On 15.08.2012 16:51, Avi Kivity wrote: > On 08/15/2012 03:45 PM, Michael Tokarev wrote: >> >> But apparently, THP does not work still, even with 2Mb >> alignment: when running a guest, AnonHugePages in >> /proc/meminfo stays at 0 - either in kvm mode or in tcg >> mode. Any idea why? What else is needed for THP to work? > > It does for me: > > AnonHugePages: 368640 kB > > Note the patch you reference doesn't impact thp, just kvm's ability to > propagate them to the shadow page table. > >> >> This is quite a frequent question in #kvm IRC channel, >> and I always suggested using -mem-path for this, but >> I'm curios why it doesn't work automatically when it >> probably should? >> > > Please provide extra info, like the setting of > /sys/kernel/mm/transparent_hugepage/enabled.
That was it - sort of. Default value here is enabled=madvise. When setting it to always the effect finally started appearing, so it is actually working. But can't qemu set MADV_HUGEPAGE flag too, so it works automatically? Thanks, /mjt
