Commit Graph

30 Commits

Author SHA1 Message Date
Daniel Micay
a95018ee81 Attempt to expand huge allocations in-place.
This adds support for expanding huge allocations in-place by requesting
memory at a specific address from the chunk allocator.

It's currently only implemented for the chunk recycling path, although
in theory it could also be done by optimistically allocating new chunks.
On Linux, it could attempt an in-place mremap. However, that won't work
in practice since the heap is grown downwards and memory is not unmapped
(in a normal build, at least).

Repeated vector reallocation micro-benchmark:

    #include <string.h>
    #include <stdlib.h>

    int main(void) {
        for (size_t i = 0; i < 100; i++) {
            void *ptr = NULL;
            size_t old_size = 0;
            for (size_t size = 4; size < (1 << 30); size *= 2) {
                ptr = realloc(ptr, size);
                if (!ptr) return 1;
                memset(ptr + old_size, 0xff, size - old_size);
                old_size = size;
            }
            free(ptr);
        }
    }

The glibc allocator fails to do any in-place reallocations on this
benchmark once it passes the M_MMAP_THRESHOLD (default 128k) but it
elides the cost of copies via mremap, which is currently not something
that jemalloc can use.

With this improvement, jemalloc still fails to do any in-place huge
reallocations for the first outer loop, but then succeeds 100% of the
time for the remaining 99 iterations. The time spent doing allocations
and copies drops down to under 5%, with nearly all of it spent doing
purging + faulting (when huge pages are disabled) and the array memset.

An improved mremap API (MREMAP_RETAIN - #138) would be far more general
but this is a portable optimization and would still be useful on Linux
for xallocx.

Numbers with transparent huge pages enabled:

glibc (copies elided via MREMAP_MAYMOVE): 8.471s

jemalloc: 17.816s
jemalloc + no-op madvise: 13.236s

jemalloc + this commit: 6.787s
jemalloc + this commit + no-op madvise: 6.144s

Numbers with transparent huge pages disabled:

glibc (copies elided via MREMAP_MAYMOVE): 15.403s

jemalloc: 39.456s
jemalloc + no-op madvise: 12.768s

jemalloc + this commit: 15.534s
jemalloc + this commit + no-op madvise: 6.354s

Closes #137
2014-10-05 14:47:01 -07:00
Jason Evans
551ebc4364 Convert to uniform style: cond == false --> !cond 2014-10-03 10:16:09 -07:00
Daniel Micay
f8034540a1 Implement in-place huge allocation shrinking.
Trivial example:

    #include <stdlib.h>

    int main(void) {
        void *ptr = malloc(1024 * 1024 * 8);
        if (!ptr) return 1;
        ptr = realloc(ptr, 1024 * 1024 * 4);
        if (!ptr) return 1;
    }

Before:

    mmap(NULL, 8388608, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fcfff000000
    mmap(NULL, 4194304, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fcffec00000
    madvise(0x7fcfff000000, 8388608, MADV_DONTNEED) = 0

After:

    mmap(NULL, 8388608, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f1934800000
    madvise(0x7f1934c00000, 4194304, MADV_DONTNEED) = 0

Closes #134
2014-10-01 16:55:03 -07:00
Jason Evans
5460aa6f66 Convert all tsd variables to reside in a single tsd structure. 2014-09-23 02:36:08 -07:00
Jason Evans
9c640bfdd4 Apply likely()/unlikely() to allocation/deallocation fast paths. 2014-09-11 17:01:58 -07:00
Jason Evans
b718cf77e9 Optimize [nmd]alloc() fast paths.
Optimize [nmd]alloc() fast paths such that the (flags == 0) case is
streamlined, flags decoding only happens to the minimum degree
necessary, and no conditionals are repeated.
2014-09-07 14:40:19 -07:00
Jason Evans
602c8e0971 Implement per thread heap profiling.
Rename data structures (prof_thr_cnt_t-->prof_tctx_t,
prof_ctx_t-->prof_gctx_t), and convert to storing a prof_tctx_t for
sampled objects.

Convert PROF_ALLOC_PREP() to prof_alloc_prep(), since precise backtrace
depth within jemalloc functions is no longer an issue (pprof prunes
irrelevant frames).

Implement mallctl's:
- prof.reset implements full sample data reset, and optional change of
  sample interval.
- prof.lg_sample reads the current sample interval (opt.lg_prof_sample
  was the permanent source of truth prior to prof.reset).
- thread.prof.name provides naming capability for threads within heap
  profile dumps.
- thread.prof.active makes it possible to activate/deactivate heap
  profiling for individual threads.

Modify the heap dump files to contain per thread heap profile data.
This change is incompatible with the existing pprof, which will require
enhancements to read and process the enriched data.
2014-08-19 21:31:16 -07:00
Jason Evans
e2deab7a75 Refactor huge allocation to be managed by arenas.
Refactor huge allocation to be managed by arenas (though the global
red-black tree of huge allocations remains for lookup during
deallocation).  This is the logical conclusion of recent changes that 1)
made per arena dss precedence apply to huge allocation, and 2) made it
possible to replace the per arena chunk allocation/deallocation
functions.

