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Tsirkin wrote: > On Mon, Mar 14, 2022 at 12:25:08PM +0200, Max Gurtovoy wrote: >> On 3/14/2022 11:43 AM, Suwan Kim wrote: >>> On Sun, Mar 13, 2022 at 12:37:21PM +0200, Max Gurtovoy wrote: >>>> On 3/11/2022 6:07 PM, Suwan Kim wrote: >>>>> On Fri, Mar 11, 2022 at 10:38:07AM -0500, Michael S. Tsirkin wrote: >>>>>> On Sat, Mar 12, 2022 at 12:28:32AM +0900, Suwan Kim wrote: >>>>>>> diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h >>>>>>> index d888f013d9ff..3fcaf937afe1 100644 >>>>>>> --- a/include/uapi/linux/virtio_blk.h >>>>>>> +++ b/include/uapi/linux/virtio_blk.h >>>>>>> @@ -119,8 +119,9 @@ struct virtio_blk_config { >>>>>>> * deallocation of one or more of the sectors. >>>>>>> */ >>>>>>> __u8 write_zeroes_may_unmap; >>>>>>> + __u8 unused1; >>>>>>> - __u8 unused1[3]; >>>>>>> + __virtio16 num_poll_queues; >>>>>>> } __attribute__((packed)); >>>>>> Same as any virtio UAPI change, this has to go through the virtio TC. >>>>>> In particular I don't think gating a new config field on >>>>>> an existing feature flag is a good idea. >>>>> Did you mean that the polling should be based on a new feature like >>>>> "VIRTIO_BLK_F_POLL" and be added at the end of features_legacy[] >>>>> and features[]? If then, I will add the new feture flag and resend it. >>>> Isn't there a way in the SPEC today to create a queue without interrupt >>>> vector ? >>> It seems that it is not possible to create a queue without interrupt >>> vector. If it is possible, we can expect more polling improvement. > Yes, it's possible: > > Writing a valid MSI-X Table entry number, 0 to 0x7FF, to > \field{config_msix_vector}/\field{queue_msix_vector} maps interrupts triggered > by the configuration change/selected queue events respectively to > the corresponding MSI-X vector. To disable interrupts for an > event type, the driver unmaps this event by writing a special NO_VECTOR > value: > > \begin{lstlisting} > /* Vector value used to disable MSI for queue */ > #define VIRTIO_MSI_NO_VECTOR 0xffff > \end{lstlisting} > > > >> MST/Jason/Stefan, >> >> can you confirm that please ? >> >> what does VIRTQ_AVAIL_F_NO_INTERRUPT supposed to do ? > This is a hint to the device not to send interrupts. Why do you need a hint if the driver implicitly wrote 0xffff to disable MSI for a virtqueue ? > >>> Regards, >>> Suwan Kim