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Re: [Qemu-devel] [PATCH v2 1/3] throttle: Make NANOSECONDS_PER_SECOND an
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/3] throttle: Make NANOSECONDS_PER_SECOND an integer |
Date: |
Mon, 08 Sep 2014 08:46:05 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 |
On 09/08/2014 06:18 AM, Benoît Canet wrote:
> We will want to reuse this define in the future by making it common to
> multiples
s/multiples/multiple/
> QEMU modules.
> It would be safer that this define be an integer so we avoid stranges float
s/stranges/strange/
> rounding errors.
> Do this conversion.
>
> Signed-off-by: Benoît Canet <address@hidden>
> ---
> include/qemu/throttle.h | 2 +-
> util/throttle.c | 4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/qemu/throttle.h b/include/qemu/throttle.h
> index b890613..8f9e611 100644
> --- a/include/qemu/throttle.h
> +++ b/include/qemu/throttle.h
> @@ -27,7 +27,7 @@
> #include "qemu-common.h"
> #include "qemu/timer.h"
>
> -#define NANOSECONDS_PER_SECOND 1000000000.0
> +#define NANOSECONDS_PER_SECOND 1000000000
This hunk is good.
>
> typedef enum {
> THROTTLE_BPS_TOTAL,
> diff --git a/util/throttle.c b/util/throttle.c
> index f976ac7..af8445a 100644
> --- a/util/throttle.c
> +++ b/util/throttle.c
> @@ -34,7 +34,7 @@ void throttle_leak_bucket(LeakyBucket *bkt, int64_t
> delta_ns)
> double leak;
>
> /* compute how much to leak */
> - leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
> + leak = (bkt->avg * (double) delta_ns) / (double) NANOSECONDS_PER_SECOND;
This hunk is spurious. With just your first hunk, it evaluates to the
following types via promotion rules:
(double * double) / int
double / int
double / double
double
so the explicit cast isn't changing anything.
>
> /* make the bucket leak */
> bkt->level = MAX(bkt->level - leak, 0);
> @@ -70,7 +70,7 @@ static void throttle_do_leak(ThrottleState *ts, int64_t now)
> */
> static int64_t throttle_do_compute_wait(double limit, double extra)
> {
> - double wait = extra * NANOSECONDS_PER_SECOND;
> + double wait = extra * (double) NANOSECONDS_PER_SECOND;
This hunk is also spurious. Again, with just your first hunk, it
evaluates through the following promotion rules:
double * int
double * double
double
and the cast isn't changing anything.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, (continued)
- [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Benoît Canet, 2014/09/08
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Paolo Bonzini, 2014/09/08
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Benoît Canet, 2014/09/08
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Paolo Bonzini, 2014/09/08
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Benoît Canet, 2014/09/08
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Markus Armbruster, 2014/09/15
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Benoît Canet, 2014/09/15
- Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Benoît Canet, 2014/09/15
Re: [Qemu-devel] [PATCH v2 3/3] util: Add an utility infrastructure used to compute an average on a time slice, Markus Armbruster, 2014/09/15
[Qemu-devel] [PATCH v2 1/3] throttle: Make NANOSECONDS_PER_SECOND an integer, Benoît Canet, 2014/09/08