Remove the top level huge stats, and replace them with per arena huge
stats.

Normalize function names and types to *dalloc* (some were *dealloc*).

Remove the --enable-mremap option.  As jemalloc currently operates, this
is a performace regression for some applications, but planned work to
logarithmically space huge size classes should provide similar amortized
performance.  The motivation for this change was that mremap-based huge
reallocation forced leaky abstractions that prevented refactoring.
2014-05-15 22:36:41 -07:00
aravind
fb7fe50a88 Add support for user-specified chunk allocators/deallocators.
Add new mallctl endpoints "arena<i>.chunk.alloc" and
"arena<i>.chunk.dealloc" to allow userspace to configure
jemalloc's chunk allocator and deallocator on a per-arena
basis.
2014-05-12 10:46:03 -07:00
Jason Evans
4d434adb14 Make dss non-optional, and fix an "arena.<i>.dss" mallctl bug.
Make dss non-optional on all platforms which support sbrk(2).

Fix the "arena.<i>.dss" mallctl to return an error if "primary" or
"secondary" precedence is specified, but sbrk(2) is not supported.
2014-04-15 12:09:48 -07:00
Max Wang
fbb31029a5 Use arena dss prec instead of default for huge allocs.
Pass a dss_prec_t parameter to huge_{m,p,r}alloc instead of defaulting
to the chunk dss prec.
2014-03-28 13:43:58 -07:00
Jason Evans
940fdfd5ee Fix junk filling for mremap(2)-based huge reallocation.
If mremap(2) is used for huge reallocation, physical pages are mapped to
new virtual addresses rather than data being copied to new pages.  This
bypasses the normal junk filling that would happen during allocation, so
add junk filling that is specific to this case.
2014-02-25 12:37:25 -08:00
Jason Evans
b2c31660be Extract profiling code from [re]allocation functions.
Extract profiling code from malloc(), imemalign(), calloc(), realloc(),
mallocx(), rallocx(), and xallocx().  This slightly reduces the amount
of code compiled into the fast paths, but the primary benefit is the
combinatorial complexity reduction.

Simplify iralloc[t]() by creating a separate ixalloc() that handles the
no-move cases.

Further simplify [mrxn]allocx() (and by implication [mrn]allocm()) to
make request size overflows due to size class and/or alignment
constraints trigger undefined behavior (detected by debug-only
assertions).

Report ENOMEM rather than EINVAL if an OOM occurs during heap profiling
backtrace creation in imemalign().  This bug impacted posix_memalign()
and aligned_alloc().
2014-01-12 15:41:05 -08:00
Jason Evans
6b694c4d47 Add junk/zero filling unit tests, and fix discovered bugs.
Fix growing large reallocation to junk fill new space.

Fix huge deallocation to junk fill when munmap is disabled.
2014-01-07 16:54:17 -08:00
Jason Evans
6e62984ef6 Don't junk-fill reallocations unless usize changes.
Don't junk fill reallocations for which the request size is less than
the current usable size, but not enough smaller to cause a size class
change.  Unlike malloc()/calloc()/realloc(), *allocx() contractually
treats the full usize as the allocation, so a caller can ask for zeroed
memory via mallocx() and a series of rallocx() calls that all specify
MALLOCX_ZERO, and be assured that all newly allocated bytes will be
zeroed and made available to the application without danger of allocator
mutation until the size class decreases enough to cause usize reduction.
2013-12-15 21:57:09 -08:00
Jason Evans
d82a5e6a34 Implement the *allocx() API.
Implement the *allocx() API, which is a successor to the *allocm() API.
The *allocx() functions are slightly simpler to use because they have
fewer parameters, they directly return the results of primary interest,
and mallocx()/rallocx() avoid the strict aliasing pitfall that
allocm()/rallocx() share with posix_memalign().  The following code
violates strict aliasing rules:

    foo_t *foo;
    allocm((void **)&foo, NULL, 42, 0);

whereas the following is safe:

    foo_t *foo;
    void *p;
    allocm(&p, NULL, 42, 0);
    foo = (foo_t *)p;

mallocx() does not have this problem:

    foo_t *foo = (foo_t *)mallocx(42, 0);
2013-12-12 22:35:52 -08:00
Jason Evans
2a83ed0284 Refactor tests.
Refactor tests to use explicit testing assertions, rather than diff'ing
test output.  This makes the test code a bit shorter, more explicitly
encodes testing intent, and makes test failure diagnosis more
straightforward.
2013-12-08 20:52:21 -08:00
Jason Evans
609ae595f0 Add arena-specific and selective dss allocation.
Add the "arenas.extend" mallctl, so that it is possible to create new
arenas that are outside the set that jemalloc automatically multiplexes
threads onto.

