Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1238381

Re: [PATCH v3 2/9] xen-block: add document for mutli hardware queues/rings

Show all headers | View raw

El 05/09/15 a les 14.39, Bob Liu ha escrit:
> Document multi queues/rings of xen-block.
> 
> Signed-off-by: Bob Liu <bob.liu@oracle.com>

As said by Konrad, you should send this against the Xen public headers
also (or even before). I have a comment below.

> ---
>  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>"

AFAICT, it's impossible by design to use multiple queues together with
multipage rings, is that right?

Roger.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH v3 2/9] xen-block: add document for mutli hardware  queues/rings Roger Pau Monné <roger.pau@citrix.com> - 2015-10-02 18:10 +0200
  Re: [Xen-devel] [PATCH v3 2/9] xen-block: add document for mutli  hardware queues/rings Wei Liu <wei.liu2@citrix.com> - 2015-10-02 18:20 +0200
    Re: [Xen-devel] [PATCH v3 2/9] xen-block: add document for mutli  hardware queues/rings Roger Pau Monné <roger.pau@citrix.com> - 2015-10-02 18:30 +0200
      Re: [Xen-devel] [PATCH v3 2/9] xen-block: add document for mutli  hardware queues/rings Bob Liu <bob.liu@oracle.com> - 2015-10-03 02:00 +0200

csiph-web