Christopher Haster
8f2a6a3095
Now, when files are synced, they broadcast their disk changes to any other
opened file handles. In effect, all open files match disk after a sync
call to any opened file handle pointing to that file.
This was a much requested feature, as the previous behavior (multiple
opened file handles maintain independent snapshots) is pretty different
from other filesystems. It's also quite difficult to implement outside
of the filesystem, since you need to track all opened files, requiring
either unbounded RAM or a known upper limit.
---
A bit unrelated, but this commit also changes bshrub estimate
calculation to include all opened file handles. This adds some annoying
complexity, but is necessary to prevent sporadic ERANGE errors when
the same file is opened multiple times.
The current implementation just refetches on-disk metadata. This adds
some maybe unnecessary metadata lookups, but simplifies things by
avoiding the tracking of on-disk sprout/shrub size, which risks falling
out of date. Keep in mind we only recalculate the estimate every
~inline_size/2 bytes written.
Just like lfsr_mdir_estimate, this scales O(n^2) with the number of
opened files (this are basically the same function... hmmm... can they
be deduplicated?). This is unlikely to be a problem for littlefs's use
case, but just something to be aware of.
Code changes:
code stack
before: 32920 3032
after: 33192 (+0.8%) 3048 (+0.5%)
190 lines
6.4 KiB
C
190 lines
6.4 KiB
C
/*
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* Runner for littlefs benchmarks
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*
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* Copyright (c) 2022, The littlefs authors.
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#ifndef BENCH_RUNNER_H
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#define BENCH_RUNNER_H
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// override LFS_TRACE
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void bench_trace(const char *fmt, ...);
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#define LFS_TRACE_(fmt, ...) \
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bench_trace("%s:%d:trace: " fmt "%s\n", \
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__FILE__, \
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__LINE__, \
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__VA_ARGS__)
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#define LFS_TRACE(...) LFS_TRACE_(__VA_ARGS__, "")
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#define LFS_EMUBD_TRACE(...) LFS_TRACE_(__VA_ARGS__, "")
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// BENCH_START/BENCH_STOP macros measure readed/proged/erased bytes
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// through emubd
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void bench_start(const char *meas, uintmax_t iter, uintmax_t size);
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void bench_stop(const char *meas);
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#define BENCH_START(meas, iter, size) \
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bench_start(meas, iter, size)
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#define BENCH_STOP(meas) \
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bench_stop(meas)
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// BENCH_RESULT/BENCH_FRESULT allow for explicit non-io measurements
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void bench_result(const char *meas, uintmax_t iter, uintmax_t size,
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uintmax_t result);
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void bench_fresult(const char *meas, uintmax_t iter, uintmax_t size,
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double result);
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#define BENCH_RESULT(meas, iter, size, result) \
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bench_result(meas, iter, size, result)
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#define BENCH_FRESULT(meas, iter, size, result) \
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bench_fresult(meas, iter, size, result)
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// note these are indirectly included in any generated files
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#include "bd/lfs_emubd.h"
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#include <stdio.h>
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// give source a chance to define feature macros
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#undef _FEATURES_H
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#undef _STDIO_H
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// generated bench configurations
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struct lfs_config;
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enum bench_flags {
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BENCH_INTERNAL = 0x1,
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};
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typedef uint8_t bench_flags_t;
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typedef struct bench_define {
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intmax_t (*cb)(void *data, size_t i);
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void *data;
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size_t permutations;
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} bench_define_t;
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struct bench_case {
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const char *name;
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const char *path;
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bench_flags_t flags;
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const bench_define_t *defines;
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size_t permutations;
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bool (*if_)(void);
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void (*run)(struct lfs_config *cfg);
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};
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struct bench_suite {
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const char *name;
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const char *path;
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bench_flags_t flags;
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const char *const *define_names;
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size_t define_count;
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const struct bench_case *cases;
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size_t case_count;
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};
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extern const struct bench_suite *const bench_suites[];
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extern const size_t bench_suite_count;
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// deterministic prng for pseudo-randomness in benches
