From: "Michael S. Tsirkin" <mst@redhat.com> To: linux-kernel@vger.kernel.org Cc: Rusty Russell <rusty@rustcorp.com.au>, Carsten Otte <cotte@de.ibm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, linux390@de.ibm.com, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Shirley Ma <xma@us.ibm.com>, lguest@lists.ozlabs.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, Krishna Kumar <krkumar2@in.ibm.com>, Tom Lendacky <tahm@linux.vnet.ibm.com>, steved@us.ibm.com, habanero@linux.vnet.ibm.com Subject: [PATCHv2 02/14] virtio ring: inline function to check for events Date: Fri, 20 May 2011 02:10:27 +0300 [thread overview] Message-ID: <16ce853af7a80d0f7cb0c1118ba8e19adc184ad0.1305846412.git.mst@redhat.com> (raw) In-Reply-To: <cover.1305846412.git.mst@redhat.com> With the new used_event and avail_event and features, both host and guest need similar logic to check whether events are enabled, so it helps to put the common code in the header. Note that Xen has similar logic for notification hold-off in include/xen/interface/io/ring.h with req_event and req_prod corresponding to event_idx + 1 and new_idx respectively. +1 comes from the fact that req_event and req_prod in Xen start at 1, while event index in virtio starts at 0. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- include/linux/virtio_ring.h | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 70b0b39..cf020e3 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -123,6 +123,20 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; } +/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ +/* Assuming a given event_idx value from the other size, if + * we have just incremented index from old to new_idx, + * should we trigger an event? */ +static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) +{ + /* Note: Xen has similar logic for notification hold-off + * in include/xen/interface/io/ring.h with req_event and req_prod + * corresponding to event_idx + 1 and new_idx respectively. + * Note also that req_event and req_prod in Xen start at 1, + * event indexes in virtio start at 0. */ + return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old); +} + #ifdef __KERNEL__ #include <linux/irqreturn.h> struct virtio_device; -- 1.7.5.53.gc233e
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Krishna Kumar <krkumar2-xthvdsQ13ZrQT0dZR+AlfA@public.gmane.org>, Carsten Otte <cotte-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, lguest-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Shirley Ma <xma-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, habanero-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, Heiko Carstens <heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, steved-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org, Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, Tom Lendacky <tahm-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Martin Schwidefsky <schwidefsky-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>, linux390-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Subject: [PATCHv2 02/14] virtio ring: inline function to check for events Date: Fri, 20 May 2011 02:10:27 +0300 [thread overview] Message-ID: <16ce853af7a80d0f7cb0c1118ba8e19adc184ad0.1305846412.git.mst@redhat.com> (raw) In-Reply-To: <cover.1305846412.git.mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> With the new used_event and avail_event and features, both host and guest need similar logic to check whether events are enabled, so it helps to put the common code in the header. Note that Xen has similar logic for notification hold-off in include/xen/interface/io/ring.h with req_event and req_prod corresponding to event_idx + 1 and new_idx respectively. +1 comes from the fact that req_event and req_prod in Xen start at 1, while event index in virtio starts at 0. Signed-off-by: Michael S. Tsirkin <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> --- include/linux/virtio_ring.h | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 70b0b39..cf020e3 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -123,6 +123,20 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; } +/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ +/* Assuming a given event_idx value from the other size, if + * we have just incremented index from old to new_idx, + * should we trigger an event? */ +static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) +{ + /* Note: Xen has similar logic for notification hold-off + * in include/xen/interface/io/ring.h with req_event and req_prod + * corresponding to event_idx + 1 and new_idx respectively. + * Note also that req_event and req_prod in Xen start at 1, + * event indexes in virtio start at 0. */ + return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old); +} + #ifdef __KERNEL__ #include <linux/irqreturn.h> struct virtio_device; -- 1.7.5.53.gc233e
