Date: Mon, 5 Aug 2002 01:53:40 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Terry Lambert <tlambert2@mindspring.com> Cc: smp@freebsd.org Subject: Re: how to create per-cpu variables in SMP kernels ? Message-ID: <20020805015340.A17716@iguana.icir.org> In-Reply-To: <3D4E1ECB.348978D1@mindspring.com>; from tlambert2@mindspring.com on Sun, Aug 04, 2002 at 11:44:27PM -0700 References: <20020804182713.A14944@iguana.icir.org> <3D4E1ECB.348978D1@mindspring.com>
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On Sun, Aug 04, 2002 at 11:44:27PM -0700, Terry Lambert wrote: > > I would like to know how does the FreeBSD kernel (both in -current > > and -stable) handle per-cpu variables such as curproc/curthread, cpuid, ... > > How expensive is to access them compared to regular variables ? > > Depends on the specific variable's implementation. If you are asking > because you want to add one, then don't. 8-). They damage symmetry i am asking because in the code I see several instance of things like p = curproc; <code using p instead of curproc> in a context where curproc is not supposed to change. Is there a performance bonus in doing this, or not ? cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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