Mandriva Linux 2007 - DMA Disabled

[Chandler]

I've been using my old Quantex system (Pentium III 650MHz) for CCTV with Mandriva 2007 and ZoneMinder.  Initially it was very crash happy but I rolled back to an older motherboard BIOS, and relaxed all memory timings and it's been stable for just over a year now.

The load averages were very low just monitoring a single camera so I decided to set it up with Samba shares too but everytime I tried to copy files to its shares, the load average went through the roof (as in 3.0+ on a single core CPU!).

I looked in the list of processes and saw that they only added up to around 20%, so 80% of the processors time was being used up by something else.  Then it occurred to me that perhaps DMA had "become disabled" so I set about looking for instructions on how to enable it, and then I discovered that it's disabled by default on some Linux distributions for stability issues with certain chipsets.

After enabling DMA, the system is running far smoother.

[Mark H]

I'm using an AMD Athlon XP 2500 system that I build around 2000, so I think my system is newer, but it is still obsolete and being put to good use.

Mark H; Are computers really obsolete?

[Chandler]

The secondary IDE channel began playing up. If DMA is enabled, the computer randomly freezes or reverts to PIO (which hammers the slow CPU). I stuck in a �£20 Silicon Image SiI3114 SATA card, and all is good again.

Old hardware can sure be cranky, but it's actually more fun and rewarding to work around its idiosyncracies than to throw a heap of money at a new build. And at least I know of its quirks, whereas a new motherboard almost always brings with it new problems.