-----Original Message-----
From: boost-users-bounces@lists.boost.org [mailto:boost-users-
bounces@lists.boost.org] On Behalf Of Beman Dawes
Sent: Thursday, December 16, 2004 4:19 PM
To: boost-users@lists.boost.org; boost-users@lists.boost.org
Subject: Re: [Boost-users] boost and memory allocations (signals and
others)
At 09:17 AM 12/15/2004, Caleb Epstein wrote:
On Mon, 13 Dec 2004 09:01:01 -0800, Frank Maddin
<frankmad@microsoft.com>
wrote:
We've been thinking about using certain boost functionality on a
project.
We were trying to keep the number of allocations down.
See the attached test program which makes the Hello class "noisy" and
runs two different versions of your signals test. One uses object
copy semantics and the other uses reference semantics. Compare the
output:
copy test:
Hello::Hello () @ 0xbfffb950
Hello::Hello (const ref) @ 0xbfffb8c0
Hello::Hello (const ref) @ 0xbfffb870
Hello::Hello (const ref) @ 0xbfffb830
Hello::Hello (const ref) @ 0xbfffb7e0
Hello::Hello (const ref) @ 0x8050fb0
Hello::~Hello @ 0xbfffb7e0
Hello::~Hello @ 0xbfffb830
Hello::~Hello @ 0xbfffb870
Hello::~Hello @ 0xbfffb8c0
Hello::Hello (const ref) @ 0x8050fc0
Hello::Hello (const ref) @ 0x8050fc8
Hello::Hello (const ref) @ 0x8050fd0
Hello::~Hello @ 0x8050fc8
Hello::~Hello @ 0x8050fc0
Hello::~Hello @ 0x8050fb0
i = 1968
Hello::~Hello @ 0x8050fd0
Hello::~Hello @ 0xbfffb950
ref test:
Hello::Hello () @ 0xbfffb950
i = 1968
Hello::~Hello @ 0xbfffb950
Wow! That is a pretty substantial difference.
Seems like the signals docs should make a point of explaining the
efficiency gained by using ref. Or maybe they do, but I didn't find
anything in several minutes of poking around the docs. There is no table
of
contents entry like "Efficiency considerations" or similar.
--Beman
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Thanks, that did indeed remove some churn. As Mr. Dawes pointed out, it would be nice to have that info in the docs somewhere. Overall though, I'm not sure that the allocations I'm seeing are acceptable for my application. Ideally, I'd like 1 allocation on connect and 0 allocations on signal send. We will be using an optimized small block allocator, but we still want to reduce memory operations as much as possible. Is there any suggestion to reduce this? I ran my own test putting in _CrtSetAllocHook(MyAllocHook), just copied from msdn. Below are the results (cleaned up a bit for just alloc hook calls). I haven't really looked at memory pools too closely. Would they be useful in any sort of situation with signals?
From the pool docs:
Pools are generally used when there is a lot of allocation and de-allocation of small objects. Another common usage
is the situation above, where many objects may be dropped out of memory.
Thanks, Frank ref test before declaration: Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 93) Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 95) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 96) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 97) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3240f8 Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 98) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 99) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 321688 Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 100) after declaration: before connect: Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 101) Memory operation in (null), line 0: allocating a 20-byte 'Normal' block (# 102) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 103) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 104) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 105) Memory operation in (null), line 0: allocating a 20-byte 'Normal' block (# 106) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 107) Memory operation in (null), line 0: allocating a 4-byte 'Normal' block (# 108) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 109) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 110) Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 111) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 112) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3244e0Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324490Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324340Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 321688Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324290Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3242e8 after connect: before sig send: Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 113) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 114) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 321688 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324490 after sig send: copy test: before declaration: Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 67) Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 69) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 70) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 71) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3240f8 Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 72) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 73) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 321688 Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 74) after declaration: before connect: Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 75) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 76) Memory operation in (null), line 0: allocating a 20-byte 'Normal' block (# 77) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 78) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 79) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 80) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 81) Memory operation in (null), line 0: allocating a 20-byte 'Normal' block (# 82) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 83) Memory operation in (null), line 0: allocating a 4-byte 'Normal' block (# 84) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 85) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 86) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 87) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 88) Memory operation in (null), line 0: allocating a 40-byte 'Normal' block (# 89) Memory operation in (null), line 0: allocating a 16-byte 'Normal' block (# 90) Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 91) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3245f0 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3245a0 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324560 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324510 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 32439 0Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324340 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3240f8 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 321688 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324290 Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 3242e8 after connect: before sig send: Memory operation in (null), line 0: allocating a 1-byte 'Normal' block (# 92) Memory operation in (null), line 0: allocating a 24-byte 'Normal' block (# 93) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) Memory operation in (null), line 0: freeing a 0-byte 'Normal' block (# 0) at 324510 after sig send: