Linux Virtualization - Jan 2017 - [virtio-dev] Re: [PATCH v6 kernel 2/5] virtio-balloon: define new feature bit and head struct

On Fri, Jan 13, 2017 at 09:24:22AM +0000, Li, Liang Z
wrote:
> > On Wed, Dec 21, 2016 at 02:52:25PM +0800, Liang Li wrote:
> > > Add a new feature which supports sending the page information
with
> > > range array. The current implementation uses PFNs array, which is
not
> > > very efficient. Using ranges can improve the performance of
> > > inflating/deflating significantly.
> > >
> > > Signed-off-by: Liang Li <liang.z.li at intel.com>
> > > Cc: Michael S. Tsirkin <mst at redhat.com>
> > > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > > Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> > > Cc: Amit Shah <amit.shah at redhat.com>
> > > Cc: Dave Hansen <dave.hansen at intel.com>
> > > Cc: Andrea Arcangeli <aarcange at redhat.com>
> > > Cc: David Hildenbrand <david at redhat.com>
> > > ---
> > >  include/uapi/linux/virtio_balloon.h | 12 ++++++++++++
> > >  1 file changed, 12 insertions(+)
> > >
> > > diff --git a/include/uapi/linux/virtio_balloon.h
> > > b/include/uapi/linux/virtio_balloon.h
> > > index 343d7dd..2f850bf 100644
> > > --- a/include/uapi/linux/virtio_balloon.h
> > > +++ b/include/uapi/linux/virtio_balloon.h
> > > @@ -34,10 +34,14 @@
> > >  #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before
> > reclaiming pages */
> > >  #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats virtqueue
> > */
> > >  #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate balloon
> > on OOM */
> > > +#define VIRTIO_BALLOON_F_PAGE_RANGE	3 /* Send page info
> > with ranges */
> > >
> > >  /* Size of a PFN in the balloon interface. */  #define
> > > VIRTIO_BALLOON_PFN_SHIFT 12
> > >
> > > +/* Bits width for the length of the pfn range */
> > 
> > What does this mean? Couldn't figure it out.
> > 
> > > +#define VIRTIO_BALLOON_NR_PFN_BITS 12
> > > +
> > >  struct virtio_balloon_config {
> > >  	/* Number of pages host wants Guest to give up. */
> > >  	__u32 num_pages;
> > > @@ -82,4 +86,12 @@ struct virtio_balloon_stat {
> > >  	__virtio64 val;
> > >  } __attribute__((packed));
> > >
> > > +/* Response header structure */
> > > +struct virtio_balloon_resp_hdr {
> > > +	__le64 cmd : 8; /* Distinguish different requests type */
> > > +	__le64 flag: 8; /* Mark status for a specific request type */
> > > +	__le64 id : 16; /* Distinguish requests of a specific type */
> > > +	__le64 data_len: 32; /* Length of the following data, in bytes
*/
> > 
> > This use of __le64 makes no sense.  Just use u8/le16/le32 pls.
> > 
> 
> Got it, will change in the next version. 
> 
> And could help take a look at other parts? as well as the QEMU part.
> 
> Thanks!
> Liang
Yes but first I would like to understand how come no fields
in this new structure come up if I search for them in the
following patch. I don't see why should I waste time on
reviewing the implementation if the interface isn't
reasonable. You don't have to waste it too - just send RFC
patches with the header until we can agree on it.

