quad core are misleading or the actual application uses only one core in the case of USB transfers(likely).

Many posts on the subject of file transfers...some solved by using previous kernel.  One such post says that Linus is working on the problem (most report high cpu usage).

It would seem x86_64 systems could be more susceptible to cpu problems due to the larger bit size.
Further comments indicate that some Bioses do not respond to latest kernel techniques resulting in even further clouding of the path to a solution.

Many report that these problems are recent.  Some i7 systems are reported to have serious shut down problems.

Multi-core it seems is in birth pangs....infant mortality so to speak.


Prediction...This year will be a very odd year!
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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