The kvm module parameter halt_poll_ns defines the global maximum halt polling interval and can be dynamically changed by writing to the /sys/module/kvm/parameters/halt_poll_ns sysfs file. However in kvm-hv this module parameter value is only ever checked when we grow the current polling interval for the given vcore. This means that if we decrease the halt_poll_ns value below the current polling interval we won't see any effect unless we try to grow the polling interval above the new max at some point or it happens to be shrunk below the halt_poll_ns value. Update the halt polling code so that we always check for a new module param value of halt_poll_ns and set the current halt polling interval to it if it's currently greater than the new max. This means that it's redundant to also perform this check in the grow_halt_poll_ns() function now. Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx> --- arch/powerpc/kvm/book3s_hv.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index daad638..6503a63 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2526,9 +2526,6 @@ static void grow_halt_poll_ns(struct kvmppc_vcore *vc) vc->halt_poll_ns = 10000; else vc->halt_poll_ns *= halt_poll_ns_grow; - - if (vc->halt_poll_ns > halt_poll_ns) - vc->halt_poll_ns = halt_poll_ns; } static void shrink_halt_poll_ns(struct kvmppc_vcore *vc) @@ -2648,6 +2645,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) else if (vc->halt_poll_ns < halt_poll_ns && block_ns < halt_poll_ns) grow_halt_poll_ns(vc); + if (vc->halt_poll_ns > halt_poll_ns) + vc->halt_poll_ns = halt_poll_ns; } else vc->halt_poll_ns = 0; -- 2.5.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
