svn commit: r209119 - head/sys/sys
Lawrence Stewart
lstewart at freebsd.org
Sun Jun 13 13:41:41 UTC 2010
On 06/13/10 20:10, Pawel Jakub Dawidek wrote:
> On Sun, Jun 13, 2010 at 02:39:55AM +0000, Lawrence Stewart wrote:
>> Author: lstewart
>> Date: Sun Jun 13 02:39:55 2010
>> New Revision: 209119
>> URL: http://svn.freebsd.org/changeset/base/209119
>>
>> Log:
>> Add a utility macro to simplify calculating an aggregate sum from a DPCPU
>> counter variable.
>>
>> Sponsored by: FreeBSD Foundation
>> Reviewed by: jhb, rpaulo, rwatson (previous version of patch)
>> MFC after: 1 week
>>
>> Modified:
>> head/sys/sys/pcpu.h
>>
>> Modified: head/sys/sys/pcpu.h
>> ==============================================================================
>> --- head/sys/sys/pcpu.h Sun Jun 13 01:27:29 2010 (r209118)
>> +++ head/sys/sys/pcpu.h Sun Jun 13 02:39:55 2010 (r209119)
>> @@ -106,6 +106,17 @@ extern uintptr_t dpcpu_off[];
>> #define DPCPU_ID_GET(i, n) (*DPCPU_ID_PTR(i, n))
>> #define DPCPU_ID_SET(i, n, v) (*DPCPU_ID_PTR(i, n) = v)
>>
>> +/*
>> + * Utility macros.
>> + */
>> +#define DPCPU_SUM(n, var, sum) \
>> +do { \
>> + (sum) = 0; \
>> + u_int i; \
>> + CPU_FOREACH(i) \
>> + (sum) += (DPCPU_ID_PTR(i, n))->var; \
>> +} while (0)
>
> I'd suggest first swapping variable declaration and '(sum) = 0;'.
Can do (will wait until consensus on other issues is reached first
before tweaking though).
> Also using 'i' as a counter in macro can easly lead to name collision.
I had a similar concern but after chatting with John on IRC felt it
wasn't such a big deal in this case.
> If you need to do it, I'd suggest '_i' or something.
Could do... is it worth it?
> Maybe it would be better to make it an inline function rather than macro?
Inlining it could be annoying with respect to the types used in the
function prototype, no? I suspect it would be more useful keeping it as
a macro if possible.
Cheers,
Lawrence
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