Commit Graph

186 Commits

Author SHA1 Message Date
David Goldblatt
b407a65401 Add basic reentrancy-checking support, and allow arena_new to reenter.
This checks whether or not we're reentrant using thread-local data, and, if we
are, moves certain internal allocations to use arena 0 (which should be properly
initialized after bootstrapping).

The immediate thing this allows is spinning up threads in arena_new, which will
enable spinning up background threads there.
2017-04-07 14:10:27 -07:00
David Goldblatt
0a0fcd3e6a Add hooking functionality
This allows us to hook chosen functions and do interesting things there (in
particular: reentrancy checking).
2017-04-07 14:10:27 -07:00
Qi Wang
fde3e20cc0 Integrate auto tcache into TSD.
The embedded tcache is initialized upon tsd initialization.  The avail arrays
for the tbins will be allocated / deallocated accordingly during init / cleanup.

With this change, the pointer to the auto tcache will always be available, as
long as we have access to the TSD.  tcache_available() (called in tcache_get())
is provided to check if we should use tcache.
2017-04-07 09:55:14 -07:00
Qi Wang
9ed84b0d45 Add init function support to tsd members.
This will facilitate embedding tcache into tsd, which will require proper
initialization cannot be done via the static initializer.  Make tsd->rtree_ctx
to be initialized via rtree_ctx_data_init().
2017-04-04 00:19:21 -07:00
Jason Evans
07f4f93434 Move arena_slab_data_t's nfree into extent_t's e_bits.
Compact extent_t to 128 bytes on 64-bit systems by moving
arena_slab_data_t's nfree into extent_t's e_bits.

Cacheline-align extent_t structures so that they always cross the
minimum number of cacheline boundaries.

Re-order extent_t fields such that all fields except the slab bitmap
(and overlaid heap profiling context pointer) are in the first
cacheline.

This resolves #461.
2017-03-27 22:43:39 -07:00
Jason Evans
4020523f67 Fix a race in rtree_szind_slab_update() for RTREE_LEAF_COMPACT. 2017-03-27 13:22:36 -07:00
Jason Evans
c8021d01f6 Implement bitmap_ffu(), which finds the first unset bit. 2017-03-24 17:52:46 -07:00
Qi Wang
64c5f5c174 Added "stats.mutexes.reset" mallctl to reset all mutex stats.
Also switched from the term "lock" to "mutex".
2017-03-23 00:03:28 -07:00
Qi Wang
ca9074deff Added lock profiling and output for global locks (ctl, prof and base). 2017-03-23 00:03:28 -07:00
Qi Wang
a4f176af57 Output bin lock profiling results to malloc_stats.
Two counters are included for the small bins: lock contention rate, and
max lock waiting time.
2017-03-23 00:03:28 -07:00
Jason Evans
32e7cf51cd Further specialize arena_[s]dalloc() tcache fast path.
Use tsd_rtree_ctx() rather than tsdn_rtree_ctx() when tcache is
non-NULL, in order to avoid an extra branch (and potentially extra stack
space) in the fast path.
2017-03-22 18:33:32 -07:00
Jason Evans
0ee0e0c155 Implement compact rtree leaf element representation.
If a single virtual adddress pointer has enough unused bits to pack
{szind_t, extent_t *, bool, bool}, use a single pointer-sized field in
each rtree leaf element, rather than using three separate fields.  This
has little impact on access speed (fewer loads/stores, but more bit
twiddling), except that denser representation increases TLB
effectiveness.
2017-03-22 18:33:32 -07:00
Jason Evans
99d68445ef Incorporate szind/slab into rtree leaves.
Expand and restructure the rtree API such that all common operations can
be achieved with minimal work, regardless of whether the rtree leaf
fields are independent versus packed into a single atomic pointer.
2017-03-22 18:33:32 -07:00
Jason Evans
944c8a3383 Split rtree_elm_t into rtree_{node,leaf}_elm_t.
This allows leaf elements to differ in size from internal node elements.

In principle it would be more correct to use a different type for each
level of the tree, but due to implementation details related to atomic
operations, we use casts anyway, thus counteracting the value of
additional type correctness.  Furthermore, such a scheme would require
function code generation (via cpp macros), as well as either unwieldy
type names for leaves or type aliases, e.g.

  typedef struct rtree_elm_d2_s rtree_leaf_elm_t;

This alternate strategy would be more correct, and with less code
duplication, but probably not worth the complexity.
2017-03-22 18:33:32 -07:00
Jason Evans
e8921cf2eb Convert extent_t's usize to szind.
Rather than storing usize only for large (and prof-promoted)
allocations, store the size class index for allocations that reside
within the extent, such that the size class index is valid for all
extents that contain extant allocations, and invalid otherwise (mainly
to make debugging simpler).
2017-03-22 18:33:32 -07:00
Jason Evans
64e458f5cd Implement two-phase decay-based purging.
Split decay-based purging into two phases, the first of which uses lazy
purging to convert dirty pages to "muzzy", and the second of which uses
forced purging, decommit, or unmapping to convert pages to clean or
destroy them altogether.  Not all operating systems support lazy
purging, yet the application may provide extent hooks that implement
lazy purging, so care must be taken to dynamically omit the first phase
when necessary.

