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In atomic backoff and cpu_relax(), use the pause instruction found on SPARC-T4 and later. It makes the cpu strand unselectable for the given number of cycles, unless an intervening disrupting trap occurs. Signed-off-by: David S. Miller <davem@davemloft.net>
46 lines
821 B
C
46 lines
821 B
C
#ifndef _SPARC64_BACKOFF_H
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#define _SPARC64_BACKOFF_H
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#define BACKOFF_LIMIT (4 * 1024)
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#ifdef CONFIG_SMP
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#define BACKOFF_SETUP(reg) \
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mov 1, reg
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#define BACKOFF_LABEL(spin_label, continue_label) \
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spin_label
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#define BACKOFF_SPIN(reg, tmp, label) \
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mov reg, tmp; \
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88: rd %ccr, %g0; \
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rd %ccr, %g0; \
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rd %ccr, %g0; \
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.section .pause_patch,"ax"; \
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.word 88b; \
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sllx tmp, 7, tmp; \
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wr tmp, 0, %asr27; \
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clr tmp; \
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.previous; \
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brnz,pt tmp, 88b; \
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sub tmp, 1, tmp; \
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set BACKOFF_LIMIT, tmp; \
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cmp reg, tmp; \
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bg,pn %xcc, label; \
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nop; \
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ba,pt %xcc, label; \
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sllx reg, 1, reg;
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#else
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#define BACKOFF_SETUP(reg)
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#define BACKOFF_LABEL(spin_label, continue_label) \
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continue_label
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#define BACKOFF_SPIN(reg, tmp, label)
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#endif
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#endif /* _SPARC64_BACKOFF_H */
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