Messages in this thread | | | Date | Wed, 29 Jul 1998 21:16:31 +0200 (CEST) | From | MOLNAR Ingo <> | Subject | Re: 2.1.111: IDE DMA disabled...BLAH...BLAH... |
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On Wed, 29 Jul 1998, Alan Cox wrote:
> Two people has 2.0 DMA problems, many people have 2.1 DMA problems. > > Many people who have SCSI have 2.1 problems but do not have 2.0 problems.
not necessarily. Eg., i have another (old) SMP box, which is heavily overclocked. Back when 2.1 got better and better, errors started popping up. Mysterious file corruptions (which went away after reboot), stuff like that, typical RAM corruption problems. Didnt happen with 2.0, happens with 2.1, still 2.1's only 'fault' is that it's much more effective. So many things have been reimplemented to be as effective as it can go. The last thing that made this particular box fail finally was the %esp 'current' improvement on SMP, which removed that crazy 30 cycles delay caused by reading the CPU ID from the local APIC. Another thing when i had to make BIOS timings somewhat more conservative and add yet another fan was when the dentry cache started being so fast around 2.1.50.
> BTW: Have you checked Ingo's bug report on a possible race introduced in > the IDE driver in 2.1 ???
i do not see any corruption, 'only' lockups, so my problem seems to be different. Also (as i've said in my report), this particular sti() has been in 2.0 as well. So it's just a demonstration, maybe a small clue, maybe maybe a solution.
-- mingo
ps. if it wasnt for this flamewar i wouldnt have gone back and wouldnt have produced this smallish patch, so the 2.1.111 'sledgehammer' change did indeed have some use ;)
ps2. <flame> in 2.0, there was one particular very subtle and hard to reproduce IDE DMA Triton bug observed by a friend of mine. The only developer who cared about this bug was Gadi Oxman (and Linus too). finally, after ~2 months of debugging, it turned out to be a chipset bug, fixed by a flash BIOS update. </flame>
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