The mallctl interfaces change as follows:
- opt.decay_time --> opt.{dirty,muzzy}_decay_time
- arena.<i>.decay_time --> arena.<i>.{dirty,muzzy}_decay_time
- arenas.decay_time --> arenas.{dirty,muzzy}_decay_time
- stats.arenas.<i>.pdirty --> stats.arenas.<i>.p{dirty,muzzy}
- stats.arenas.<i>.{npurge,nmadvise,purged} -->
  stats.arenas.<i>.{dirty,muzzy}_{npurge,nmadvise,purged}

This resolves #521.
2017-03-15 13:13:47 -07:00
Qi Wang
ec532e2c5c Implement per-CPU arena.
The new feature, opt.percpu_arena, determines thread-arena association
dynamically based CPU id. Three modes are supported: "percpu", "phycpu"
and disabled.

"percpu" uses the current core id (with help from sched_getcpu())
directly as the arena index, while "phycpu" will assign threads on the
same physical CPU to the same arena. In other words, "percpu" means # of
arenas == # of CPUs, while "phycpu" has # of arenas == 1/2 * (# of
CPUs). Note that no runtime check on whether hyper threading is enabled
is added yet.

When enabled, threads will be migrated between arenas when a CPU change
is detected. In the current design, to reduce overhead from reading CPU
id, each arena tracks the thread accessed most recently. When a new
thread comes in, we will read CPU id and update arena if necessary.
2017-03-08 23:19:01 -08:00
Qi Wang
8721e19c04 Fix arena_prefork lock rank order for witness.
When witness is enabled, lock rank order needs to be preserved during
prefork, not only for each arena, but also across arenas. This change
breaks arena_prefork into further stages to ensure valid rank order
across arenas. Also changed test/unit/fork to use a manual arena to
catch this case.
2017-03-08 23:07:27 -08:00
Jason Evans
e201e24904 Perform delayed coalescing prior to purging.
Rather than purging uncoalesced extents, perform just enough incremental
coalescing to purge only fully coalesced extents.  In the absence of
cached extent reuse, the immediate versus delayed incremental purging
algorithms result in the same purge order.

This resolves #655.
2017-03-07 10:25:12 -08:00
David Goldblatt
d4ac7582f3 Introduce a backport of C11 atomics
This introduces a backport of C11 atomics.  It has four implementations; ranked
in order of preference, they are:
- GCC/Clang __atomic builtins
- GCC/Clang __sync builtins
- MSVC _Interlocked builtins
- C11 atomics, from <stdatomic.h>

The primary advantages are:
- Close adherence to the standard API gives us a defined memory model.
- Type safety: atomic objects are now separate types from non-atomic ones, so
  that it's impossible to mix up atomic and non-atomic updates (which is
  undefined behavior that compilers are starting to take advantage of).
- Efficiency: we can specify ordering for operations, avoiding fences and
  atomic operations on strongly ordered architectures (example:
  `atomic_write_u32(ptr, val);` involves a CAS loop, whereas
  `atomic_store(ptr, val, ATOMIC_RELEASE);` is a plain store.

This diff leaves in the current atomics API (implementing them in terms of the
backport).  This lets us transition uses over piecemeal.

Testing:
This is by nature hard to test. I've manually tested the first three options on
Linux on gcc by futzing with the #defines manually, on freebsd with gcc and
clang, on MSVC, and on OS X with clang.  All of these were x86 machines though,
and we don't have any test infrastructure set up for non-x86 platforms.
2017-03-03 13:40:59 -08:00
Jason Evans
fd058f572b Immediately purge cached extents if decay_time is 0.
This fixes a regression caused by
54269dc0ed (Remove obsolete
arena_maybe_purge() call.), as well as providing a general fix.

