[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 2/9] xen-block: add document for mutli hardware queues/rings
On Sat, Sep 05, 2015 at 08:39:35PM +0800, Bob Liu wrote: > Document multi queues/rings of xen-block. This needs to be posted on Xen devel as well so that the blkif.h header in Xen has this. > > Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx> > --- > include/xen/interface/io/blkif.h | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/include/xen/interface/io/blkif.h > b/include/xen/interface/io/blkif.h > index c33e1c4..b453b70 100644 > --- a/include/xen/interface/io/blkif.h > +++ b/include/xen/interface/io/blkif.h > @@ -28,6 +28,38 @@ typedef uint16_t blkif_vdev_t; > typedef uint64_t blkif_sector_t; > > /* > + * Multiple hardware queues/rings: > + * If supported, the backend will write the key "multi-queue-max-queues" to > + * the directory for that vbd, and set its value to the maximum supported > + * number of queues. > + * Frontends that are aware of this feature and wish to use it can write the > + * key "multi-queue-num-queues", set to the number they wish to use, which > + * must be greater than zero, and no more than the value reported by the > backend > + * in "multi-queue-max-queues". > + * > + * For frontends requesting just one queue, the usual event-channel and > + * ring-ref keys are written as before, simplifying the backend processing > + * to avoid distinguishing between a frontend that doesn't understand the > + * multi-queue feature, and one that does, but requested only one queue. > + * > + * Frontends requesting two or more queues must not write the toplevel > + * event-channeland ring-ref keys, instead writing those keys under sub-keys > + * having the name "queue-N" where N is the integer ID of the queue/ring for > + * which those keys belong. Queues are indexed from zero. > + * For example, a frontend with two queues must write the following set of > + * queue-related keys: > + * > + * /local/domain/1/device/vbd/0/multi-queue-num-queues = "2" > + * /local/domain/1/device/vbd/0/queue-0 = "" > + * /local/domain/1/device/vbd/0/queue-0/ring-ref = "<ring-ref>" > + * /local/domain/1/device/vbd/0/queue-0/event-channel = "<evtchn>" > + * /local/domain/1/device/vbd/0/queue-1 = "" > + * /local/domain/1/device/vbd/0/queue-1/ring-ref = "<ring-ref>" > + * /local/domain/1/device/vbd/0/queue-1/event-channel = "<evtchn>" > + * > + */ > + > +/* > * REQUEST CODES. > */ > #define BLKIF_OP_READ 0 > -- > 1.7.10.4 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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