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chaos: add futex delays trait #2280

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chaos: add futex delays trait #2280

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b6a8eed
chaos: reimplement better random support
JakeHillion Oct 7, 2025
69434ac
chaos: add futex delays trait
JakeHillion Oct 9, 2025
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8 changes: 8 additions & 0 deletions scheds/include/scx/common.bpf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -763,6 +763,14 @@ static inline u64 scale_by_task_weight_inverse(const struct task_struct *p, u64
return value * 100 / p->scx.weight;
}

/*
* Get a random u64 from the kernel's pseudo-random generator.
*/
static inline u64 get_prandom_u64()
{
return ((u64)bpf_get_prandom_u32() << 32) | bpf_get_prandom_u32();
}


#include "compat.bpf.h"
#include "enums.bpf.h"
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14 changes: 11 additions & 3 deletions scheds/rust/scx_chaos/src/bpf/intf.h
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Expand Up @@ -10,10 +10,12 @@ typedef unsigned long long u64;
#endif

enum chaos_consts {
CHAOS_DSQ_BASE_SHIFT = 16,
CHAOS_DSQ_BASE = 1 << CHAOS_DSQ_BASE_SHIFT,
CHAOS_DSQ_BASE_SHIFT = 16,
CHAOS_DSQ_BASE = 1 << CHAOS_DSQ_BASE_SHIFT,

CHAOS_NUM_PPIDS_CHECK = 1 << 20,
CHAOS_NUM_PPIDS_CHECK = 1 << 20,

CHAOS_MAX_RAND_ATTEMPTS = 512,
};

enum chaos_match {
Expand All @@ -31,6 +33,7 @@ enum chaos_trait_kind {
CHAOS_TRAIT_CPU_FREQ,
CHAOS_TRAIT_DEGRADATION,
CHAOS_TRAIT_KPROBE_RANDOM_DELAYS,
CHAOS_TRAIT_FUTEX_DELAYS,
CHAOS_TRAIT_MAX,
};

Expand All @@ -42,12 +45,17 @@ struct chaos_task_ctx {
enum chaos_trait_kind pending_trait;
u64 enq_flags;
u64 p2dq_vtime;

// Futex delay state
u64 futex_uaddr;
};

enum chaos_stat_idx {
CHAOS_STAT_TRAIT_RANDOM_DELAYS,
CHAOS_STAT_TRAIT_CPU_FREQ,
CHAOS_STAT_TRAIT_DEGRADATION,
CHAOS_STAT_TRAIT_FUTEX_DELAYS,
CHAOS_STAT_TRAIT_FUTEX_DELAYS_CONTENDED,
CHAOS_STAT_CHAOS_EXCLUDED,
CHAOS_STAT_CHAOS_SKIPPED,
CHAOS_STAT_KPROBE_RANDOM_DELAYS,
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