Messages in this thread |  | | Date | Thu, 14 Nov 1996 21:34:33 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: Linux & ECC memory |
| |
On Thu, 14 Nov 1996, Kenneth Albanowski wrote:
> > This is what I'm curious about. Does Linux's NMI code attempt to work > around some memory problems, or does it just panic? Also, can the glue > report successful error-correction, as well as failed error-correction? > (Or is it not useful to know if your memory has/had an error that was > correctable?) > There would have to be someplace (not in available RAM) to store statistics about corrections that occur. Old VAXen do that. The memory controller chips have "ports" than can be read by the OS to obtain statistics. VAX/VMS will write an error log message about what was done and what "page" of memory failed or had to be corrected. If the pages were in kernel space, the system crashes after writing a crash-dump file. If the page was not yet written (used), it is mapped out and the system continues. Pages on old VAXen are only 512 bytes. Such systems will run happily with only 2 megabytes of RAM with about 1/2 or it bad as long as the bad RAM wasn't in use by the kernel.
To my knowledge, there are not any "modern" computers that handle memory errors this well. An uncorrected memory error on SGIs, Suns, and even Crays are fatal. However, on both the SGIs and Grays ECC corrects most memory errors so the fact that they occurred at all is not known to anyone. No statistics are kept. I think some of the newer, faster Suns have ECC. If so, they should respond the same way.
Since RAM access happens so quickly, keeping statistics on corrections that have occurred could seriously impact performance. The performance of VAXes was not seriously affected because they were soooooo sloooow to begin with.
Cheers, Dick Johnson -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Richard B. Johnson Project Engineer Analogic Corporation Voice : (508) 977-3000 ext. 3754 Fax : (508) 532-6097 Modem : (508) 977-6870 Ftp : ftp@boneserver.analogic.com Email : rjohnson@analogic.com, johnson@analogic.com Penguin : Linux version 2.1.9 on an i586 machine. Warning : It's hard to remain at the trailing edge of technology. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
|  |