source: libcfa/src/concurrency/kernel/cluster.hfa @ b035046

ADTast-experimentalpthread-emulationqualifiedEnum
Last change on this file since b035046 was b035046, checked in by Thierry Delisle <tdelisle@…>, 21 months ago

changed some MAX to ULLONG_MAX to avoid the memory access where possible and removed some -1u I missed last time

  • Property mode set to 100644
File size: 3.4 KB
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1//
2// Cforall Version 1.0.0 Copyright (C) 2022 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// cluster.hfa -- file that includes helpers for subsystem that need cluster wide support
8//
9// Author           : Thierry Delisle
10// Created On       : Tue Mar 15 16:40:12 2022
11// Last Modified By :
12// Last Modified On :
13// Update Count     :
14//
15
16#pragma once
17
18#include "device/cpu.hfa"
19#include "kernel/private.hfa"
20
21#include <limits.h>
22
23//-----------------------------------------------------------------------
24// Calc moving average based on existing average, before and current time.
25static inline unsigned long long moving_average(unsigned long long currtsc, unsigned long long instsc, unsigned long long old_avg) {
26        /* paranoid */ verifyf( currtsc < 45000000000000000, "Suspiciously large current time: %'llu (%llx)\n", currtsc, currtsc );
27        /* paranoid */ verifyf( instsc  < 45000000000000000, "Suspiciously large insert time: %'llu (%llx)\n", instsc, instsc );
28        /* paranoid */ verifyf( old_avg < 15000000000000, "Suspiciously large previous average: %'llu (%llx)\n", old_avg, old_avg );
29
30        const unsigned long long new_val = currtsc > instsc ? currtsc - instsc : 0;
31        const unsigned long long total_weight = 16;
32        const unsigned long long new_weight   = 4;
33        const unsigned long long old_weight = total_weight - new_weight;
34        const unsigned long long ret = ((new_weight * new_val) + (old_weight * old_avg)) / total_weight;
35        return ret;
36}
37
38static inline void touch_tsc(__timestamp_t * tscs, size_t idx, unsigned long long ts_prev, unsigned long long ts_next) {
39        if (ts_next == ULLONG_MAX) return;
40        unsigned long long now = rdtscl();
41        unsigned long long pma = __atomic_load_n(&tscs[ idx ].ma, __ATOMIC_RELAXED);
42        __atomic_store_n(&tscs[ idx ].tv, ts_next, __ATOMIC_RELAXED);
43        __atomic_store_n(&tscs[ idx ].ma, moving_average(now, ts_prev, pma), __ATOMIC_RELAXED);
44}
45
46//-----------------------------------------------------------------------
47// Calc age a timestamp should be before needing help.
48forall(Data_t * | { unsigned long long ts(Data_t & this); })
49static inline unsigned long long calc_cutoff(
50        const unsigned long long ctsc,
51        unsigned procid,
52        size_t count,
53        Data_t * data,
54        __timestamp_t * tscs,
55        const unsigned shard_factor
56) {
57        unsigned start = procid;
58        unsigned long long max = 0;
59        for(i; shard_factor) {
60                unsigned long long ptsc = ts(data[start + i]);
61                if(ptsc != ULLONG_MAX) {
62                        /* paranoid */ verify( start + i < count );
63                        unsigned long long tsc = moving_average(ctsc, ptsc, tscs[start + i].ma);
64                        if(tsc > max) max = tsc;
65                }
66        }
67        return (max + 2 * max) / 2;
68}
69
70static inline unsigned cache_id(struct cluster * cltr, unsigned idx) with (cltr->sched) {
71        // Figure out the current cpu and make sure it is valid
72        const int cpu = __kernel_getcpu();
73        /* paranoid */ verify(cpu >= 0);
74        /* paranoid */ verify(cpu < cpu_info.hthrd_count);
75        unsigned this_cache = cpu_info.llc_map[cpu].cache;
76
77        // Super important: don't write the same value over and over again
78        // We want to maximise our chances that his particular values stays in cache
79        if(caches[idx].id != this_cache)
80                __atomic_store_n(&caches[idx].id, this_cache, __ATOMIC_RELAXED);
81
82        return this_cache;
83}
84
85static struct {
86        const unsigned readyq;
87        const unsigned io;
88} __shard_factor = { 2, 1 };
89
90// Local Variables: //
91// mode: c //
92// tab-width: 4 //
93// End: //
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