Rather than dynamically building a table to aid per level computations,
define a constant table at compile time. Omit both high and low
insignificant bits. Use one to three tree levels, depending on the
number of significant bits.
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.
Implement and test a JSON validation parser. Use the parser to validate
JSON output from malloc_stats_print(), with a significant subset of
supported output options.
This resolves#551.
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.
Move test extent hook code from the extent integration test into a
header, and normalize the out-of-band controls and introspection.
Also refactor the base unit test to use the header.
Add the MALLCTL_ARENAS_ALL cpp macro as a fixed index for use
in accessing the arena.<i>.{purge,decay,dss} and stats.arenas.<i>.*
mallctls, and deprecate access via the arenas.narenas index (to be
removed in 6.0.0).
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.
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.
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.
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.
rtree_node_init spinlocks the node, allocates, and then sets the node.
This is under heavy contention at the top of the tree if many threads
start to allocate at the same time.
Instead, take a per-rtree sleeping mutex to reduce spinning. Tested
both pthreads and osx OSSpinLock, and both reduce spinning adequately
Previous benchmark time:
./ttest1 500 100
~15s
New benchmark time:
./ttest1 500 100
.57s
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.
Instead, move the epoch backward in time. Additionally, add
nstime_monotonic() and use it in debug builds to assert that time only
goes backward if nstime_update() is using a non-monotonic time source.
pgi fails to compile math.c, reporting that `-INFINITY` in `pt_norm_expected[]`
is a "Non-constant" expression. A simplified version of this failure is:
```c
#include <math.h>
static double inf1, inf2 = INFINITY; // no complaints
static double inf3 = INFINITY; // suddenly INFINITY is "Non-constant"
int main() { }
```
```sh
PGC-S-0074-Non-constant expression in initializer (t.c: 4)
```
pgi errors on the declaration of inf3, and will compile fine if that line is
removed. I've reported this bug to pgi, but in the meantime I just switched to
using (DBL_MAX + DBL_MAX) to work around this bug.
rtree-based extent lookups remain more expensive than chunk-based run
lookups, but with this optimization the fast path slowdown is ~3 CPU
cycles per metadata lookup (on Intel Core i7-4980HQ), versus ~11 cycles
prior. The path caching speedup tends to degrade gracefully unless
allocated memory is spread far apart (as is the case when using a
mixture of sbrk() and mmap()).
This makes it possible to acquire short-term "ownership" of rtree
elements so that it is possible to read an extent pointer *and* read the
extent's contents with a guarantee that the element will not be modified
until the ownership is released. This is intended as a mechanism for
resolving rtree read/write races rather than as a way to lock extents.
Use pszind_t size classes rather than szind_t size classes, and always
reserve space for NPSIZES elements. This removes unused heaps that are
not multiples of the page size, and adds (currently) unused heaps for
all huge size classes, with the immediate benefit that the size of
arena_t allocations is constant (no longer dependent on chunk size).
These compute size classes and indices similarly to size2index(),
index2size() and s2u(), respectively, but using the subset of size
classes that are multiples of the page size. Note that pszind_t and
szind_t are not interchangeable.
b2c0d6322d (Add witness, a simple online
locking validator.) caused a broad propagation of tsd throughout the
internal API, but tsd_fetch() was designed to fail prior to tsd
bootstrapping. Fix this by splitting tsd_t into non-nullable tsd_t and
nullable tsdn_t, and modifying all internal APIs that do not critically
rely on tsd to take nullable pointers. Furthermore, add the
tsd_booted_get() function so that tsdn_fetch() can probe whether tsd
bootstrapping is complete and return NULL if not. All dangerous
conversions of nullable pointers are tsdn_tsd() calls that assert-fail
on invalid conversion.
Refactor ph to support configurable comparison functions. Use a cpp
macro code generation form equivalent to the rb macros so that pairing
heaps can be used for both run heaps and chunk heaps.
Remove per node parent pointers, and instead use leftmost siblings' prev
pointers to track parents.
Fix multi-pass sibling merging to iterate over intermediate results
using a FIFO, rather than a LIFO. Use this fixed sibling merging
implementation for both merge phases of the auxiliary twopass algorithm
(first merging the aux list, then replacing the root with its merged
children). This fixes both degenerate merge behavior and the potential
for deep recursion.
