Date: Mon, 14 Jun 2010 08:25:47 -0400 From: John Baldwin <jhb@freebsd.org> To: Lawrence Stewart <lstewart@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: svn commit: r209119 - head/sys/sys Message-ID: <201006140825.47375.jhb@freebsd.org> In-Reply-To: <4C14E012.7080902@freebsd.org> References: <201006130239.o5D2du3m086332@svn.freebsd.org> <20100613101025.GD1320@garage.freebsd.pl> <4C14E012.7080902@freebsd.org>
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On Sunday 13 June 2010 9:41:38 am Lawrence Stewart wrote: > 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. Actually, I am a fan of using an inline function if possible to avoid the name collisions. -- John Baldwin
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