Am 12.10.2011 22:02, schrieb Alexander Graf:
Actually, I'd much rather prefer to keep the differences between KVM
and non-KVM low here. THP can potentially also work on TCG, so the
alignment isn't completely moot here. Though it's certainly a lot less
useful, as code isn't directly executed from there and we the rest of
the overhead is a lot higher either way (especially the softmmu one).
Either way, why does valgrind break when we enforce big alignment? That really
sounds more like a valgrind bug than anything else. Memalign is there for
exactly that reason, no?
Alex
Actually, there is even a difference between KVM (x86_64) and KVM (non
x86_64)
in the current code: only x86_64 hosts use the 2 MiB alignment.
Valgrind breaks because it has an assertion which limits the alignment.
This limitation was already discussed in 2008 and still exists in latest
Ubuntu and other distributions (and also in latest Valgrind SVN trunk).
Therefore I don't expect that it will be fixed soon.
See these bug reports, for example:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=489297
http://bugs.kde.org/show_bug.cgi?id=203877
Cheers,
Stefan
