:::. P4 HTT and DUMP: Corrupted MAC on input.

Mikhail Goriachev mikhailg at webanoide.org
Fri Aug 18 13:06:53 UTC 2006


I've got the following problem. A few servers, periodically dump(8)
through ssh to a central server. That central server comes with a P4 HTT
(single core - no frills) processor. A few weeks ago I decided to
activate hyperthreading and add SMP capabilities to it. Just for the
sake of it.

Before those modifications, all servers were dumping without any
problems for months, literally. However, now I get random disconnects.
It may disconnect after 4%, 95% or not at all. But eventually, some dump
processes get randomly disconnected. This is the sample error I get:

  DUMP: dumping (Pass IV) [regular files]
  DUMP: 4.60% done, finished in 1:44 at Fri Aug 18 08:45:04 2006
Received disconnect from 2: Corrupted MAC on input.
  DUMP: Broken pipe
  DUMP: The ENTIRE dump is aborted.

After several days of googling and pulling my hair out, for some reason
I decided to get rid off HTT and SMP... and to my amusement, everything
is back to normal. I put back SMP+HTT and the disconnects are back
again. So in conclusion, in this case, SMP+HTT causes random problems in

Any thoughts on why this is happening? I really would like to know. What
about real SMP machines, are they affected as well?

Thanks in advance.


PS: All servers are 6.1-RELEASE-p3 without go-fast-pc flags or whatever.

Mikhail Goriachev

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