[PATCH v3 0/5] xen/blk: persistent grant rework

[PATCH v3 0/5] xen/blk: persistent grant rework

[Juergen Gross]

Persistent grants are used in the Xen's blkfront/blkback drivers to
avoid mapping/unmapping of I/O buffers in the backend for each I/O.

While this speeds up processing quite a bit there are problems related
to persistent grants in some configurations: domains with multiple
block devices making use of persistent grants might suffer from a lack
of grants if each of the block devices experienced a high I/O load at
some time. This is due to the number of persistent grants per device
only to be limited by a rather high maximum value, but never being
released even in case of longer times without any I/O.

This series modifies xen-blkback to unmap any domU page mapped via a
persistent grant after a timeout (default: 60 seconds). The timeout
is set to its default value again when a persistent grant has been
used for an I/O.

xen-blkfront is modified to scan every 10 seconds for persistent grants
not in use by blkback any more and to remove such grants.

The last 3 patches are small cleanups of blkfront and blkback drivers.

V3:
- patch 1: make timeout parameter static

V2:
- patch 1: added new module parameter doc
- patch 1: removed PERSISTENT_GNT_WAS_ACTIVE flag
- patch 2: removed global worker active flag
- added new patch 4

Juergen Gross (5):
  xen/blkback: don't keep persistent grants too long
  xen/blkfront: cleanup stale persistent grants
  xen/blkfront: reorder tests in xlblk_init()
  xen/blkback: move persistent grants flags to bool
  xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring

 Documentation/ABI/testing/sysfs-driver-xen-blkback |  10 ++
 drivers/block/xen-blkback/blkback.c                |  99 ++++++++++---------
 drivers/block/xen-blkback/common.h                 |  14 +--
 drivers/block/xen-blkfront.c                       | 110 ++++++++++++++++++---
 4 files changed, 163 insertions(+), 70 deletions(-)

-- 
2.13.7


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Konrad Rzeszutek Wilk]

On Fri, Aug 24, 2018 at 03:52:23PM +0200, Juergen Gross wrote:
> On 17/08/18 17:59, Roger Pau Monn=E9 wrote:
> > On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> >> Persistent grants are used in the Xen's blkfront/blkback drivers to
> >> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> >>
> >> While this speeds up processing quite a bit there are problems relat=
ed
> >> to persistent grants in some configurations: domains with multiple
> >> block devices making use of persistent grants might suffer from a la=
ck
> >> of grants if each of the block devices experienced a high I/O load a=
t
> >> some time. This is due to the number of persistent grants per device
> >> only to be limited by a rather high maximum value, but never being
> >> released even in case of longer times without any I/O.
> >>
> >> This series modifies xen-blkback to unmap any domU page mapped via a
> >> persistent grant after a timeout (default: 60 seconds). The timeout
> >> is set to its default value again when a persistent grant has been
> >> used for an I/O.
> >>
> >> xen-blkfront is modified to scan every 10 seconds for persistent gra=
nts
> >> not in use by blkback any more and to remove such grants.
> >>
> >> The last 3 patches are small cleanups of blkfront and blkback driver=
s.
> >>
> >> V3:
> >> - patch 1: make timeout parameter static
> >=20
> > Konrad if you are OK with this series, could you please send a pull
> > request to Jens?
>=20
> Ping?

Yes, let me do that now.
>=20
>=20
> Juergen

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Konrad Rzeszutek Wilk]

On Fri, Aug 24, 2018 at 03:52:23PM +0200, Juergen Gross wrote:
> On 17/08/18 17:59, Roger Pau Monné wrote:
> > On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> >> Persistent grants are used in the Xen's blkfront/blkback drivers to
> >> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> >>
> >> While this speeds up processing quite a bit there are problems related
> >> to persistent grants in some configurations: domains with multiple
> >> block devices making use of persistent grants might suffer from a lack
> >> of grants if each of the block devices experienced a high I/O load at
> >> some time. This is due to the number of persistent grants per device
> >> only to be limited by a rather high maximum value, but never being
> >> released even in case of longer times without any I/O.
> >>
> >> This series modifies xen-blkback to unmap any domU page mapped via a
> >> persistent grant after a timeout (default: 60 seconds). The timeout
> >> is set to its default value again when a persistent grant has been
> >> used for an I/O.
> >>
> >> xen-blkfront is modified to scan every 10 seconds for persistent grants
> >> not in use by blkback any more and to remove such grants.
> >>
> >> The last 3 patches are small cleanups of blkfront and blkback drivers.
> >>
> >> V3:
> >> - patch 1: make timeout parameter static
> > 
> > Konrad if you are OK with this series, could you please send a pull
> > request to Jens?
> 
> Ping?

