Re: Heap memory issues for Embedded Systems
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- Subject: Re: Heap memory issues for Embedded Systems
- From: Luiz Henrique de Figueiredo <lhf@...>
- Date: Fri, 8 Jul 2005 07:25:49 -0300
> Has anyone instrumented Lua to see what block sizes are common? Or is this
> likely to vary from project to project? I'm thinking that a sub-allocator
> for the common cases (or at least a free list) could be a significant win.
I think it's likely to depend on the application because string and closure
structs are allocated with a varying tail. However, simple value structs are
likely to be the most frequent.
Here is the result of "lua /dev/null" for Lua 5.1w6. The first column is the
number of requests for a block of the size given in the second column. The
alloc function (to replace the one in lauxlib.c) is given at the end.
Running "lua life.lua" shows a different pattern, although the top 10 are
the same (in a slightly different order).
169 20
39 22
38 21
31 23
27 32
23 24
16 28
14 25
12 56
10 224
10 112
9 19
7 27
6 448
4 26
3 896
2 31
2 29
2 16
2 12
1 91
1 88
1 76
1 72
1 540
1 512
1 348
1 34
1 256
1 192
1 18
1 1792
1 17
1 128
1 1024
static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
static size_t total=0;
static int time=0;
void *optr=ptr;
(void)ud;
(void)osize;
++time;
if (nsize == 0) {
free(ptr);
total-=osize;
printf(">>> %p %p %8d - T=%d O=%d N=%d\n",ptr,optr,time,total,osize,nsize);
return NULL;
}
else {
total+=nsize-osize;
ptr=realloc(ptr, nsize);
printf(">>> %p %p %8d %c T=%d O=%d N=%d\n",ptr,optr,time,osize==0?'+':'=',total,osize,nsize);
return ptr;
}
}
--lhf