-- 
MST

> Sent: Wednesday, January 18, 2017 3:11 AM
> To: Li, Liang Z
> Cc: kvm at vger.kernel.org; virtio-dev at lists.oasis-open.org; qemu-
> devel at nongnu.org; linux-mm at kvack.org; linux-kernel at
vger.kernel.org;
> virtualization at lists.linux-foundation.org; amit.shah at redhat.com;
Hansen,
> Dave; cornelia.huck at de.ibm.com; pbonzini at redhat.com;
> david at redhat.com; aarcange at redhat.com; dgilbert at redhat.com;
> quintela at redhat.com
> Subject: Re: [virtio-dev] Re: [PATCH v6 kernel 2/5] virtio-balloon: define
new
> feature bit and head struct
> 
> On Fri, Jan 13, 2017 at 09:24:22AM +0000, Li, Liang Z wrote:
> > > On Wed, Dec 21, 2016 at 02:52:25PM +0800, Liang Li wrote:
> > > > Add a new feature which supports sending the page
information with
> > > > range array. The current implementation uses PFNs array,
which is
> > > > not very efficient. Using ranges can improve the performance
of
> > > > inflating/deflating significantly.
> > > >
> > > > Signed-off-by: Liang Li <liang.z.li at intel.com>
> > > > Cc: Michael S. Tsirkin <mst at redhat.com>
> > > > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > > > Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> > > > Cc: Amit Shah <amit.shah at redhat.com>
> > > > Cc: Dave Hansen <dave.hansen at intel.com>
> > > > Cc: Andrea Arcangeli <aarcange at redhat.com>
> > > > Cc: David Hildenbrand <david at redhat.com>
> > > > ---
> > > >  include/uapi/linux/virtio_balloon.h | 12 ++++++++++++
> > > >  1 file changed, 12 insertions(+)
> > > >
> > > > diff --git a/include/uapi/linux/virtio_balloon.h
> > > > b/include/uapi/linux/virtio_balloon.h
> > > > index 343d7dd..2f850bf 100644
> > > > --- a/include/uapi/linux/virtio_balloon.h
> > > > +++ b/include/uapi/linux/virtio_balloon.h
> > > > @@ -34,10 +34,14 @@
> > > >  #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell before
> > > reclaiming pages */
> > > >  #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats
virtqueue
> > > */
> > > >  #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate
> balloon
> > > on OOM */
> > > > +#define VIRTIO_BALLOON_F_PAGE_RANGE	3 /* Send page info
> > > with ranges */
> > > >
> > > >  /* Size of a PFN in the balloon interface. */  #define
> > > > VIRTIO_BALLOON_PFN_SHIFT 12
> > > >
> > > > +/* Bits width for the length of the pfn range */
> > >
> > > What does this mean? Couldn't figure it out.
> > >
> > > > +#define VIRTIO_BALLOON_NR_PFN_BITS 12
> > > > +
> > > >  struct virtio_balloon_config {
> > > >  	/* Number of pages host wants Guest to give up. */
> > > >  	__u32 num_pages;
> > > > @@ -82,4 +86,12 @@ struct virtio_balloon_stat {
> > > >  	__virtio64 val;
> > > >  } __attribute__((packed));
> > > >
> > > > +/* Response header structure */
> > > > +struct virtio_balloon_resp_hdr {
> > > > +	__le64 cmd : 8; /* Distinguish different requests type */
> > > > +	__le64 flag: 8; /* Mark status for a specific request type
*/
> > > > +	__le64 id : 16; /* Distinguish requests of a specific type
*/
> > > > +	__le64 data_len: 32; /* Length of the following data, in
bytes
> > > > +*/
> > >
> > > This use of __le64 makes no sense.  Just use u8/le16/le32 pls.
> > >
> >
> > Got it, will change in the next version.
> >
> > And could help take a look at other parts? as well as the QEMU part.
> >
> > Thanks!
> > Liang
> 
> Yes but first I would like to understand how come no fields in this new
> structure come up if I search for them in the following patch. I don't
see why
It's not true, all of the field will be referenced in the following patches
except
the 'reserved' filed.
> should I waste time on reviewing the implementation if the interface
isn't
> reasonable. You don't have to waste it too - just send RFC patches with
the
> header until we can agree on it.
OK. I will post the header part separately.

Thanks!
Liang
> 
> --
> MST
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: virtio-dev-unsubscribe at lists.oasis-open.org
> For additional commands, e-mail: virtio-dev-help at lists.oasis-open.org

