20 lines
997 B
C
20 lines
997 B
C
Without this patch any waits for periods shorter than a single tick return
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immediately leading to a lot of unnecessary spinning. For example, I observe that
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my guest's idle loop does a lot of sleeps with periods slightly shorter than 1 ms
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(1/hz), e.g. 900us. All that waiting turns into pure spinning and VirtualBox eats
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100% of a core.
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The patch improves the situation significantly. Also, it (approximately) follows
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what tvtohz does.
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Submitted by: Andriy Gapon <avg@FreeBSD.org>
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--- src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h.orig 2012-12-19 19:27:29.000000000 +0100
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+++ src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h 2012-12-20 12:07:48.941861966 +0100
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@@ -82,6 +82,8 @@
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uint64_t cTicks = ASMMultU64ByU32DivByU32(uTimeout, hz, UINT32_C(1000000000));
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if (cTicks >= INT_MAX)
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return RTSEMWAIT_FLAGS_INDEFINITE;
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+ else if (cTicks == 0 && uTimeout > 0)
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+ pWait->iTimeout = 1;
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else
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pWait->iTimeout = (int)cTicks;
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#endif
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