Re: [PATCH] x86: Add a turbo mode sysctl
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From: Thomas Gleixner <hidden>
Date: 2016-04-01 16:11:41
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On Fri, 1 Apr 2016, Andy Lutomirski wrote:
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+static void update_local_turbo_mode(void *dummy) +{ + unsigned long cr0 = read_cr0(); + + /* + * KVM doesn't properly handle CD. + * + * XXX: this may interact poorly with CPU hotplug.
Please cc these crazy folks who cleanup the hotplug mess so they can put it on their todo list.
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+ */ + + if (turbo_mode) + write_cr0(cr0 & ~X86_CR0_CD); + else + write_cr0(cr0 | X86_CR0_CD);
I think proper turbo mode disable requires ~(X86_CR0_CD | X86_CR0_NW)
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+static void update_turbo_mode(void) +{ + on_each_cpu(update_local_turbo_mode, NULL, 1); + + if (!turbo_mode) + wbinvd();
You really want to do wbinvd() on each cpu to make sure that each cpu gets out of that turbo thing. Thanks, tglx