On Wed, 20 Nov 2019 15:55:04 +0800
Tao Xu <tao3...@intel.com> wrote:
> On 11/19/2019 7:03 PM, Igor Mammedov wrote:
> > On Fri, 15 Nov 2019 15:53:46 +0800
> > Tao Xu <tao3...@intel.com> wrote:
> >
> >> From: Liu Jingqi <jingqi....@intel.com>
> >>
> >> Add -numa hmat-lb option to provide System Locality Latency and
> >> Bandwidth Information. These memory attributes help to build
> >> System Locality Latency and Bandwidth Information Structure(s)
> >> in ACPI Heterogeneous Memory Attribute Table (HMAT).
> >>
> >> Signed-off-by: Liu Jingqi <jingqi....@intel.com>
> >> Signed-off-by: Tao Xu <tao3...@intel.com>
> >
> > looks good to me, so
> >
> > Reviewed-by: Igor Mammedov <imamm...@redhat.com>
> >
> >
> > PS:
> > also see question below
> >
> [...]
> >> +
> >> + hmat_lb->range_bitmap |= node->bandwidth;
> >> + first_bit = ctz64(hmat_lb->range_bitmap);
> >> + hmat_lb->base = UINT64_C(1) << first_bit;
> >> + max_entry = node->bandwidth / hmat_lb->base;
> >> + last_bit = 64 - clz64(hmat_lb->range_bitmap);
> >> +
> >> + /*
> >> + * For bandwidth, first_bit record the base unit of bandwidth
> >> bits,
> >> + * last_bit record the last bit of the max bandwidth. The max
> >> compressed
> >> + * bandwidth should be less than 0xFFFF (UINT16_MAX)
> >> + */
> >> + if ((last_bit - first_bit) > UINT16_BITS || max_entry >=
> >> UINT16_MAX) {
> > ^^^^^^^^^^^^^^^^^^^
> > what bandwidth combination is going to trigger above condition?
> >
> Only use (last_bit - first_bit) > UINT16_BITS, we can't trigger error if
> the max compressed bandwidth is 0xFFFF. Because in that condition,
> "last_bit - first_bit == UINT16_BITS". So I add "max_entry >=
> UINT16_MAX" to catch 0xFFFF. For example:
>
> Combination 1 (Error):
> bandwidth1 = ...0000 1111 1111 1111 1110 0000... (max_entry 32767)
> range_bitmap = ...0000 1111 1111 1111 1110 0000... (range is 15 bits)
> bandwidth2 = ...0000 1111 1111 1111 1111 0000... (max_entry 65535)
> range_bitmap = ...0000 1111 1111 1111 1111 0000... (range is 16 bits)
>
> Combination 2 (Error):
> bandwidth1 = ...0000 1111 1111 1111 1110 0000... (max_entry 32767)
> range_bitmap = ...0000 1111 1111 1111 1110 0000... (range is 15 bits)
> bandwidth2 = ...0001 1111 1111 1111 1110 0000... (max_entry 65535)
> range_bitmap = ...0001 1111 1111 1111 1110 0000... (range is 16 bits)
>
> Combination 3 (OK, because bandwidth1 will be compressed to 65534):
> bandwidth1 = ...0000 1111 1111 1111 1110 0000... (max_entry 32767)
> range_bitmap = ...0000 1111 1111 1111 1110 0000... (range is 15 bits)
> bandwidth2 = ...0000 0111 1111 1111 1111 0000... (max_entry 32767)
> range_bitmap = ...0000 1111 1111 1111 1111 0000... (range is 16 bits)
>
> Combination 4 (Error):
> bandwidth1 = ...0000 1111 1111 1111 1111 0000... (max_entry 65535)
> range_bitmap = ...0000 1111 1111 1111 1111 0000... (range is 16 bits)
ok, I'd use in max/min possible values in bios-tables-test,
to make sure that we are testing whole range and would be able
to detect a error in case the valid ranges regressed (shrink)
and x-fail tests I've asked for in QMP test should detect
error other way around.