This regression was introduced by
6bafa6678f (Pairing heap).
This resolves#371.
Add missing stats.arenas.<i>.{dss,lg_dirty_mult,decay_time}
initialization.
Fix stats.arenas.<i>.{pactive,pdirty} to read under the protection of
the arena mutex.
Use a single uint64_t in nstime_t to store nanoseconds rather than using
struct timespec. This reduces fragility around conversions between long
and uint64_t, especially missing casts that only cause problems on
32-bit platforms.
This is an alternative to the existing ratio-based unused dirty page
purging, and is intended to eventually become the sole purging
mechanism.
Add mallctls:
- opt.purge
- opt.decay_time
- arena.<i>.decay
- arena.<i>.decay_time
- arenas.decay_time
- stats.arenas.<i>.decay_time
This resolves#325.
Fix heap profiling to distinguish among otherwise identical sample sites
with interposed resets (triggered via the "prof.reset" mallctl). This
bug could cause data structure corruption that would most likely result
in a segfault.
Fix arenas_cache_cleanup() to handle allocation/deallocation within the
application's thread-specific data cleanup functions even after
arenas_cache is torn down.
Create and use FMT* macros that are equivalent to the PRI* macros that
inttypes.h defines. This allows uniform use of the Unix-specific format
specifiers, e.g. "%zu", as well as avoiding Windows-specific definitions
of e.g. PRIu64.
Add ffs()/ffsl() support for compiling with gcc.
Extract compatibility definitions of ENOENT, EINVAL, EAGAIN, EPERM,
ENOMEM, and ENORANGE into include/msvc_compat/windows_extra.h and
use the file for tests as well as for core jemalloc code.
Add various function attributes to the exported functions to give the
compiler more information to work with during optimization, and also
specify throw() when compiling with C++ on Linux, in order to adequately
match what __THROW does in glibc.
This resolves#237.
Add mallctls:
- arenas.lg_dirty_mult is initialized via opt.lg_dirty_mult, and can be
modified to change the initial lg_dirty_mult setting for newly created
arenas.
- arena.<i>.lg_dirty_mult controls an individual arena's dirty page
purging threshold, and synchronously triggers any purging that may be
necessary to maintain the constraint.
- arena.<i>.chunk.purge allows the per arena dirty page purging function
to be replaced.
This resolves#93.
Migrate all centralized data structures related to huge allocations and
recyclable chunks into arena_t, so that each arena can manage huge
allocations and recyclable virtual memory completely independently of
other arenas.
Add chunk node caching to arenas, in order to avoid contention on the
base allocator.
Use chunks_rtree to look up huge allocations rather than a red-black
tree. Maintain a per arena unsorted list of huge allocations (which
will be needed to enumerate huge allocations during arena reset).
Remove the --enable-ivsalloc option, make ivsalloc() always available,
and use it for size queries if --enable-debug is enabled. The only
practical implications to this removal are that 1) ivsalloc() is now
always available during live debugging (and the underlying radix tree is
available during core-based debugging), and 2) size query validation can
no longer be enabled independent of --enable-debug.
Remove the stats.chunks.{current,total,high} mallctls, and replace their
underlying statistics with simpler atomically updated counters used
exclusively for gdump triggering. These statistics are no longer very
useful because each arena manages chunks independently, and per arena
statistics provide similar information.
Simplify chunk synchronization code, now that base chunk allocation
cannot cause recursive lock acquisition.
Add the MALLOCX_TCACHE() and MALLOCX_TCACHE_NONE macros, which can be
used in conjunction with the *allocx() API.
Add the tcache.create, tcache.flush, and tcache.destroy mallctls.
This resolves#145.
Recent huge allocation refactoring associates huge allocations with
arenas, but it remains necessary to quickly look up huge allocation
metadata during reallocation/deallocation. A global radix tree remains
a good solution to this problem, but locking would have become the
primary bottleneck after (upcoming) migration of chunk management from
global to per arena data structures.
This lock-free implementation uses double-checked reads to traverse the
tree, so that in the steady state, each read or write requires only a
single atomic operation.
This implementation also assures that no more than two tree levels
actually exist, through a combination of careful virtual memory
allocation which makes large sparse nodes cheap, and skipping the root
node on x64 (possible because the top 16 bits are all 0 in practice).
