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mdbx: refine madvise(MADV_REMOVE_OR_FREE_OR_DONTNEED), add 256K threshold.

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Change-Id: I1fe314fa10062dca0870ec035454370bfacf20f0
This commit is contained in:
Leonid Yuriev
2019-10-12 00:29:41 +03:00
parent f6ba670cd0
commit e04ea50c18
1 changed files with 11 additions and 6 deletions
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17
src/elements/core.c
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@@ -6172,22 +6172,25 @@ static int mdbx_sync_locked(MDBX_env *env, unsigned flags,
pgno2bytes(env, edge - largest_pgno));
}
#endif /* MDBX_USE_VALGRIND */
#if defined(MADV_REMOVE_OR_FREE_OR_DONTNEED)
const size_t largest_aligned2os_bytes =
pgno_align2os_bytes(env, largest_pgno);
const pgno_t largest_aligned2os_pgno =
bytes2pgno(env, largest_aligned2os_bytes);
const pgno_t prev_discarded_pgno = *env->me_discarded_tail;
if (prev_discarded_pgno >
largest_aligned2os_pgno +
/* 256Kb threshold to avoid unreasonable madvise() call */
bytes2pgno(env, 256 * 1024)) {
*env->me_discarded_tail = largest_aligned2os_pgno;
if (prev_discarded_pgno > largest_aligned2os_pgno) {
const size_t prev_discarded_bytes =
pgno_align2os_bytes(env, prev_discarded_pgno);
mdbx_ensure(env, prev_discarded_bytes > largest_aligned2os_bytes);
#if defined(MADV_REMOVE_OR_FREE_OR_DONTNEED)
(void)madvise(env->me_map + largest_aligned2os_bytes,
prev_discarded_bytes - largest_aligned2os_bytes,
MADV_REMOVE_OR_FREE_OR_DONTNEED);
#endif /* MADV_REMOVE_OR_FREE_OR_DONTNEED */
}
#endif /* MADV_REMOVE_OR_FREE_OR_DONTNEED */
/* LY: check conditions to shrink datafile */
const pgno_t backlog_gap =
@@ -6540,18 +6543,20 @@ static int __cold mdbx_env_map(MDBX_env *env, const int is_exclusive,
: MADV_DONTDUMP);
#endif
#if defined(MADV_REMOVE_OR_FREE_OR_DONTNEED)
if (is_exclusive && (env->me_flags & MDBX_WRITEMAP) != 0) {
const size_t used_aligned2os_bytes =
mdbx_roundup2(usedsize, env->me_os_psize);
*env->me_discarded_tail = bytes2pgno(env, used_aligned2os_bytes);
if (used_aligned2os_bytes < env->me_mapsize) {
#if defined(MADV_REMOVE_OR_FREE_OR_DONTNEED)
(void)madvise(env->me_map + used_aligned2os_bytes,
env->me_mapsize - used_aligned2os_bytes,
MADV_REMOVE_OR_FREE_OR_DONTNEED);
}
}
#else
(void)is_exclusive;
#endif /* MADV_REMOVE_OR_FREE_OR_DONTNEED */
}
}
#ifdef POSIX_FADV_RANDOM
/* this also checks that the file size is valid for a particular FS */