Date: Fri, 11 Jun 2010 13:04:49 -0400 From: John Baldwin <jhb@freebsd.org> To: src-committers@freebsd.org Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org Subject: Re: svn commit: r209050 - head/sys/sys Message-ID: <201006111304.49966.jhb@freebsd.org> In-Reply-To: <201006111556.o5BFuIEi020826@svn.freebsd.org> References: <201006111556.o5BFuIEi020826@svn.freebsd.org>
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On Friday 11 June 2010 11:56:18 am John Baldwin wrote: > Author: jhb > Date: Fri Jun 11 15:56:18 2010 > New Revision: 209050 > URL: http://svn.freebsd.org/changeset/base/209050 > > Log: > Add helper macros to iterate over available CPUs in the system. > CPU_FOREACH(i) iterates over the CPU IDs of all available CPUs. The > CPU_FIRST() and CPU_NEXT(i) macros can also be used to iterate over > available CPU IDs. CPU_NEXT(i) wraps around to CPU_FIRST() rather than > returning some sort of terminator. The intended use case for CPU_FIRST() and CPU_NEXT() is to use it to do things like this: u_int hash[64]; int i, j; j = CPU_FIRST(); for (i = 0; i < 64; i++) { hash[i] = j; j = CPU_NEXT(j); } If the auto-wrapping semantics of CPU_NEXT() is too odd, we could make it return NOCPU when it hits the end of the list instead perhaps and use some other macro to provide the current CPU_NEXT()-like behavior. -- John Baldwin
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