This feature makes it possible to toggle the gdump feature on/off during
program execution, whereas the the opt.prof_dump mallctl value can only
be set during program startup.
This resolves#72.
In addition to true/false, opt.junk can now be either "alloc" or "free",
giving applications the possibility of junking memory only on allocation
or deallocation.
This resolves#172.
Add per size class huge allocation statistics, and normalize various
stats:
- Change the arenas.nlruns type from size_t to unsigned.
- Add the arenas.nhchunks and arenas.hchunks.<i>.size mallctl's.
- Replace the stats.arenas.<i>.bins.<j>.allocated mallctl with
stats.arenas.<i>.bins.<j>.curregs .
- Add the stats.arenas.<i>.hchunks.<j>.nmalloc,
stats.arenas.<i>.hchunks.<j>.ndalloc,
stats.arenas.<i>.hchunks.<j>.nrequests, and
stats.arenas.<i>.hchunks.<j>.curhchunks mallctl's.
Add:
--with-lg-page
--with-lg-page-sizes
--with-lg-size-class-group
--with-lg-quantum
Get rid of STATIC_PAGE_SHIFT, in favor of directly setting LG_PAGE.
Fix various edge conditions exposed by the configure options.
atexit(3) can deadlock internally during its own initialization if
jemalloc calls atexit() during jemalloc initialization. Mitigate the
impact by restructuring prof initialization to avoid calling atexit()
unless the registered function will actually dump a final heap profile.
Additionally, disable prof_final by default so that this land mine is
opt-in rather than opt-out.
This resolves#144.
This avoids grabbing the base mutex, as a step towards fine-grained
locking for huge allocations. The thread cache also provides a tiny
(~3%) improvement for serial huge allocations.
Abstract arenas access to use arena_get() (or a0get() where appropriate)
rather than directly reading e.g. arenas[ind]. Prior to the addition of
the arenas.extend mallctl, the worst possible outcome of directly
accessing arenas was a stale read, but arenas.extend may allocate and
assign a new array to arenas.
Add a tsd-based arenas_cache, which amortizes arenas reads. This
introduces some subtle bootstrapping issues, with tsd_boot() now being
split into tsd_boot[01]() to support tsd wrapper allocation
bootstrapping, as well as an arenas_cache_bypass tsd variable which
dynamically terminates allocation of arenas_cache itself.
Promote a0malloc(), a0calloc(), and a0free() to be generally useful for
internal allocation, and use them in several places (more may be
appropriate).
Abstract arena->nthreads management and fix a missing decrement during
thread destruction (recent tsd refactoring left arenas_cleanup()
unused).
Change arena_choose() to propagate OOM, and handle OOM in all callers.
This is important for providing consistent allocation behavior when the
MALLOCX_ARENA() flag is being used. Prior to this fix, it was possible
for an OOM to result in allocation silently allocating from a different
arena than the one specified.
Normalize size classes to use the same number of size classes per size
doubling (currently hard coded to 4), across the intire range of size
classes. Small size classes already used this spacing, but in order to
support this change, additional small size classes now fill [4 KiB .. 16
KiB). Large size classes range from [16 KiB .. 4 MiB). Huge size
classes now support non-multiples of the chunk size in order to fill (4
MiB .. 16 MiB).
Fix tsd cleanup regressions that were introduced in
5460aa6f66 (Convert all tsd variables to
reside in a single tsd structure.). These regressions were twofold:
1) tsd_tryget() should never (and need never) return NULL. Rename it to
tsd_fetch() and simplify all callers.
2) tsd_*_set() must only be called when tsd is in the nominal state,
because cleanup happens during the nominal-->purgatory transition,
and re-initialization must not happen while in the purgatory state.
Add tsd_nominal() and use it as needed. Note that tsd_*{p,}_get()
can still be used as long as no re-initialization that would require
cleanup occurs. This means that e.g. the thread_allocated counter
can be updated unconditionally.
Implement/test/fix the opt.prof_thread_active_init,
prof.thread_active_init, and thread.prof.active mallctl's.
Test/fix the thread.prof.name mallctl.
Refactor opt_prof_active to be read-only and move mutable state into the
prof_active variable. Stop leaning on ctl-related locking for
protection.
Refactor permuted backtrace test allocation that was originally used
only by the prof_accum test, so that it can be used by other heap
profiling test binaries.
