From: Paolo Bonzini <pbonzini@redhat.com>
To: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: armbru@redhat.com, quintela@redhat.com,
Avi Kivity <avi@redhat.com>,
qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [PATCH 2/5] Support human unit formats in strtobytes, eg. 1.0G
Date: Thu, 16 Sep 2010 13:09:33 +0200 [thread overview]
Message-ID: <4C91FAED.5000903@redhat.com> (raw)
In-Reply-To: <4C91F47F.6020800@redhat.com>
On 09/16/2010 12:42 PM, Jes Sorensen wrote:
> On 09/16/10 12:40, Avi Kivity wrote:
>> On 09/15/2010 09:31 PM, Jes Sorensen wrote:
>>> Floating point is just plain wrong.
>>
>> Why? If command-line processing becomes too slow, you can always buy a
>> math co-processor.
>
> Because it's imprecise anyway
As Avi mentioned, this is only true if you need byte precision beyond 4
PB. But most of the time byte precision is not necessary so in practice
floating-point will be indistinguishable: all exact powers of 10 up to
10^22 (beyond 64-bits) can be represented correctly by an IEEE double.
There's also strtold, if you're worried about precision...
> Besides, most users will probably hit their shell command line limit
> before hitting the problem with the decimals.
Value is first shifted and then multiplied, so that 6-7 digits may
already overflow if the unit is terabytes.
Paolo
next prev parent reply other threads:[~2010-09-16 11:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-15 12:23 [Qemu-devel] [PATCH 0/5] Introduce strtobytes and make use of it Jes.Sorensen
2010-09-15 12:23 ` [Qemu-devel] [PATCH 1/5] Introduce strtobytes() library function to convert string to byte count Jes.Sorensen
2010-09-15 18:46 ` Andreas Färber
2010-09-15 20:50 ` Stefan Weil
2010-09-15 12:23 ` [Qemu-devel] [PATCH 2/5] Support human unit formats in strtobytes, eg. 1.0G Jes.Sorensen
2010-09-15 14:50 ` [Qemu-devel] " Juan Quintela
2010-09-15 19:29 ` Jes Sorensen
2010-09-15 15:45 ` Paolo Bonzini
2010-09-15 15:50 ` Anthony Liguori
2010-09-15 19:31 ` Jes Sorensen
2010-09-16 7:19 ` Paolo Bonzini
2010-09-16 10:14 ` Jes Sorensen
2010-09-16 10:40 ` Avi Kivity
2010-09-16 10:42 ` Jes Sorensen
2010-09-16 10:46 ` Avi Kivity
2010-09-16 11:09 ` Paolo Bonzini [this message]
2010-09-15 12:23 ` [Qemu-devel] [PATCH 3/5] Add support for 'o' octet (bytes) format as monitor parameter Jes.Sorensen
2010-09-15 12:23 ` [Qemu-devel] [PATCH 4/5] Switch migrate_set_speed() to take an 'o' argument rather than a float Jes.Sorensen
2010-09-15 12:24 ` [Qemu-devel] [PATCH 5/5] Remove obsolete 'f' double parameter type Jes.Sorensen
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