Re: ECC support

2015-09-15 Thread Jim Thompson
> On Sep 15, 2015, at 5:10 PM, Don Lewis wrote: > > On 15 Sep, Dieter BSD wrote: >> Many of AMD's CPU/APU parts support ECC memory. Not just the top of the >> line parts, but also many of the less expensive, less power hungry parts. >> However, many (most?) of the boards

Re: ECC support

2015-09-15 Thread alex.burlyga.ietf alex.burlyga.ietf
On Tue, Sep 15, 2015 at 3:52 PM, Igor Mozolevsky wrote: > On 15 September 2015 at 23:34, Jim Thompson wrote: > > > > >> I think you’ll find that the default for ‘scrub’ is off on most (perhaps >> all) boards. There are reasons, and these relate directly

Re: ECC support

2015-09-15 Thread Igor Mozolevsky
On 15 September 2015 at 22:52, Jim Thompson wrote: Errors are corrected "on-the-fly," corrected data is almost never placed > back in memory. If the same corrupt data is read again, the correction > process is repeated. Replacing the data in memory would require processing >

Re: ECC support

2015-09-15 Thread Igor Mozolevsky
On 15 September 2015 at 23:34, Jim Thompson wrote: > I think you’ll find that the default for ‘scrub’ is off on most (perhaps > all) boards. There are reasons, and these relate directly to > “significantly diminish system performance”, (above), as well as the > greatly

Re: ECC support

2015-09-15 Thread Jim Thompson
> On Sep 15, 2015, at 5:19 PM, Igor Mozolevsky wrote: > > On 15 September 2015 at 22:52, Jim Thompson > wrote: > > > > Errors are corrected "on-the-fly," corrected data is almost never placed back > in memory. If the same

Re: ECC support

2015-09-15 Thread Don Lewis
On 15 Sep, Jim Thompson wrote: > >> On Sep 15, 2015, at 5:10 PM, Don Lewis wrote: >> >> On 15 Sep, Dieter BSD wrote: >>> Many of AMD's CPU/APU parts support ECC memory. Not just the top of the >>> line parts, but also many of the less expensive, less power hungry parts.

Re: ECC support

2015-09-15 Thread Jim Thompson
ECC is implemented by a ‘hashing’ algorithm that works on eight (8) bytes (64 bits) at a time, and places the result into an 8-bit ECC ‘word’. Errors are corrected "on-the-fly," corrected data is almost never placed back in memory. If the same corrupt data is read again, the correction process

Re: ECC support

2015-09-15 Thread Don Lewis
On 15 Sep, Dieter BSD wrote: > Many of AMD's CPU/APU parts support ECC memory. Not just the top of the > line parts, but also many of the less expensive, less power hungry parts. > However, many (most?) of the boards for these chips do not support ECC, > or at least do not admit to it. They

Re: ECC support

2015-09-15 Thread Andriy Gapon
On 15/09/2015 23:53, Dieter BSD wrote: > Assuming that a board does have the necessary connections but > the firmware does not have ECC support, is there some reason that > ECC support could not be added to the OS instead of the firmware? Yes, there is. The memory controller is programmed by the

ECC support

2015-09-15 Thread Dieter BSD
Many of AMD's CPU/APU parts support ECC memory. Not just the top of the line parts, but also many of the less expensive, less power hungry parts. However, many (most?) of the boards for these chips do not support ECC, or at least do not admit to it. They specify "non-ECC memory". Obviously

Re: ECC support

2015-09-15 Thread Xin Li
On 09/15/15 13:53, Dieter BSD wrote: > I've been running machines with ECC for 15-20 years and have never seen > a report of an ECC error from either NetBSD or FreeBSD. I have seen > reports of ECC errors from Digital Unix. And remember getting panics > due to parity errors on machines before