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Date: Tue, 25 Oct 2011 11:30:21 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Avi Kivity <avi@redhat.com>
CC: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        Greg Kroah-Hartman <gregkh@suse.de>, KVM <kvm@vger.kernel.org>,
        Sedat Dilek <sedat.dilek@gmail.com>, Ingo Molnar <mingo@redhat.com>,
        Virtualization <virtualization@lists.linux-foundation.org>,
        "x86@kernel.org" <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
        Gleb Natapov <gleb@redhat.com>, Yinghai Lu <yinghai@kernel.org>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Xen <xen-devel@lists.xensource.com>, Rik van Riel <riel@redhat.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Suzuki Poulose <suzuki@linux.vnet.ibm.com>,
        Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH RFC V2 4/5] kvm guest : Added configuration support to
 enable debug information for KVM Guests
References: <20111023190307.16364.35381.sendpatchset@oc5400248562.ibm.com> <20111023190700.16364.7548.sendpatchset@oc5400248562.ibm.com> <4EA53AB2.9050805@redhat.com>
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On 10/24/2011 03:15 AM, Avi Kivity wrote:
> On 10/23/2011 09:07 PM, Raghavendra K T wrote:
>> Added configuration support to enable debug information
>> for KVM Guests in debugfs
>>     
>> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
>> Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com>
>> Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
>> ---
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 1f03f82..ed34269 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -562,6 +562,15 @@ config KVM_GUEST
>>  	  This option enables various optimizations for running under the KVM
>>  	  hypervisor.
>>  
>> +config KVM_DEBUG_FS
>> +	bool "Enable debug information for KVM Guests in debugfs"
>> +	depends on KVM_GUEST
>> +	default n
>> +	---help---
>> +	  This option enables collection of various statistics for KVM guest.
>> +   	  Statistics are displayed in debugfs filesystem. Enabling this option
>> +	  may incur significant overhead.
>> +
>>  source "arch/x86/lguest/Kconfig"
>>  
>>
> This might be better implemented through tracepoints, which an be
> enabled dynamically.

Tracepoints use spinlocks, so that could get awkward.

    J