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Re: [PATCH v4 6/6] qht: Fix threshold rate calculation
From: |
Peter Maydell |
Subject: |
Re: [PATCH v4 6/6] qht: Fix threshold rate calculation |
Date: |
Fri, 19 Jun 2020 18:31:03 +0100 |
On Wed, 17 Jun 2020 at 21:59, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 6/17/20 1:13 PM, Richard Henderson wrote:
> > - *threshold = rate * UINT64_MAX;
> > + *threshold = (rate * 0xffff000000000000ull)
> > + + (rate * 0x0000ffffffffffffull);
>
> Well, while this does silence the warning, it produces the exact same results
> as before, since the intermediate double result still only has 53 bits of
> precision.
>
> We're probably be better off with the nextafter(0x1p64, 0.0) form that we've
> used elsewhere.
Yeah, the code does look a bit odd. I'm going to apply this one to master
as well just to suppress all the patchew nagmails, but we should
figure out the correct thing to do here.
thanks
-- PMM
- [PATCH v4 0/6] Vs clang-10 and gcc-9 warnings, Richard Henderson, 2020/06/17
- [PATCH v4 1/6] fpu/softfloat: Silence 'bitwise negation of boolean expression' warning, Richard Henderson, 2020/06/17
- [PATCH v4 2/6] migration: fix xbzrle encoding rate calculation, Richard Henderson, 2020/06/17
- [PATCH v4 3/6] configure: Clean up warning flag lists, Richard Henderson, 2020/06/17
- [PATCH v4 4/6] configure: Disable -Wtautological-type-limit-compare, Richard Henderson, 2020/06/17
- [PATCH v4 5/6] configure: Add -Wno-psabi, Richard Henderson, 2020/06/17
- [PATCH v4 6/6] qht: Fix threshold rate calculation, Richard Henderson, 2020/06/17
- Re: [PATCH v4 0/6] Vs clang-10 and gcc-9 warnings, Peter Maydell, 2020/06/18