This resolves #665.
2017-03-02 19:43:06 -08:00
Jason Evans
8ac7937eb5 Remove remainder of mb (memory barrier).
This complements 94c5d22a4d (Remove mb.h,
which is unused).
2017-02-22 00:24:14 -08:00
Jason Evans
b0654b95ed Fix arena->stats.mapped accounting.
Mapped memory increases when extent_alloc_wrapper() succeeds, and
decreases when extent_dalloc_wrapper() is called (during purging).
2017-02-16 15:52:11 -08:00
Jason Evans
6b5cba4191 Convert arena->stats synchronization to atomics. 2017-02-16 09:39:46 -08:00
Jason Evans
fa2d64c94b Convert arena->prof_accumbytes synchronization to atomics. 2017-02-16 09:39:46 -08:00
Jason Evans
0721b895ff Do not generate unused tsd_*_[gs]et() functions.
This avoids a gcc diagnostic note:
    note: The ABI for passing parameters with 64-byte alignment has
    changed in GCC 4.6
This note related to the cacheline alignment of rtree_ctx_t, which was
introduced by 4a346f5593 (Replace rtree
path cache with LRU cache.).
2017-02-13 10:47:16 -08:00
Jason Evans
5f11830754 Replace spin_init() with SPIN_INITIALIZER. 2017-02-08 18:50:03 -08:00
Jason Evans
cdc240d501 Make non-essential inline rtree functions static functions. 2017-02-08 18:50:03 -08:00
Jason Evans
c511a44e99 Split rtree_elm_lookup_hard() out of rtree_elm_lookup().
Anything but a hit in the first element of the lookup cache is
expensive enough to negate the benefits of inlining.
2017-02-08 18:50:03 -08:00
Jason Evans
4a346f5593 Replace rtree path cache with LRU cache.
Rework rtree_ctx_t to encapsulate an rtree leaf LRU lookup cache rather
than a single-path element lookup cache.  The replacement is logically
much simpler, as well as slightly faster in the fast path case and less
prone to degraded performance during non-trivial sequences of lookups.
2017-02-08 18:50:03 -08:00
Jason Evans
d27f29b468 Disentangle arena and extent locking.
Refactor arena and extent locking protocols such that arena and
extent locks are never held when calling into the extent_*_wrapper()
API.  This requires extra care during purging since the arena lock no
longer protects the inner purging logic.  It also requires extra care to
protect extents from being merged with adjacent extents.

Convert extent_t's 'active' flag to an enumerated 'state', so that
retained extents are explicitly marked as such, rather than depending on
ring linkage state.

Refactor the extent collections (and their synchronization) for cached
and retained extents into extents_t.  Incorporate LRU functionality to
support purging.  Incorporate page count accounting, which replaces
arena->ndirty and arena->stats.retained.

Assert that no core locks are held when entering any internal
[de]allocation functions.  This is in addition to existing assertions
that no locks are held when entering external [de]allocation functions.

Audit and document synchronization protocols for all arena_t fields.

This fixes a potential deadlock due to recursive allocation during
gdump, in a similar fashion to b49c649bc1
(Fix lock order reversal during gdump.), but with a necessarily much
broader code impact.
2017-02-01 16:43:46 -08:00
Jason Evans
1b6e43507e Fix/refactor tcaches synchronization.
Synchronize tcaches with tcaches_mtx rather than ctl_mtx.  Add missing
synchronization for tcache flushing.  This bug was introduced by
1cb181ed63 (Implement explicit tcache
support.), which was first released in 4.0.0.
2017-02-01 16:43:46 -08:00
Jason Evans
d0e93ada51 Add witness_assert_depth[_to_rank]().
This makes it possible to make lock state assertions about precisely
which locks are held.
2017-02-01 16:43:46 -08:00
Jason Evans
1ff09534b5 Fix prof_realloc() regression.
Mostly revert the prof_realloc() changes in
498856f44a (Move slabs out of chunks.) so
that prof_free_sampled_object() is called when appropriate.  Leave the
prof_tctx_[re]set() optimization in place, but add an assertion to
verify that all eight cases are correctly handled.  Add a comment to
make clear the code ordering, so that the regression originally fixed by
ea8d97b897 (Fix
prof_{malloc,free}_sample_object() call order in prof_realloc().) is not
repeated.

This resolves #499.
2017-01-17 15:16:37 -08:00
Jason Evans
edf1bafb2b Implement arena.<i>.destroy .
Add MALLCTL_ARENAS_DESTROYED for accessing destroyed arena stats as an
analogue to MALLCTL_ARENAS_ALL.

This resolves #382.
2017-01-06 18:58:46 -08:00
Jason Evans
a0dd3a4483 Implement per arena base allocators.
Add/rename related mallctls:
- Add stats.arenas.<i>.base .
- Rename stats.arenas.<i>.metadata to stats.arenas.<i>.internal .
- Add stats.arenas.<i>.resident .

