Re: [Qemu-devel] virtual pc hash table vs physical pc hash table

[Xin Tong]

maybe one of the reasons of having the virtual pc hash table is that
the pc does not need to be tranlated to a physical pc which is used in
the physical pc hash table.


Xin


On Fri, Jan 20, 2012 at 1:24 AM, 陳韋任 <address@hidden> wrote:
> On Mon, Jan 02, 2012 at 07:11:41AM -0500, Xin Tong wrote:
>> In qemu, there is a virtual pc hash table and a physical pc hash
>> table. virtual pc hash table is used to find tbs until a context
>> switch. and physical pc hash table keeps all the translated tb.
>> virtual pc hash table is smaller, accessed with 12 bits and physical
>> pc hash table is bigger, accessed with 15 bits. the size in the hash
>> tables are the primary reasons for having 2 hash tables ?
>
>  I think not. tb_find_fast use the virtual pc as index to search 
> env->tb_jmp_cache,
> and check the result of tb_jmp_cache is sane or not. If something goes wrong, 
> it
> turns to call tb_find_slow to use physical pc to do a slow search. The size
> should not be the reason for having 2 hash tables.
>
> Regards,
> chenwj
>
> --
> Wei-Ren Chen (陳韋任)
> Computer Systems Lab, Institute of Information Science,
> Academia Sinica, Taiwan (R.O.C.)
> Tel:886-2-2788-3799 #1667
> Homepage: http://people.cs.nctu.edu.tw/~chenwj