🚀 go-pugleaf

"Torjei Kvinen" <torjei@hahaha_bluezone.no> schreef in bericht
news:3d88958d@newsgroups.borland.com...
> "Tony Werten" <a.werten@cs.unimaas.nl> wrote in message
>
> > in my chessprogram I have a large hashtable (256 MB)
>
> You may consider not to cache it at all? Take a look at VirtualAlloc and
> PAGE_NOCACHE.

I'm a little confused here.

I have:  hashtable:array[0..1] of tHashtableentry

How do I go on ?

Virtualalloc(hashtable,... ) or Virtualalloc(@hashtable,....) doesn't seem
to work

Tony

>
>
> > What happens when I acces this table ie how much is transferred to cache
?
>
> On Pentium (including PIII) it's 32 bytes. P4 has 64 bytes.
>
> This link contains some relevant info: (sorry about the word wrapping)
>
http://cedar.intel.com/cgi-bin/ids.dll/content/content.jsp?cntKey=Generic+Ed
> itorial%3a%3ap4_vs_p3&cntType=IDS_EDITORIAL&catCode=BDS
>
>
> > If this is more than 32 bytes, can I it force to not cache more ?
>
> No, it's all or nothing on page size (4 KBytes) boundaries.
>
>
> --
> Regards
> Torjei Kvinen
>
>
>

  tHashtableentry=record
     key:int64;
     score:integer;
     flags:cardinal;
  end;

>
> function AllocNoCacheMem(const Size : Integer) : Pointer;
> begin
>   Result := VirtualAlloc(nil, Size, MEM_COMMIT,
>                          PAGE_READWRITE or PAGE_NOCACHE);
> end;
>
> procedure FreeNoCacheMem(const Mem : Pointer);
> begin
>   VirtualFree(Mem, 0, MEM_RELEASE);
> end;
>
>
> type
>   tHashtable = array[0..1] of tHashtableentry;
>   pHashtable = ^tHashtable;
>
> var
>   Hashtable = pHashtable;

I suppose the = has to be a :  ?

>
> begin
>   Hashtable := AllocNoCacheMem(256*1024*1024);
>

At this point i can get hashtable[0],hashtable[1] but hashtable[3] gives a
"subrange expression violates subrange bounds"

What I want is fe hashtable[0,0] but then I get a "array type required"

If I change pHashtable=array of tHashtable then things go right until I
actually acces an entry.

Tony

>   ..
>
>   FreeNoCacheMem(Hashtable);
> end;
>
>
> --
> Regards
> Torjei Kvinen
>
>
>

"Tony Werten" <a.werten@cs.unimaas.nl> wrote in message

> > You may consider not to cache it at all? Take a look at VirtualAlloc and
> > PAGE_NOCACHE.
>
> I'm a little confused here.
>
> I have:  hashtable:array[0..1] of tHashtableentry


function AllocNoCacheMem(const Size : Integer) : Pointer;
begin
  Result := VirtualAlloc(nil, Size, MEM_COMMIT,
                         PAGE_READWRITE or PAGE_NOCACHE);
end;

procedure FreeNoCacheMem(const Mem : Pointer);
begin
  VirtualFree(Mem, 0, MEM_RELEASE);
end;


type
  tHashtable = array[0..1] of tHashtableentry;
  pHashtable = ^tHashtable;

var
  Hashtable = pHashtable;

begin
  Hashtable := AllocNoCacheMem(256*1024*1024);

  ..

  FreeNoCacheMem(Hashtable);
end;


--
Regards
Torjei Kvinen

"Tony Werten" <a.werten@cs.unimaas.nl> wrote in message

> I get an adress back but when I acces "hashtable^[0,0].key" I get an
> accesviolation.

You have to show us more of you are doing, and the definition of hashtable.

To find out if something is wrong with the memory allocated by VirtualAlloc,
you can try AllocMem (in SysUtils) or GetMem instead.


--
Regards
Torjei Kvinen

"Tony Werten" <a.werten@cs.unimaas.nl> wrote in message

> At this point i can get hashtable[0],hashtable[1] but hashtable[3] gives a
> "subrange expression violates subrange bounds"

type
  tHashtable = array[0..(MaxInt div SizeOf(tHashtableentry))-1] of
tHashtableentry;

Or you can turn of range checking, see {$RANGECHECKS OFF}


> What I want is fe hashtable[0,0] but then I get a "array type required"

This is a two dimensional table, current definition of tHashtable is only
one dimension?


> If I change pHashtable=array of tHashtable then things go right until I
> actually acces an entry.

Here is how you define a two dimensional table.

type
  tHashtable = array[0..4095, 0..4095] of tHashtableentry;


--
Regards
Torjei Kvinen

> This is a two dimensional table, current definition of tHashtable is only
> one dimension?
>
>
> > If I change pHashtable=array of tHashtable then things go right until I
> > actually acces an entry.

Thanks, I think I have the idea. You basicly lay the definition over the
reserved memoryspace ?

>
> Here is how you define a two dimensional table.
>
> type
>   tHashtable = array[0..4095, 0..4095] of tHashtableentry;

OK, but now for the dishwasher. I need array[0..x,0..1] but I won't know x
until runtime.

cheers,

Tony

>
>
> --
> Regards
> Torjei Kvinen
>
>
>

Managed to get it to work.

It makes exactly 0% difference :(((

Appearantly my cache gets killed in other places to.

Tony

"Tony Werten" <a.werten@cs.unimaas.nl> schreef in bericht
news:3d88e19b$2@newsgroups.borland.com...
>   tHashtableentry=record
>      key:int64;
>      score:integer;
>      flags:cardinal;
>   end;
>
> >
> > function AllocNoCacheMem(const Size : Integer) : Pointer;
> > begin
> >   Result := VirtualAlloc(nil, Size, MEM_COMMIT,
> >                          PAGE_READWRITE or PAGE_NOCACHE);
> > end;
> >
> > procedure FreeNoCacheMem(const Mem : Pointer);
> > begin
> >   VirtualFree(Mem, 0, MEM_RELEASE);
> > end;
> >
> >
> > type
> >   tHashtable = array[0..1] of tHashtableentry;
> >   pHashtable = ^tHashtable;
> >
> > var
> >   Hashtable = pHashtable;
>
> I suppose the = has to be a :  ?
>
> >
> > begin
> >   Hashtable := AllocNoCacheMem(256*1024*1024);
> >
>
> At this point i can get hashtable[0],hashtable[1] but hashtable[3] gives a
> "subrange expression violates subrange bounds"
>
> What I want is fe hashtable[0,0] but then I get a "array type required"
>
> If I change pHashtable=array of tHashtable then things go right until I
> actually acces an entry.
>
> Tony
>
> >   ..
> >
> >   FreeNoCacheMem(Hashtable);
> > end;
> >
> >
> > --
> > Regards
> > Torjei Kvinen
> >
> >
> >
>
>