next prev parent reply other threads:[~2011-05-19 23:11 UTC|newest] Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-05-19 23:10 [PATCHv2 00/14] virtio and vhost-net performance enhancements Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-19 23:10 ` [PATCHv2 01/14] virtio: event index interface Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-21 2:29 ` Rusty Russell 2011-05-21 2:29 ` Rusty Russell 2011-05-21 2:29 ` Rusty Russell 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin [this message] 2011-05-19 23:10 ` [PATCHv2 02/14] virtio ring: inline function to check for events Michael S. Tsirkin 2011-05-21 2:29 ` Rusty Russell 2011-05-21 2:29 ` Rusty Russell 2011-05-21 2:29 ` Rusty Russell 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-19 23:10 ` [PATCHv2 03/14] virtio_ring: support event idx feature Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-21 2:31 ` Rusty Russell 2011-05-21 2:31 ` Rusty Russell 2011-05-21 2:31 ` Rusty Russell 2011-05-19 23:10 ` [PATCHv2 04/14] vhost: support event index Michael S. Tsirkin 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-21 2:31 ` Rusty Russell 2011-05-21 2:31 ` Rusty Russell 2011-05-21 2:31 ` Rusty Russell 2011-05-19 23:10 ` Michael S. Tsirkin 2011-05-19 23:11 ` [PATCHv2 05/14] virtio_test: " Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-21 2:32 ` Rusty Russell 2011-05-21 2:32 ` Rusty Russell 2011-05-21 2:32 ` Rusty Russell 2011-05-19 23:11 ` [PATCHv2 06/14] virtio: add api for delayed callbacks Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-21 2:33 ` Rusty Russell 2011-05-21 2:33 ` Rusty Russell 2011-05-21 2:33 ` Rusty Russell 2011-05-19 23:11 ` [PATCHv2 07/14] virtio_net: delay TX callbacks Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` [PATCHv2 08/14] virtio_ring: Add capacity check API Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` [PATCHv2 09/14] virtio_net: fix TX capacity checks using new API Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-21 2:13 ` Rusty Russell 2011-05-21 2:13 ` Rusty Russell 2011-05-21 2:13 ` Rusty Russell 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:11 ` [PATCHv2 10/14] virtio_net: limit xmit polling Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-21 2:19 ` Rusty Russell 2011-05-21 2:19 ` Rusty Russell 2011-05-21 2:19 ` Rusty Russell 2011-05-22 12:10 ` Michael S. Tsirkin 2011-05-22 12:10 ` Michael S. Tsirkin 2011-05-23 2:07 ` Rusty Russell 2011-05-23 2:07 ` Rusty Russell 2011-05-23 11:19 ` Michael S. Tsirkin 2011-05-23 11:19 ` Michael S. Tsirkin 2011-05-23 11:19 ` Michael S. Tsirkin 2011-05-24 7:54 ` Krishna Kumar2 2011-05-24 7:54 ` Krishna Kumar2 2011-05-24 9:12 ` Michael S. Tsirkin 2011-05-24 9:12 ` Michael S. Tsirkin 2011-05-24 9:12 ` Michael S. Tsirkin 2011-05-24 9:27 ` Krishna Kumar2 2011-05-24 9:27 ` Krishna Kumar2 2011-05-24 11:29 ` Michael S. Tsirkin 2011-05-24 11:29 ` Michael S. Tsirkin 2011-05-24 12:50 ` Krishna Kumar2 2011-05-24 12:50 ` Krishna Kumar2 2011-05-24 13:52 ` Michael S. Tsirkin 2011-05-24 13:52 ` Michael S. Tsirkin 2011-05-24 13:52 ` Michael S. Tsirkin 2011-05-24 12:50 ` Krishna Kumar2 2011-05-24 11:29 ` Michael S. Tsirkin 2011-05-24 7:54 ` Krishna Kumar2 2011-05-25 1:28 ` Rusty Russell 2011-05-25 1:28 ` Rusty Russell 2011-05-25 5:50 ` Michael S. Tsirkin 2011-05-25 5:50 ` Michael S. Tsirkin 2011-05-25 5:50 ` Michael S. Tsirkin 2011-05-25 1:28 ` Rusty Russell 2011-05-25 1:35 ` Rusty Russell 2011-05-25 1:35 ` Rusty Russell 2011-05-25 1:35 ` Rusty Russell 2011-05-25 6:07 ` Michael S. Tsirkin 2011-05-25 6:07 ` Michael S. Tsirkin 2011-05-26 3:28 ` Rusty Russell 2011-05-26 3:28 ` Rusty Russell 2011-05-26 3:28 ` Rusty Russell 2011-05-28 20:02 ` Michael S. Tsirkin 2011-05-28 20:02 ` Michael S. Tsirkin 2011-05-30 6:27 ` Rusty Russell 2011-05-30 6:27 ` Rusty Russell 2011-05-30 6:27 ` Rusty Russell 2011-05-28 20:02 ` Michael S. Tsirkin 2011-05-25 6:07 ` Michael S. Tsirkin 2011-05-23 2:07 ` Rusty Russell 2011-05-22 12:10 ` Michael S. Tsirkin 2011-05-19 23:11 ` Michael S. Tsirkin 2011-05-19 23:12 ` [PATCHv2 11/14] virtio: don't delay avail index update Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-21 2:26 ` Rusty Russell 2011-05-21 2:26 ` Rusty Russell 2011-05-21 2:26 ` Rusty Russell 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` [PATCHv2 12/14] virtio: 64 bit features Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` [PATCHv2 13/14] virtio_test: update for " Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` [PATCHv2 14/14] vhost: fix " Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:12 ` Michael S. Tsirkin 2011-05-19 23:20 ` [PATCHv2 00/14] virtio and vhost-net performance enhancements David Miller 2011-05-19 23:20 ` David Miller 2011-05-20 7:51 ` Rusty Russell 2011-05-20 7:51 ` Rusty Russell 2011-05-20 7:51 ` Rusty Russell 2011-05-26 15:32 ` [PERF RESULTS] " Krishna Kumar2 2011-05-26 15:32 ` Krishna Kumar2 2011-05-26 15:42 ` Shirley Ma 2011-05-26 16:21 ` Krishna Kumar2 2011-05-26 16:21 ` Krishna Kumar2 [not found] ` <OFF9D0E604.B865A006-ON6525789C.00597010-6525789C.0059987A@LocalDomain> 2011-05-26 16:29 ` Krishna Kumar2 2011-05-26 16:29 ` Krishna Kumar2 2011-05-26 16:29 ` Krishna Kumar2 2011-05-26 15:32 ` Krishna Kumar2
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