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

[Michael Roth]

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<address@hidden>
> > > ---
> > >    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