System performance during periods of high hard disk activity

Hi,
I have gentoo (kernel 2.6.15-r7) on an AMD 64. My desktop becomes very unresponsive and almost unusable during periods of high hard disk activity. For example, while moving large files and ftp download at 2 MBps. I have been using linux for quite sometime and used to start a movie as it is getting downloaded. I cant even imagine running mplayer now. Even the mouse-movements become so patchy that its is almost impossible to use the computer while heavy downloads/ file movements are going on.

Where can the problem be? I've googled but could find a solution to this.

--Weshall

a couple of things come to mind...
for your kernel, what are your timer settings?

Code:

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Processor type and features  --->
Timer frequency (250 HZ)  --->

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and also, what sceduler?

Code:

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Block layer  --->
IO Schedulers  --->
<*> Anticipatory I/O scheduler
<*> Deadline I/O scheduler
<*> CFQ I/O scheduler
Default I/O scheduler (Anticipatory)  --->

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Those settings are from my 2.6.15-gentoo-r7 Configuration

I find sometimes I get some real poor performance (or used to) before I correctly configured my kernel, somewhat like je_fro said above. In particular, I fixed my issues like that by checking the following part of the kernel config (making sure they're built into the kernel):

Code:

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General Setup ----->
        [*] System V IPC
        [*] POSIX Message Queues
        [ ] BSD Process Accounting
        [*] Sysctl support

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Now, I don't really know if this will help with IO on a hard disk, but I found back a while ago when I first started building kernels that I would have similar symptoms. Basically, my machine would slow down to the point of being completely unusable. Not only would X stop responding, but also music couldn't play in the background and things like that. I found making sure these things were set like this really managed to get it working well.

Thanks for the reply. Here's my kernel configuration ..

Code:

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Timer frequency (250 HZ)  --->
 ( ) 100 HZ
 (X) 250 HZ
 ( ) 1000 HZ

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and my IO scheduler options are similar to je_fro's, default I/O scheduler being set to 'Anticipatory'. The 3 three options suggested my DSwain are also built into the kernel. I have this problem in spite of that ...

--
Weshall

weird. you have dma enabled? (hdparm /dev/hda)

i also got that slowness once, but only when i ran out of swap

oh yeah ... DMA it is. DMA is not enabled and I am not able to do so .... I shall recompile the kernel will DMA support when this computer is free and get back to you guys.

Thanks for the help...

you can enable DMA from hdparm, you should also enable 32bit mode, another suggestion would be to make sure that you have 32bit access enabled in the BIOS as well s set your HD to LBA mode...

DMA should be configurable without having to recompile. With Gentoo edit the /etc/conf.d/hdparm to include the drive and run rc-update putting hdparm in the boot. I'm using all_args="-d1"

The kernel will need to be rebuilt to enable DMA on removable drives like CD/DVD drives.

But before adding it, use hdparm to make sure it does work

hdparm -d1 /dev/hda

sometimes it wont work until you enable the support for your hardware in the kernel, it happened to me once. told me "operating not permitted"

Quote:

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Originally Posted by rocketpcguy

sometimes it wont work until you enable the support for your hardware in the kernel, it happened to me once. told me "operating not permitted"

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doh, that's right, I've been adding my custom hardware in the kernel for so long I forgot what the defaults were :p

After the "Operation not permiited" errors, I recompiled my kernel. Built support for my driver (VIA82CXXX) into the kernel. DMA & 32-bit I/O mode was then automatically enabled when I booted into the new kernel.

This did solve the system performance problems. hdparm -tT /dev/hda now gives:

Code:

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# hdparm -tT /dev/hda

/dev/hda:
 Timing cached reads:  2244 MB in  2.00 seconds = 1121.93 MB/sec
 Timing buffered disk reads:  168 MB in  3.02 seconds =  55.55 MB/sec

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Thanks everbody for help ...