Modify the arenas.extend mallctl to take an optional (extent_hooks_t *)
argument so that it is possible for all base allocations to be serviced
by the specified extent hooks.

This resolves #463.
2016-12-26 18:08:28 -08:00
Jason Evans
a6e86810d8 Refactor purging and splitting/merging.
Split purging into lazy and forced variants.  Use the forced variant for
zeroing dss.

Add support for NULL function pointers as an opt-out mechanism for the
dalloc, commit, decommit, purge_lazy, purge_forced, split, and merge
fields of extent_hooks_t.

Add short-circuiting checks in large_ralloc_no_move_{shrink,expand}() so
that no attempt is made if splitting/merging is not supported.

This resolves #268.
2016-12-26 18:08:16 -08:00
Jason Evans
c1baa0a9b7 Add huge page configuration and pages_[no}huge().
Add the --with-lg-hugepage configure option, but automatically configure
LG_HUGEPAGE even if it isn't specified.

Add the pages_[no]huge() functions, which toggle huge page state via
madvise(..., MADV_[NO]HUGEPAGE) calls.
2016-12-26 17:59:34 -08:00
Jason Evans
bacb6afc6c Simplify arena_slab_regind().
Rewrite arena_slab_regind() to provide sufficient constant data for
the compiler to perform division strength reduction.  This replaces
more general manual strength reduction that was implemented before
arena_bin_info was compile-time-constant.  It would be possible to
slightly improve on the compiler-generated division code by taking
advantage of range limits that the compiler doesn't know about.
2016-12-23 10:34:34 -08:00
Jason Evans
a38acf716e Add extent serial numbers.
Add extent serial numbers and use them where appropriate as a sort key
that is higher priority than address, so that the allocation policy
prefers older extents.

This resolves #147.
2016-11-15 13:08:33 -08:00
Jason Evans
cda59f9970 Rename atomic_*_{uint32,uint64,u}() to atomic_*_{u32,u64,zu}().
This change conforms to naming conventions throughout the codebase.
2016-11-07 11:27:48 -08:00
Jason Evans
04b463546e Refactor prng to not use 64-bit atomics on 32-bit platforms.
This resolves #495.
2016-11-07 10:52:44 -08:00
Jason Evans
ea9961acdb Fix psz/pind edge cases.
Add an "over-size" extent heap in which to store extents which exceed
the maximum size class (plus cache-oblivious padding, if enabled).
Remove psz2ind_clamp() and use psz2ind() instead so that trying to
allocate the maximum size class can in principle succeed.  In practice,
this allows assertions to hold so that OOM errors can be successfully
generated.
2016-11-03 22:33:34 -07:00
Jason Evans
4f7d8c2dee Update symbol mangling. 2016-11-03 15:00:02 -07:00
Jason Evans
d9f7b2a430 Fix/refactor zone allocator integration code.
Fix zone_force_unlock() to reinitialize, rather than unlocking mutexes,
since OS X 10.12 cannot tolerate a child unlocking mutexes that were
locked by its parent.

Refactor; this was a side effect of experimenting with zone
{de,re}registration during fork(2).
2016-11-02 18:06:40 -07:00
Jason Evans
6a834d94bb Refactor witness_unlock() to fix undefined test behavior.
This resolves #396.
2016-10-31 11:49:12 -07:00
Jason Evans
b54d160dc4 Do not (recursively) allocate within tsd_fetch().
Refactor tsd so that tsdn_fetch() does not trigger allocation, since
allocation could cause infinite recursion.

This resolves #458.
2016-10-20 23:59:12 -07:00
Jason Evans
577d4572b0 Make dss operations lockless.
Rather than protecting dss operations with a mutex, use atomic
operations.  This has negligible impact on synchronization overhead
during typical dss allocation, but is a substantial improvement for
extent_in_dss() and the newly added extent_dss_mergeable(), which can be
called multiple times during extent deallocations.

This change also has the advantage of avoiding tsd in deallocation paths
associated with purging, which resolves potential deadlocks during
thread exit due to attempted tsd resurrection.

This resolves #425.
2016-10-13 15:37:00 -07:00
Jason Evans
9acd5cf178 Remove all vestiges of chunks.
Remove mallctls:
- opt.lg_chunk
- stats.cactive

This resolves #464.
2016-10-12 11:55:43 -07:00
Jason Evans
63b5657aa5 Remove ratio-based purging.
Make decay-based purging the default (and only) mode.

Remove associated mallctls:
- opt.purge
- opt.lg_dirty_mult
- arena.<i>.lg_dirty_mult
- arenas.lg_dirty_mult
- stats.arenas.<i>.lg_dirty_mult

This resolves #385.
2016-10-12 10:40:27 -07:00