136 lines
6.3 KiB
Text
136 lines
6.3 KiB
Text
nedalloc v1.05 15th June 2008:
|
|
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|
|
|
|
by Niall Douglas (http://www.nedprod.com/programs/portable/nedmalloc/)
|
|
|
|
Enclosed is nedalloc, an alternative malloc implementation for multiple
|
|
threads without lock contention based on dlmalloc v2.8.4. It is more
|
|
or less a newer implementation of ptmalloc2, the standard allocator in
|
|
Linux (which is based on dlmalloc v2.7.0) but also contains a per-thread
|
|
cache for maximum CPU scalability.
|
|
|
|
It is licensed under the Boost Software License which basically means
|
|
you can do anything you like with it. This does not apply to the malloc.c.h
|
|
file which remains copyright to others.
|
|
|
|
It has been tested on win32 (x86), win64 (x64), Linux (x64), FreeBSD (x64)
|
|
and Apple MacOS X (x86). It works very well on all of these and is very
|
|
significantly faster than the system allocator on all of these platforms.
|
|
|
|
By literally dropping in this allocator as a replacement for your system
|
|
allocator, you can see real world improvements of up to three times in normal
|
|
code!
|
|
|
|
To use:
|
|
-=-=-=-
|
|
Drop in nedmalloc.h, nedmalloc.c and malloc.c.h into your project.
|
|
Configure using the instructions in nedmalloc.h. Run and enjoy.
|
|
|
|
To test, compile test.c. It will run a comparison between your system
|
|
allocator and nedalloc and tell you how much faster nedalloc is. It also
|
|
serves as an example of usage.
|
|
|
|
Notes:
|
|
-=-=-=
|
|
If you want the very latest version of this allocator, get it from the
|
|
TnFOX SVN repository at svn://svn.berlios.de/viewcvs/tnfox/trunk/src/nedmalloc
|
|
|
|
Because of how nedalloc allocates an mspace per thread, it can cause
|
|
severe bloating of memory usage under certain allocation patterns.
|
|
You can substantially reduce this wastage by setting MAXTHREADSINPOOL
|
|
or the threads parameter to nedcreatepool() to a fraction of the number of
|
|
threads which would normally be in a pool at once. This will reduce
|
|
bloating at the cost of an increase in lock contention. If allocated size
|
|
is less than THREADCACHEMAX, locking is avoided 90-99% of the time and
|
|
if most of your allocations are below this value, you can safely set
|
|
MAXTHREADSINPOOL to one.
|
|
|
|
You will suffer memory leakage unless you call neddisablethreadcache()
|
|
per pool for every thread which exits. This is because nedalloc cannot
|
|
portably know when a thread exits and thus when its thread cache can
|
|
be returned for use by other code. Don't forget pool zero, the system pool.
|
|
|
|
For C++ type allocation patterns (where the same sizes of memory are
|
|
regularly allocated and deallocated as objects are created and destroyed),
|
|
the threadcache always benefits performance. If however your allocation
|
|
patterns are different, searching the threadcache may significantly slow
|
|
down your code - as a rule of thumb, if cache utilisation is below 80%
|
|
(see the source for neddisablethreadcache() for how to enable debug
|
|
printing in release mode) then you should disable the thread cache for
|
|
that thread. You can compile out the threadcache code by setting
|
|
THREADCACHEMAX to zero.
|
|
|
|
Speed comparisons:
|
|
-=-=-=-=-=-=-=-=-=
|
|
See Benchmarks.xls for details.
|
|
|
|
The enclosed test.c can do two things: it can be a torture test or a speed
|
|
test. The speed test is designed to be a representative synthetic
|
|
memory allocator test. It works by randomly mixing allocations with frees
|
|
with half of the allocation sizes being a two power multiple less than
|
|
512 bytes (to mimic C++ stack instantiated objects) and the other half
|
|
being a simple random value less than 16Kb.
|
|
|
|
The real world code results are from Tn's TestIO benchmark. This is a
|
|
heavily multithreaded and memory intensive benchmark with a lot of branching
|
|
and other stuff modern processors don't like so much. As you'll note, the
|
|
test doesn't show the benefits of the threadcache mostly due to the saturation
|
|
of the memory bus being the limiting factor.
|
|
|
|
ChangeLog:
|
|
-=-=-=-=-=
|
|
v1.05 15th June 2008:
|
|
* { 1042 } Added error check for TLSSET() and TLSFREE() macros. Thanks to
|
|
Markus Elfring for reporting this.
|
|
* { 1043 } Fixed a segfault when freeing memory allocated using
|
|
nedindependent_comalloc(). Thanks to Pavel Vozenilek for reporting this.
|
|
|
|
v1.04 14th July 2007:
|
|
* Fixed a bug with the new optimised implementation that failed to lock
|
|
on a realloc under certain conditions.
|
|
* Fixed lack of thread synchronisation in InitPool() causing pool corruption
|
|
* Fixed a memory leak of thread cache contents on disabling. Thanks to Earl
|
|
Chew for reporting this.
|
|
* Added a sanity check for freed blocks being valid.
|
|
* Reworked test.c into being a torture test.
|
|
* Fixed GCC assembler optimisation misspecification
|
|
|
|
v1.04alpha_svn915 7th October 2006:
|
|
* Fixed failure to unlock thread cache list if allocating a new list failed.
|
|
Thanks to Dmitry Chichkov for reporting this. Further thanks to Aleksey Sanin.
|
|
* Fixed realloc(0, <size>) segfaulting. Thanks to Dmitry Chichkov for
|
|
reporting this.
|
|
* Made config defines #ifndef so they can be overridden by the build system.
|
|
Thanks to Aleksey Sanin for suggesting this.
|
|
* Fixed deadlock in nedprealloc() due to unnecessary locking of preferred
|
|
thread mspace when mspace_realloc() always uses the original block's mspace
|
|
anyway. Thanks to Aleksey Sanin for reporting this.
|
|
* Made some speed improvements by hacking mspace_malloc() to no longer lock
|
|
its mspace, thus allowing the recursive mutex implementation to be removed
|
|
with an associated speed increase. Thanks to Aleksey Sanin for suggesting this.
|
|
* Fixed a bug where allocating mspaces overran its max limit. Thanks to
|
|
Aleksey Sanin for reporting this.
|
|
|
|
v1.03 10th July 2006:
|
|
* Fixed memory corruption bug in threadcache code which only appeared with >4
|
|
threads and in heavy use of the threadcache.
|
|
|
|
v1.02 15th May 2006:
|
|
* Integrated dlmalloc v2.8.4, fixing the win32 memory release problem and
|
|
improving performance still further. Speed is now up to twice the speed of v1.01
|
|
(average is 67% faster).
|
|
* Fixed win32 critical section implementation. Thanks to Pavel Kuznetsov
|
|
for reporting this.
|
|
* Wasn't locking mspace if all mspaces were locked. Thanks to Pavel Kuznetsov
|
|
for reporting this.
|
|
* Added Apple Mac OS X support.
|
|
|
|
v1.01 24th February 2006:
|
|
* Fixed multiprocessor scaling problems by removing sources of cache sloshing
|
|
* Earl Chew <earl_chew <at> agilent <dot> com> sent patches for the following:
|
|
1. size2binidx() wasn't working for default code path (non x86)
|
|
2. Fixed failure to release mspace lock under certain circumstances which
|
|
caused a deadlock
|
|
|
|
v1.00 1st January 2006:
|
|
* First release
|