[Bug 216759] [kern] Memory speed with small blocks (1K) up to 35 times slower than host system (under QEMU emulation, but not only)

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Tue Feb 28 20:22:30 UTC 2017


--- Comment #12 from andrew at azar-a.net ---
Ok I tried removing the "hypervisor" feature from CPU and it resulted in
1390MB/s on TSC-low by default in the VPS (same as kvm-clock I must notice)...
So seems like FreeBSD does something as not to run slow with "hypervisor" flag
but it is turned off when you disable the flag.
Also networking stopped working without that flag for some reason, routing
stopped working.

So in the end the only fix I see currently is forcing TSC-low manually in
FreeBSD until the code is fixed not to penalize TSC on all new platforms.

Linux is fixed with disabled kvmclock (seems like debian 7 backport from 8 is
not the latest so that might be the trouble).

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