On 02/19/2014 11:24 AM, Waiman Long wrote: > On 02/19/2014 03:51 AM, Peter Zijlstra wrote: >> On Tue, Feb 18, 2014 at 07:42:20PM -0500, Waiman Long wrote: >>> On 02/18/2014 04:28 PM, Peter Zijlstra wrote: >>>> On Tue, Feb 18, 2014 at 02:30:12PM -0500, Waiman Long wrote: >>>>> I will start looking at how to make it work with paravirt. >>>>> Hopefully, it >>>>> won't take too long. >>>> The cheap way out is to simply switch to the test-and-set spinlock on >>>> whatever X86_FEATURE_ indicates a guest I suppose. >>> I don't think there is X86_FEATURE flag that indicates running in a >>> guest. >>> In fact, a guest should never find out if it is running virtualized. >> No it very much should; how else is paravirt ever going to work? > > We do have a CONFIG_PARAVIRT macro that turns on or off PV support. The > queue spinlock can be easily changed into an unfair lock which allows > lock stealing. We could have a config option to make it unfair in the > PARAVIRT environment, but I don't think Linus like the idea of an unfair > lock. > The case where we run native on a system with CONFIG_PARAVIRT enabled DOES matter. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