Add the ALLOCM_ARENA() flag for {,r,d}allocm(), so that it is possible
to explicitly allocate from a particular arena.

Add the "opt.dss" mallctl, which controls the default precedence of dss
allocation relative to mmap allocation.

Add the "arena.<i>.dss" mallctl, which makes it possible to set the
default dss precedence on a per arena or global basis.

Add the "arena.<i>.purge" mallctl, which obsoletes "arenas.purge".

Add the "stats.arenas.<i>.dss" mallctl.
2012-10-12 18:26:16 -07:00
Jason Evans
2e671ffbad Add the --enable-mremap option.
Add the --enable-mremap option, and disable the use of mremap(2) by
default, for the same reason that freeing chunks via munmap(2) is
disabled by default on Linux: semi-permanent VM map fragmentation.
2012-05-09 16:12:00 -07:00
Mike Hommey
a14bce85e8 Use Get/SetLastError on Win32
Using errno on win32 doesn't quite work, because the value set in a shared
library can't be read from e.g. an executable calling the function setting
errno.

At the same time, since buferror always uses errno/GetLastError, don't pass
it.
2012-04-30 16:50:55 -07:00
Jason Evans
7ad54c1c30 Fix chunk allocation/deallocation bugs.
Fix chunk_alloc_dss() to zero memory when requested.

Fix chunk_dealloc() to avoid chunk_dealloc_mmap() for dss-allocated
memory.

Fix huge_palloc() to always junk fill when requested.

Improve chunk_recycle() to report that memory is zeroed as a side effect
of pages_purge().
2012-04-21 16:04:51 -07:00
Jason Evans
122449b073 Implement Valgrind support, redzones, and quarantine.
Implement Valgrind support, as well as the redzone and quarantine
features, which help Valgrind detect memory errors.  Redzones are only
implemented for small objects because the changes necessary to support
redzones around large and huge objects are complicated by in-place
reallocation, to the point that it isn't clear that the maintenance
burden is worth the incremental improvement to Valgrind support.

Merge arena_salloc() and arena_salloc_demote().

Refactor i[v]salloc() to expose the 'demote' option.
2012-04-11 11:46:18 -07:00
Mike Hommey
eae269036c Add alignment support to chunk_alloc(). 2012-04-10 14:51:39 -07:00
Jason Evans
4e2e3dd9cf Fix fork-related bugs.
Acquire/release arena bin locks as part of the prefork/postfork.  This
bug made deadlock in the child between fork and exec a possibility.

Split jemalloc_postfork() into jemalloc_postfork_{parent,child}() so
that the child can reinitialize mutexes rather than unlocking them.  In
practice, this bug tended not to cause problems.
2012-03-13 16:31:41 -07:00
Jason Evans
d81e4bdd5c Implement malloc_vsnprintf().
Implement malloc_vsnprintf() (a subset of vsnprintf(3)) as well as
several other printing functions based on it, so that formatted printing
can be relied upon without concern for inducing a dependency on floating
point runtime support.  Replace malloc_write() calls with
malloc_*printf() where doing so simplifies the code.

Add name mangling for library-private symbols in the data and BSS
sections.  Adjust CONF_HANDLE_*() macros in malloc_conf_init() to expose
all opt_* variable use to cpp so that proper mangling occurs.
2012-03-07 16:19:19 -08:00
Jason Evans
4162627757 Remove the swap feature.
Remove the swap feature, which enabled per application swap files.  In
practice this feature has not proven itself useful to users.
2012-02-13 10:56:17 -08:00
Jason Evans
7372b15a31 Reduce cpp conditional logic complexity.
Convert configuration-related cpp conditional logic to use static
constant variables, e.g.:

  #ifdef JEMALLOC_DEBUG
    [...]
  #endif

becomes:

  if (config_debug) {
    [...]
  }

The advantage is clearer, more concise code.  The main disadvantage is
that data structures no longer have conditionally defined fields, so
they pay the cost of all fields regardless of whether they are used.  In
practice, this is only a minor concern; config_stats will go away in an
upcoming change, and config_prof is the only other major feature that
depends on more than a few special-purpose fields.
2012-02-10 20:22:09 -08:00
Jason Evans
12a4887826 Fix huge_ralloc to maintain chunk statistics.
Fix huge_ralloc() to properly maintain chunk statistics when using
mremap(2).
2011-11-11 14:41:59 -08:00
Jason Evans
fa351d9fdc Fix huge_ralloc() race when using mremap(2).
Fix huge_ralloc() to remove the old memory region from tree of huge
allocations *before* calling mremap(2), in order to make sure that no
other thread acquires the old memory region via mmap() and encounters
stale metadata in the tree.

Reported by: Rich Prohaska
2011-11-09 11:55:19 -08:00
Jason Evans
7427525c28 Move repo contents in jemalloc/ to top level. 2011-03-31 20:36:17 -07:00