Re: [PATCH 2/3] context_tracking: avoid irq_save/irq_restore on guest entry and exit
On 10/27/2015 09:39 PM, Paolo Bonzini wrote: > guest_enter and guest_exit must be called with interrupts disabled, > since they take the vtime_seqlock with write_seq{lock,unlock}. > Therefore, it is not necessary to check for exceptions, nor to > save/restore the IRQ state, when context tracking functions are > called by guest_enter and guest_exit. > > Split the body of context_tracking_entry and context_tracking_exit > out to __-prefixed functions, and use them from KVM. > > Rik van Riel has measured this to speed up a tight vmentry/vmexit > loop by about 2%. > > Cc: Andy Lutomirski > Cc: Frederic Weisbecker > Cc: Rik van Riel > Cc: Paul McKenney > Signed-off-by: Paolo Bonzini Reviewed-by: Rik van Riel Tested-by: Rik van Riel -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 2/3] context_tracking: avoid irq_save/irq_restore on guest entry and exit
On Tue, Oct 27, 2015 at 6:39 PM, Paolo Bonzini wrote: > guest_enter and guest_exit must be called with interrupts disabled, > since they take the vtime_seqlock with write_seq{lock,unlock}. > Therefore, it is not necessary to check for exceptions, nor to > save/restore the IRQ state, when context tracking functions are > called by guest_enter and guest_exit. > > Split the body of context_tracking_entry and context_tracking_exit > out to __-prefixed functions, and use them from KVM. > > Rik van Riel has measured this to speed up a tight vmentry/vmexit > loop by about 2%. Looks generally sensible. I'm not familiar enough with the code to call it reviewed-by while sitting on the airport shuttle. --Andy -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html