On Wed, Jan 18, 2017 at 01:55:12AM +0000, Li, Liang Z
wrote:
> > Sent: Wednesday, January 18, 2017 3:11 AM
> > To: Li, Liang Z
> > Cc: kvm at vger.kernel.org; virtio-dev at lists.oasis-open.org; qemu-
> > devel at nongnu.org; linux-mm at kvack.org; linux-kernel at
vger.kernel.org;
> > virtualization at lists.linux-foundation.org; amit.shah at redhat.com;
Hansen,
> > Dave; cornelia.huck at de.ibm.com; pbonzini at redhat.com;
> > david at redhat.com; aarcange at redhat.com; dgilbert at redhat.com;
> > quintela at redhat.com
> > Subject: Re: [virtio-dev] Re: [PATCH v6 kernel 2/5] virtio-balloon:
define new
> > feature bit and head struct
> > 
> > On Fri, Jan 13, 2017 at 09:24:22AM +0000, Li, Liang Z wrote:
> > > > On Wed, Dec 21, 2016 at 02:52:25PM +0800, Liang Li wrote:
> > > > > Add a new feature which supports sending the page
information with
> > > > > range array. The current implementation uses PFNs
array, which is
> > > > > not very efficient. Using ranges can improve the
performance of
> > > > > inflating/deflating significantly.
> > > > >
> > > > > Signed-off-by: Liang Li <liang.z.li at intel.com>
> > > > > Cc: Michael S. Tsirkin <mst at redhat.com>
> > > > > Cc: Paolo Bonzini <pbonzini at redhat.com>
> > > > > Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> > > > > Cc: Amit Shah <amit.shah at redhat.com>
> > > > > Cc: Dave Hansen <dave.hansen at intel.com>
> > > > > Cc: Andrea Arcangeli <aarcange at redhat.com>
> > > > > Cc: David Hildenbrand <david at redhat.com>
> > > > > ---
> > > > >  include/uapi/linux/virtio_balloon.h | 12 ++++++++++++
> > > > >  1 file changed, 12 insertions(+)
> > > > >
> > > > > diff --git a/include/uapi/linux/virtio_balloon.h
> > > > > b/include/uapi/linux/virtio_balloon.h
> > > > > index 343d7dd..2f850bf 100644
> > > > > --- a/include/uapi/linux/virtio_balloon.h
> > > > > +++ b/include/uapi/linux/virtio_balloon.h
> > > > > @@ -34,10 +34,14 @@
> > > > >  #define VIRTIO_BALLOON_F_MUST_TELL_HOST	0 /* Tell
before
> > > > reclaiming pages */
> > > > >  #define VIRTIO_BALLOON_F_STATS_VQ	1 /* Memory Stats
virtqueue
> > > > */
> > > > >  #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM	2 /* Deflate
> > balloon
> > > > on OOM */
> > > > > +#define VIRTIO_BALLOON_F_PAGE_RANGE	3 /* Send page
info
> > > > with ranges */
> > > > >
> > > > >  /* Size of a PFN in the balloon interface. */  #define
> > > > > VIRTIO_BALLOON_PFN_SHIFT 12
> > > > >
> > > > > +/* Bits width for the length of the pfn range */
> > > >
> > > > What does this mean? Couldn't figure it out.
> > > >
> > > > > +#define VIRTIO_BALLOON_NR_PFN_BITS 12
> > > > > +
> > > > >  struct virtio_balloon_config {
> > > > >  	/* Number of pages host wants Guest to give up. */
> > > > >  	__u32 num_pages;
> > > > > @@ -82,4 +86,12 @@ struct virtio_balloon_stat {
> > > > >  	__virtio64 val;
> > > > >  } __attribute__((packed));
> > > > >
> > > > > +/* Response header structure */
> > > > > +struct virtio_balloon_resp_hdr {
> > > > > +	__le64 cmd : 8; /* Distinguish different requests
type */
> > > > > +	__le64 flag: 8; /* Mark status for a specific request
type */
> > > > > +	__le64 id : 16; /* Distinguish requests of a specific
type */
> > > > > +	__le64 data_len: 32; /* Length of the following data,
in bytes
> > > > > +*/
> > > >
> > > > This use of __le64 makes no sense.  Just use u8/le16/le32
pls.
> > > >
> > >
> > > Got it, will change in the next version.
> > >
> > > And could help take a look at other parts? as well as the QEMU
part.
> > >
> > > Thanks!
> > > Liang
> > 
> > Yes but first I would like to understand how come no fields in this
new
> > structure come up if I search for them in the following patch. I
don't see why
> 
> It's not true, all of the field will be referenced in the following
patches except
> the 'reserved' filed.
But none of these are used in the following patch 3.
> > should I waste time on reviewing the implementation if the interface
isn't
> > reasonable. You don't have to waste it too - just send RFC patches
with the
> > header until we can agree on it.
> 
> OK. I will post the header part separately.
> 
> Thanks!
> Liang
> > 
> > --
> > MST
> > 
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: virtio-dev-unsubscribe at lists.oasis-open.org
> > For additional commands, e-mail: virtio-dev-help at
lists.oasis-open.org