Re: [dmidecode] [PATCH 1/2] dmidecode: Use the most appropriate unit for cache size

[Elliott, Robert (Persistent Memory)]

> -----Original Message-----
> From: dmidecode-devel <address@hidden>
> On Behalf Of Elliott, Robert (Persistent Memory)
> Sent: Monday, December 17, 2018 10:50 AM
> To: address@hidden
> Subject: Re: [dmidecode] [PATCH 1/2] dmidecode: Use the most appropriate
> unit for cache size
> 
> 
> 
> > -----Original Message-----
> > From: dmidecode-devel <dmidecode-devel-
> address@hidden>
> > On Behalf Of Jean Delvare
> > Sent: Tuesday, December 11, 2018 2:20 PM
> > To: address@hidden
> > Subject: [dmidecode] [PATCH 1/2] dmidecode: Use the most appropriate unit
> > for cache size
> >
> > As newer CPUs have larger and larger cache, using kB to represent the
> > cache size is getting less convenient. Reuse the same function we have
> > for system memory size so that large units will be used as
> > appropriate. For example, a cache size reported as "20 MB" looks nicer
> > than as "20480 kB".
> > -           if (code >= 0x8000)
> > -                   printf(" %u MB", code >> 4);
> > -           else
> > -                   printf(" %u kB", code << 6);
> > +           size.l = code << 6;
> > +           size.h = code >> 26;
> >     }
> >     else
> > -           printf(" %u kB", code);
> 
> The value might not be an integer multiple of the larger prefix; if so,
> then you should either use floating point to show the fractional number
> (my recommendation), or stick with the smaller prefix.
> 
> Consider using this opportunity to switch to the SI-recommended IEC-defined
> prefixes for binary multiples: KiB (1024) and MiB (1024*1024) rather than
> KB (1000) and MB (1000*1000).
> 
Here's some code I submitted to grub long ago to print the biggest unit
prefixes without rounding:

      if (size & 0xfffff)
       grub_printf (" %6" PRIuGRUB_UINT64_T "KiB", size >> 10);
      else if (size & 0x3fffffff)
       grub_printf (" %6" PRIuGRUB_UINT64_T "MiB", size >> 20);
      else if (size & 0xffffffffff)
       grub_printf (" %6" PRIuGRUB_UINT64_T "GiB", size >> 30);
      else if (size & 0x3ffffffffffff)
       grub_printf (" %6" PRIuGRUB_UINT64_T "TiB", size >> 40);
      else if (size & 0xfffffffffffffff)
       grub_printf (" %6" PRIuGRUB_UINT64_T "PiB", size >> 50);
      else
       grub_printf (" %6" PRIuGRUB_UINT64_T "EiB", size >> 60);