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Re: [Qemu-devel] [PATCH v7 7/9] qemu/units: add SI decimal units
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v7 7/9] qemu/units: add SI decimal units |
Date: |
Fri, 9 Aug 2019 10:39:06 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
On 6/18/19 6:43 AM, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> include/qemu/units.h | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/include/qemu/units.h b/include/qemu/units.h
> index 692db3fbb2..52ccc7445c 100644
> --- a/include/qemu/units.h
> +++ b/include/qemu/units.h
> @@ -17,4 +17,11 @@
> #define PiB (INT64_C(1) << 50)
> #define EiB (INT64_C(1) << 60)
>
> +#define SI_k 1000LL
> +#define SI_M 1000000LL
> +#define SI_G 1000000000LL
> +#define SI_T 1000000000000LL
> +#define SI_P 1000000000000000LL
> +#define SI_E 1000000000000000000LL
Looks correct; and it's the sort of thing that if we do once here, we
don't have to repeat elsewhere. But bike-shedding a bit, would it be any
easier to read as:
#define SI_k 1000LL
#define SI_M (1000LL * 1000)
#define SI_G (1000LL * 1000 * 1000)
...
or even:
#define SI_k 1000LL
#define SI_M (SI_k * 1000)
#define SI_G (SI_M * 1000)
...
Also, would it be worth swapping out existing constants in the code base
that should instead be using these macros, so that they actually have a
use and so that we can see whether using them adds legibility?
For example, block/nvme.c, block/qapi.c, block/sheepdog.c, blockdev.c,
util/async.c, util/oslib-win32.c, util/qemu-thread-posix.c,
util/qemu-timer.c all seem to be dealing with conversions between
seconds and subdivisions thereof, where constants 1000000 or larger are
in use and could be rewritten with these.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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Eric Blake <=