Messages in this thread | | | Date | Tue, 23 Mar 2010 15:47:57 +0100 | From | Dominik Brodowski <> | Subject | Re: [PATCH 2/5] powernow-k8: Add core performance boost support |
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Hey Borislav,
On Tue, Mar 23, 2010 at 03:19:34PM +0100, Borislav Petkov wrote: > From: Dominik Brodowski <linux@dominikbrodowski.net> > Date: Tue, Mar 23, 2010 at 02:27:37PM +0100 > > Hi Dominik, > > > On Tue, Mar 23, 2010 at 12:58:58PM +0100, Borislav Petkov wrote: > > > > It could already be set in arch/x86/kernel/cpu/amd.c and > > > > powernow-k8 could use cpu_has(cpu, X86_FEATURE_CPB); > > > > > > I'd still like to cache the cpb_capable value locally instead of getting > > > x86_cpuinfo percpu var and querying it. Especially if this happens often > > > and not only at driver init. > > > > If it's a percpu var, isn't it local anyway? > > I meant driver-local. So that I don't have to deref even the per_cpu var > and thus save some cycles.
Well, it doesn't seem to be used in any hot path (and if it were, using a per-cpu var was better anyway, because of no contention etc.). If it really saves some cycles, I'm more than fine with keeping it; still, informing the user in /proc/cpuinfo seems like a sensible thing to do.
Best, Dominik
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