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mdbx: rework MADV_DONTNEED threshold.

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Change-Id: I99058b96e9c54c56d37c6c963b01cf18458d37ba
This commit is contained in:
Leonid Yuriev 2019-12-24 18:16:04 +03:00
parent f2fd2280e4
commit 53d5cb0151
1 changed files with 19 additions and 11 deletions
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30
src/elements/core.c
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@ -7465,21 +7465,29 @@ static int mdbx_sync_locked(MDBX_env *env, unsigned flags,
}
#endif /* MDBX_USE_VALGRIND */
#if defined(MADV_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 size_t largest_bytes = pgno2bytes(env, largest_pgno);
const size_t madvise_gap = (largest_bytes < 65536 * 256)
? 65536
: (largest_bytes > MEGABYTE * 4 * 256)
? MEGABYTE * 4
: largest_bytes >> 8;
const size_t discard_edge_bytes = bytes_align2os_bytes(
env,
(MDBX_RDONLY & (env->me_lck ? env->me_lck->mti_envmode : env->me_flags))
? largest_bytes
: largest_bytes + madvise_gap);
const pgno_t discard_edge_pgno = bytes2pgno(env, discard_edge_bytes);
const pgno_t prev_discarded_pgno = *env->me_discarded_tail;
if (prev_discarded_pgno >
largest_aligned2os_pgno +
/* 1M threshold to avoid unreasonable madvise() call */
bytes2pgno(env, MEGABYTE)) {
discard_edge_pgno +
/* threshold to avoid unreasonable frequent madvise() calls */
bytes2pgno(env, madvise_gap)) {
mdbx_notice("open-MADV_%s %u..%u", "DONTNEED", *env->me_discarded_tail,
largest_pgno);
*env->me_discarded_tail = largest_aligned2os_pgno;
*env->me_discarded_tail = discard_edge_pgno;
const size_t prev_discarded_bytes =
pgno2bytes(env, prev_discarded_pgno) & ~(env->me_os_psize - 1);
mdbx_ensure(env, prev_discarded_bytes > largest_aligned2os_bytes);
mdbx_ensure(env, prev_discarded_bytes > discard_edge_bytes);
int advise = MADV_DONTNEED;
#if defined(MADV_FREE) && \
0 /* MADV_FREE works for only anonymous vma at the moment */
@ -7487,8 +7495,8 @@ static int mdbx_sync_locked(MDBX_env *env, unsigned flags,
mdbx_linux_kernel_version > 0x04050000)
advise = MADV_FREE;
#endif /* MADV_FREE */
int err = madvise(env->me_map + largest_aligned2os_bytes,
prev_discarded_bytes - largest_aligned2os_bytes, advise)
int err = madvise(env->me_map + discard_edge_bytes,
prev_discarded_bytes - discard_edge_bytes, advise)
? ignore_enosys(errno)
: MDBX_SUCCESS;
if (unlikely(MDBX_IS_ERROR(err)))