CONFIG_PIN_TLB and telnet problems

[Benjamin Herrenschmidt]

>
>To add to these comments, I can reproduce the problem as well on a
>unix socket shared either between two processes, or read & written
>by a single process.
>
>After doing various tests, the problem appears rarely and randomly
>with half the RAM mapped with fixed TLBs, and very reproduceably
>with all the RAM mapped this way. So it seems that reducing the
>kernel pressure on TLBs, thus allowing userland TLBs to live much
>longer, exhibit the problem.
>
>I tried adding a call to _tlbia (not the instruction but our tlbwe
>based implementation) in set_context to make sure I only ever have
>one userland context loaded in the TLB and this appear to kill the
>problem (I'm currently running 2 offending test programs simultaneously
>on the box and none failed yet after a few Gb transferred).

Hrm... I added isync/sync (actually, the sync is probably too much)
to set_context() in head_4xx.S in order to invalidate the shadow TLBs
and it seems to work ! I'll test a few hours and let you know.

Ben.


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