kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/include/linux/sched_clock.h
..
..
@@ -1,14 +1,39 @@
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+/* SPDX-License-Identifier: GPL-2.0-only */
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 /*
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  * sched_clock.h: support for extending counters to full 64-bit ns counter
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- *
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License version 2 as
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- * published by the Free Software Foundation.
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  */
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 #ifndef LINUX_SCHED_CLOCK
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 #define LINUX_SCHED_CLOCK
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 #ifdef CONFIG_GENERIC_SCHED_CLOCK
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+/**
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+ * struct clock_read_data - data required to read from sched_clock()
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+ *
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+ * @epoch_ns:		sched_clock() value at last update
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+ * @epoch_cyc:		Clock cycle value at last update.
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+ * @sched_clock_mask:   Bitmask for two's complement subtraction of non 64bit
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+ *			clocks.
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+ * @read_sched_clock:	Current clock source (or dummy source when suspended).
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+ * @mult:		Multipler for scaled math conversion.
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+ * @shift:		Shift value for scaled math conversion.
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+ *
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+ * Care must be taken when updating this structure; it is read by
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+ * some very hot code paths. It occupies <=40 bytes and, when combined
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+ * with the seqcount used to synchronize access, comfortably fits into
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+ * a 64 byte cache line.
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+ */
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+struct clock_read_data {
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+	u64 epoch_ns;
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+	u64 epoch_cyc;
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+	u64 sched_clock_mask;
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+	u64 (*read_sched_clock)(void);
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+	u32 mult;
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+	u32 shift;
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+};
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+
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+extern struct clock_read_data *sched_clock_read_begin(unsigned int *seq);
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+extern int sched_clock_read_retry(unsigned int seq);
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+
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 extern void generic_sched_clock_init(void);
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 extern void sched_clock_register(u64 (*read)(void), int bits,