From: "Maciej Żenczykowski" <maze@google.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Brian Vazquez <brianvv@google.com>,
Brian Vazquez <brianvv.kernel@gmail.com>,
David Ahern <dsahern@gmail.com>,
Mahesh Bandewar <maheshb@google.com>,
Linux NetDev <netdev@vger.kernel.org>,
Leslie Monis <lesliemonis@gmail.com>
Subject: Re: [PATCH iproute2] tc: fix warning in q_pie.c
Date: Wed, 27 Nov 2019 08:44:46 -0800 [thread overview]
Message-ID: <CANP3RGctgy98FsyeHq+aVk2S=N8ndY0Y+qMkZUhTB=26H_Y3Rg@mail.gmail.com> (raw)
In-Reply-To: <20191127082655.2e914675@hermes.lan>
> What compiler is this?
> The type seems correct already. The type of double / unsigned long is double.
> And the conversion may give different answer.
Probably some recent version of clang with -Wall.
That said, I think the warning/error is correct.
UINT64 doesn't fit in double (which is also 64 bits, but includes sign
and exponent) - you lose ~13 bits of precision.
I'm not aware of a way to (natively) divide a double by a uint64
without the loss (not that it really matters since the double doesn't
have the requisite precision in the first place).
Why do you think the conversion will give a different answer?
Isn't this exactly what the compiler will do anyway?
It's not like we have long double anymore...
next prev parent reply other threads:[~2019-11-27 16:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 5:20 [PATCH iproute2] tc: fix warning in q_pie.c Brian Vazquez
2019-11-27 16:26 ` Stephen Hemminger
2019-11-27 16:44 ` Maciej Żenczykowski [this message]
2019-11-27 17:25 ` Brian Vazquez
2019-11-28 5:24 ` Leslie Monis
2019-12-04 19:37 ` Stephen Hemminger
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