PPC: BookE: Make FIT/WDT timers at best millisecond grained

Enterprise / Virtualization / QEMU - Alexander Graf [suse.de] - 25 November 2013 22:35 UTC

The default granularity for the FIT timer on 440 is on every 0x1000th transition of TB from 0 to 1. Translated that means 48828 times a second.

Since interrupts are quite expensive for 440 and we don't really care about the accuracy of the FIT to that significance, let's force FIT and WDT to at best millisecond granularity.

This basically restores behavior as it was in QEMU 1.6, where timers could only deal with millisecond granularities at all.

This patch greatly improves performance with the 440 target and restores roughly the same performance level that QEMU 1.6 had for me.

84dc96e PPC: BookE: Make FIT/WDT timers at best millisecond grained
hw/ppc/ppc_booke.c | 6 ++++++
1 file changed, 6 insertions(+)

Upstream: git.qemu.org

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