Re: [Qemu-devel] [PATCH v5 1/9] Add cache handling functions

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On 01/04/2012 03:29 AM, Orit Wasserman wrote:
> On 01/03/2012 09:54 PM, Anthony Liguori wrote:
>> On 01/03/2012 09:34 AM, Orit Wasserman wrote:
>>> Add page caching mechanism.
>>> The pages are stored in the cache ordered by their address.
>>>
>>> Signed-off-by: Orit Wasserman<owasserm@redhat.com>
>>> ---
>>>    arch_init.c |  183 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>    1 files changed, 183 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/arch_init.c b/arch_init.c
>>> index d4c92b0..fdda277 100644
>>> --- a/arch_init.c
>>> +++ b/arch_init.c
>>> @@ -28,6 +28,7 @@
>>>    #include<sys/types.h>
>>>    #include<sys/mman.h>
>>>    #endif
>>> +#include<assert.h>
>>>    #include "config.h"
>>>    #include "monitor.h"
>>>    #include "sysemu.h"
>>> @@ -42,6 +43,14 @@
>>>    #include "gdbstub.h"
>>>    #include "hw/smbios.h"
>>>
>>> +#ifdef DEBUG_ARCH_INIT
>>> +#define DPRINTF(fmt, ...) \
>>> +    do { fprintf(stdout, "arch_init: " fmt, ## __VA_ARGS__); } while (0)
>>> +#else
>>> +#define DPRINTF(fmt, ...) \
>>> +    do { } while (0)
>>> +#endif
>>> +
>>>    #ifdef TARGET_SPARC
>>>    int graphic_width = 1024;
>>>    int graphic_height = 768;
>>> @@ -94,6 +103,180 @@ const uint32_t arch_type = QEMU_ARCH;
>>>    #define RAM_SAVE_FLAG_EOS      0x10
>>>    #define RAM_SAVE_FLAG_CONTINUE 0x20
>>>
>>> +/***********************************************************/
>>> +/* Page cache for storing previous pages as basis for XBRLE compression */
>>> +#define CACHE_N_WAY 2 /* 2-way assossiative cache */
>>
>> Is there any reason we can't just use a GCache for this?
>>
>> http://developer.gnome.org/glib/stable/glib-Caches.html
> I'm not familiar with I will check.
> Is it 2-way associative cache ?

Not quite...it's a very loose wrapper around GHashTable, which appears 
to be fully associative in nature. It also doesn't seem to allow you to 
do a lookup without destroying the table entry =\ (unless you do 
something hacky like an extra insert beforehand to jack up the 
refcount). If you go this route you're probably better off looking at 
GHashTable directly.

>
> Orit
>>
>> Regards,
>>
>> Anthony Liguori
>
>