* [PATCH v4 02/11] x86/intel_pstate: add some calculation related support
@ 2015-06-25 11:14 Wei Wang
2015-07-24 13:16 ` Jan Beulich
2015-07-24 13:17 ` Jan Beulich
0 siblings, 2 replies; 5+ messages in thread
From: Wei Wang @ 2015-06-25 11:14 UTC (permalink / raw)
To: jbeulich, andrew.cooper3, xen-devel; +Cc: Wei Wang
The added calculation related functions will be used in the intel_pstate.c.
They are copied from the Linux kernel(commit 2418f4f2, f3002134, eb18cba7).
v4 changes:
1) in commit message, "kernel" changed to "Linux kernel"
2) if-else coding style change.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
xen/include/asm-x86/div64.h | 78 +++++++++++++++++++++++++++++++++++++++++++++
xen/include/xen/kernel.h | 12 +++++++
2 files changed, 90 insertions(+)
diff --git a/xen/include/asm-x86/div64.h b/xen/include/asm-x86/div64.h
index dd49f64..1f171ba 100644
--- a/xen/include/asm-x86/div64.h
+++ b/xen/include/asm-x86/div64.h
@@ -11,4 +11,82 @@
__rem; \
})
+static inline uint64_t div_u64_rem(uint64_t dividend, uint32_t divisor,
+ uint32_t *remainder)
+{
+ *remainder = do_div(dividend, divisor);
+ return dividend;
+}
+
+static inline uint64_t div_u64(uint64_t dividend, uint32_t divisor)
+{
+ uint32_t remainder;
+
+ return div_u64_rem(dividend, divisor, &remainder);
+}
+
+/*
+ * div64_u64 - unsigned 64bit divide with 64bit divisor
+ * @dividend: 64bit dividend
+ * @divisor: 64bit divisor
+ *
+ * This implementation is a modified version of the algorithm proposed
+ * by the book 'Hacker's Delight'. The original source and full proof
+ * can be found here and is available for use without restriction.
+ *
+ * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt'
+ */
+static inline uint64_t div64_u64(uint64_t dividend, uint64_t divisor)
+{
+ uint32_t high = divisor >> 32;
+ uint64_t quot;
+
+ if (high == 0)
+ quot = div_u64(dividend, divisor);
+ else
+ {
+ int n = 1 + fls(high);
+ quot = div_u64(dividend >> n, divisor >> n);
+
+ if (quot != 0)
+ quot--;
+ if ((dividend - quot * divisor) >= divisor)
+ quot++;
+ }
+ return quot;
+}
+
+static inline int64_t div_s64_rem(int64_t dividend, int32_t divisor,
+ int32_t *remainder)
+{
+ int64_t quotient;
+
+ if (dividend < 0)
+ {
+ quotient = div_u64_rem(-dividend, ABS(divisor),
+ (uint32_t *)remainder);
+ *remainder = -*remainder;
+ if (divisor > 0)
+ quotient = -quotient;
+ }
+ else
+ {
+ quotient = div_u64_rem(dividend, ABS(divisor),
+ (uint32_t *)remainder);
+ if (divisor < 0)
+ quotient = -quotient;
+ }
+ return quotient;
+}
+
+/*
+ * div_s64 - signed 64bit divide with 32bit divisor
+ */
+static inline int64_t div_s64(int64_t dividend, int32_t divisor)
+{
+ int32_t remainder;
+
+ return div_s64_rem(dividend, divisor, &remainder);
+}
+
#endif
diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
index 548b64d..bfdcdb6 100644
--- a/xen/include/xen/kernel.h
+++ b/xen/include/xen/kernel.h
@@ -42,6 +42,18 @@
#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
+/*
+ * clamp_t - return a value clamped to a given range using a given type
+ * @type: the type of variable to use
+ * @val: current value
+ * @lo: minimum allowable value
+ * @hi: maximum allowable value
+ *
+ * This macro does no typechecking and uses temporary variables of type
+ * 'type' to make all the comparisons.
+ */
+#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
+
/**
* container_of - cast a member of a structure out to the containing structure
*
--
1.9.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v4 02/11] x86/intel_pstate: add some calculation related support
2015-06-25 11:14 [PATCH v4 02/11] x86/intel_pstate: add some calculation related support Wei Wang
@ 2015-07-24 13:16 ` Jan Beulich
2015-07-27 5:48 ` Wang, Wei W
2015-07-24 13:17 ` Jan Beulich
1 sibling, 1 reply; 5+ messages in thread
From: Jan Beulich @ 2015-07-24 13:16 UTC (permalink / raw)
To: Wei Wang; +Cc: andrew.cooper3, xen-devel
>>> On 25.06.15 at 13:14, <wei.w.wang@intel.com> wrote:
> The added calculation related functions will be used in the intel_pstate.c.
> They are copied from the Linux kernel(commit 2418f4f2, f3002134, eb18cba7).
>
> v4 changes:
> 1) in commit message, "kernel" changed to "Linux kernel"
> 2) if-else coding style change.
Despite of this, ...
> +static inline uint64_t div64_u64(uint64_t dividend, uint64_t divisor)
> +{
> + uint32_t high = divisor >> 32;
> + uint64_t quot;
> +
> + if (high == 0)
... this and further if()-s below are still not in line with ./CODING_STYLE
(missing blanks inside parentheses).