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uint32_t bench_prng(uint32_t *state);
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#define BENCH_PRNG(state) bench_prng(state)
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// generation of specific permutations of an array for exhaustive benching
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size_t bench_factorial(size_t x);
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void bench_permutation(size_t i, uint32_t *buffer, size_t size);
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#define BENCH_FACTORIAL(x) bench_factorial(x)
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#define BENCH_PERMUTATION(i, buffer, size) bench_permutation(i, buffer, size)
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// access generated bench defines
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intmax_t bench_define(size_t define);
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#define BENCH_DEFINE(i) bench_define(i)
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// a few preconfigured defines that control how benches run
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#define READ_SIZE_i 0
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#define PROG_SIZE_i 1
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#define BLOCK_SIZE_i 2
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#define BLOCK_COUNT_i 3
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#define DISK_SIZE_i 4
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#define CACHE_SIZE_i 5
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#define INLINE_SIZE_i 6
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#define SHRUB_SIZE_i 7
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#define FRAGMENT_SIZE_i 8
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#define CRYSTAL_THRESH_i 9
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#define LOOKAHEAD_SIZE_i 10
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#define BLOCK_CYCLES_i 11
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#define ERASE_VALUE_i 12
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#define ERASE_CYCLES_i 13
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#define BADBLOCK_BEHAVIOR_i 14
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#define POWERLOSS_BEHAVIOR_i 15
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#define BENCH_IMPLICIT_DEFINE_COUNT 16
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#define READ_SIZE bench_define(READ_SIZE_i)
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#define PROG_SIZE bench_define(PROG_SIZE_i)
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#define BLOCK_SIZE bench_define(BLOCK_SIZE_i)
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#define BLOCK_COUNT bench_define(BLOCK_COUNT_i)
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#define DISK_SIZE bench_define(DISK_SIZE_i)
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#define CACHE_SIZE bench_define(CACHE_SIZE_i)
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#define INLINE_SIZE bench_define(INLINE_SIZE_i)
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#define SHRUB_SIZE bench_define(SHRUB_SIZE_i)
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#define FRAGMENT_SIZE bench_define(FRAGMENT_SIZE_i)
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#define CRYSTAL_THRESH bench_define(CRYSTAL_THRESH_i)
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#define LOOKAHEAD_SIZE bench_define(LOOKAHEAD_SIZE_i)
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#define BLOCK_CYCLES bench_define(BLOCK_CYCLES_i)
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#define ERASE_VALUE bench_define(ERASE_VALUE_i)
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#define ERASE_CYCLES bench_define(ERASE_CYCLES_i)
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#define BADBLOCK_BEHAVIOR bench_define(BADBLOCK_BEHAVIOR_i)
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#define POWERLOSS_BEHAVIOR bench_define(POWERLOSS_BEHAVIOR_i)
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#define BENCH_IMPLICIT_DEFINES \
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/* name value (overridable) */ \
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BENCH_DEF(READ_SIZE, 1 ) \
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BENCH_DEF(PROG_SIZE, 1 ) \
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BENCH_DEF(BLOCK_SIZE, 4096 ) \
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BENCH_DEF(BLOCK_COUNT, DISK_SIZE/BLOCK_SIZE ) \
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BENCH_DEF(DISK_SIZE, 1024*1024 ) \
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BENCH_DEF(CACHE_SIZE, lfs_max(16, lfs_max(READ_SIZE, PROG_SIZE))) \
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BENCH_DEF(INLINE_SIZE, BLOCK_SIZE/4 ) \
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BENCH_DEF(SHRUB_SIZE, INLINE_SIZE ) \
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BENCH_DEF(FRAGMENT_SIZE, CACHE_SIZE ) \
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BENCH_DEF(CRYSTAL_THRESH, BLOCK_SIZE/8 ) \
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BENCH_DEF(LOOKAHEAD_SIZE, 16 ) \
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BENCH_DEF(BLOCK_CYCLES, -1 ) \
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BENCH_DEF(ERASE_VALUE, 0xff ) \
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BENCH_DEF(ERASE_CYCLES, 0 ) \
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BENCH_DEF(BADBLOCK_BEHAVIOR, LFS_EMUBD_BADBLOCK_PROGERROR ) \
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BENCH_DEF(POWERLOSS_BEHAVIOR, LFS_EMUBD_POWERLOSS_NOOP )
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#define BENCH_CFG \
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.read_size = READ_SIZE, \
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.prog_size = PROG_SIZE, \
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.block_size = BLOCK_SIZE, \
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.block_count = BLOCK_COUNT, \
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.block_cycles = BLOCK_CYCLES, \
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.cache_size = CACHE_SIZE, \
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.inline_size = INLINE_SIZE, \
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.shrub_size = SHRUB_SIZE, \
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.fragment_size = FRAGMENT_SIZE, \
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.crystal_thresh = CRYSTAL_THRESH, \
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.lookahead_size = LOOKAHEAD_SIZE,
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#define BENCH_BDCFG \
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.erase_value = ERASE_VALUE, \
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.erase_cycles = ERASE_CYCLES, \
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.badblock_behavior = BADBLOCK_BEHAVIOR,
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#endif
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