> + quot = div_u64(dividend, divisor);
> + else
> + {
> + int n = 1 + fls(high);
> + quot = div_u64(dividend >> n, divisor >> n);
Blank line between declaration(s) and statement(s) please.
> --- a/xen/include/xen/kernel.h
> +++ b/xen/include/xen/kernel.h
> @@ -42,6 +42,18 @@
> #define MIN(x,y) ((x) < (y) ? (x) : (y))
> #define MAX(x,y) ((x) > (y) ? (x) : (y))
>
> +/*
> + * clamp_t - return a value clamped to a given range using a given type
> + * @type: the type of variable to use
> + * @val: current value
> + * @lo: minimum allowable value
> + * @hi: maximum allowable value
> + *
> + * This macro does no typechecking and uses temporary variables of type
> + * 'type' to make all the comparisons.
> + */
> +#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
Shouldn't you also add a type checking variant then (which ought
to be used instead of the one above wherever possible)?
Jan
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v4 02/11] x86/intel_pstate: add some calculation related support
2015-07-24 13:16 ` Jan Beulich
@ 2015-07-27 5:48 ` Wang, Wei W
2015-08-11 10:07 ` Jan Beulich
0 siblings, 1 reply; 5+ messages in thread
From: Wang, Wei W @ 2015-07-27 5:48 UTC (permalink / raw)
To: Jan Beulich; +Cc: andrew.cooper3, xen-devel
> > +/*
> > + * clamp_t - return a value clamped to a given range using a given
> > +type
> > + * @type: the type of variable to use
> > + * @val: current value
> > + * @lo: minimum allowable value
> > + * @hi: maximum allowable value
> > + *
> > + * This macro does no typechecking and uses temporary variables of
> > +type
> > + * 'type' to make all the comparisons.
> > + */
> > +#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo),
> > +hi)
>
> Shouldn't you also add a type checking variant then (which ought to be used
> instead of the one above wherever possible)?
>
Hi Jan, I think the max_t() and min_t() have handled the typechecking thing, maybe we do not need to do it again here.
If you have a different opinion, how should we do a typechecking here? Is the following what you expected?
#define clamp_t(type, val, lo, hi) \
({ type _val = (val); \
type _lo = (lo); \
type _hi = (hi); \
min_t(type, max_t(type, _val, _lo), _hi)
})
Best,
Wei
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v4 02/11] x86/intel_pstate: add some calculation related support
2015-07-27 5:48 ` Wang, Wei W
@ 2015-08-11 10:07 ` Jan Beulich
0 siblings, 0 replies; 5+ messages in thread
From: Jan Beulich @ 2015-08-11 10:07 UTC (permalink / raw)
To: Wei W Wang; +Cc: andrew.cooper3, xen-devel
>>> On 27.07.15 at 07:48, <wei.w.wang@intel.com> wrote:
>> > +/*
>> > + * clamp_t - return a value clamped to a given range using a given
>> > +type
>> > + * @type: the type of variable to use
>> > + * @val: current value
>> > + * @lo: minimum allowable value
>> > + * @hi: maximum allowable value
>> > + *
>> > + * This macro does no typechecking and uses temporary variables of
>> > +type
>> > + * 'type' to make all the comparisons.
>> > + */
>> > +#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo),
>> > +hi)
>>
>> Shouldn't you also add a type checking variant then (which ought to be used
>> instead of the one above wherever possible)?
>
> Hi Jan, I think the max_t() and min_t() have handled the typechecking thing,
> maybe we do not need to do it again here.
> If you have a different opinion, how should we do a typechecking here? Is
> the following what you expected?
> #define clamp_t(type, val, lo, hi) \
> ({ type _val = (val); \
> type _lo = (lo); \
> type _hi = (hi); \
> min_t(type, max_t(type, _val, _lo), _hi)
> })
I don't think you understood: I asked for a clamp() to accompany
clamp_t(), just like e.g. max_t() is a less preferred sibling of max().
Jan
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v4 02/11] x86/intel_pstate: add some calculation related support
2015-06-25 11:14 [PATCH v4 02/11] x86/intel_pstate: add some calculation related support Wei Wang
2015-07-24 13:16 ` Jan Beulich
@ 2015-07-24 13:17 ` Jan Beulich
1 sibling, 0 replies; 5+ messages in thread
From: Jan Beulich @ 2015-07-24 13:17 UTC (permalink / raw)
To: Wei Wang; +Cc: andrew.cooper3, xen-devel
>>> On 25.06.15 at 13:14, <wei.w.wang@intel.com> wrote:
> The added calculation related functions will be used in the intel_pstate.c.
> They are copied from the Linux kernel(commit 2418f4f2, f3002134, eb18cba7).
>
> v4 changes:
> 1) in commit message, "kernel" changed to "Linux kernel"
> 2) if-else coding style change.
Oh, also - the change info belongs after the first --- separator.
Jan
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-06-25 11:14 [PATCH v4 02/11] x86/intel_pstate: add some calculation related support Wei Wang
2015-07-24 13:16 ` Jan Beulich
2015-07-27 5:48 ` Wang, Wei W
2015-08-11 10:07 ` Jan Beulich
2015-07-24 13:17 ` Jan Beulich
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