Yes, let me do that now.
> 
> 
> Juergen

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Konrad Rzeszutek Wilk]

On Fri, Aug 24, 2018 at 03:52:23PM +0200, Juergen Gross wrote:
> On 17/08/18 17:59, Roger Pau Monné wrote:
> > On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> >> Persistent grants are used in the Xen's blkfront/blkback drivers to
> >> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> >>
> >> While this speeds up processing quite a bit there are problems related
> >> to persistent grants in some configurations: domains with multiple
> >> block devices making use of persistent grants might suffer from a lack
> >> of grants if each of the block devices experienced a high I/O load at
> >> some time. This is due to the number of persistent grants per device
> >> only to be limited by a rather high maximum value, but never being
> >> released even in case of longer times without any I/O.
> >>
> >> This series modifies xen-blkback to unmap any domU page mapped via a
> >> persistent grant after a timeout (default: 60 seconds). The timeout
> >> is set to its default value again when a persistent grant has been
> >> used for an I/O.
> >>
> >> xen-blkfront is modified to scan every 10 seconds for persistent grants
> >> not in use by blkback any more and to remove such grants.
> >>
> >> The last 3 patches are small cleanups of blkfront and blkback drivers.
> >>
> >> V3:
> >> - patch 1: make timeout parameter static
> > 
> > Konrad if you are OK with this series, could you please send a pull
> > request to Jens?
> 
> Ping?

Yes, let me do that now.
> 
> 
> Juergen

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Juergen Gross]

On 17/08/18 17:59, Roger Pau Monné wrote:
> On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
>> Persistent grants are used in the Xen's blkfront/blkback drivers to
>> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
>>
>> While this speeds up processing quite a bit there are problems related
>> to persistent grants in some configurations: domains with multiple
>> block devices making use of persistent grants might suffer from a lack
>> of grants if each of the block devices experienced a high I/O load at
>> some time. This is due to the number of persistent grants per device
>> only to be limited by a rather high maximum value, but never being
>> released even in case of longer times without any I/O.
>>
>> This series modifies xen-blkback to unmap any domU page mapped via a
>> persistent grant after a timeout (default: 60 seconds). The timeout
>> is set to its default value again when a persistent grant has been
>> used for an I/O.
>>
>> xen-blkfront is modified to scan every 10 seconds for persistent grants
>> not in use by blkback any more and to remove such grants.
>>
>> The last 3 patches are small cleanups of blkfront and blkback drivers.
>>
>> V3:
>> - patch 1: make timeout parameter static
> 
> Konrad if you are OK with this series, could you please send a pull
> request to Jens?

Ping?


Juergen

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Juergen Gross]

On 17/08/18 17:59, Roger Pau Monné wrote:
> On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
>> Persistent grants are used in the Xen's blkfront/blkback drivers to
>> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
>>
>> While this speeds up processing quite a bit there are problems related
>> to persistent grants in some configurations: domains with multiple
>> block devices making use of persistent grants might suffer from a lack
>> of grants if each of the block devices experienced a high I/O load at
>> some time. This is due to the number of persistent grants per device
>> only to be limited by a rather high maximum value, but never being
>> released even in case of longer times without any I/O.
>>
>> This series modifies xen-blkback to unmap any domU page mapped via a
>> persistent grant after a timeout (default: 60 seconds). The timeout
>> is set to its default value again when a persistent grant has been
>> used for an I/O.
>>
>> xen-blkfront is modified to scan every 10 seconds for persistent grants
>> not in use by blkback any more and to remove such grants.
>>
>> The last 3 patches are small cleanups of blkfront and blkback drivers.
>>
>> V3:
>> - patch 1: make timeout parameter static
> 
> Konrad if you are OK with this series, could you please send a pull
> request to Jens?

Ping?


Juergen

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Roger Pau Monné]

On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> Persistent grants are used in the Xen's blkfront/blkback drivers to
> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> 
> While this speeds up processing quite a bit there are problems related
> to persistent grants in some configurations: domains with multiple
> block devices making use of persistent grants might suffer from a lack
> of grants if each of the block devices experienced a high I/O load at
> some time. This is due to the number of persistent grants per device
> only to be limited by a rather high maximum value, but never being
> released even in case of longer times without any I/O.
> 
> This series modifies xen-blkback to unmap any domU page mapped via a
> persistent grant after a timeout (default: 60 seconds). The timeout
> is set to its default value again when a persistent grant has been
> used for an I/O.
> 
> xen-blkfront is modified to scan every 10 seconds for persistent grants
> not in use by blkback any more and to remove such grants.
> 
> The last 3 patches are small cleanups of blkfront and blkback drivers.
> 
> V3:
> - patch 1: make timeout parameter static

Konrad if you are OK with this series, could you please send a pull
request to Jens?

Thanks, Roger.

Re: [PATCH v3 0/5] xen/blk: persistent grant rework

[Roger Pau Monné]

On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> Persistent grants are used in the Xen's blkfront/blkback drivers to
> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> 
> While this speeds up processing quite a bit there are problems related
> to persistent grants in some configurations: domains with multiple
> block devices making use of persistent grants might suffer from a lack
> of grants if each of the block devices experienced a high I/O load at
> some time. This is due to the number of persistent grants per device
> only to be limited by a rather high maximum value, but never being
> released even in case of longer times without any I/O.
> 
> This series modifies xen-blkback to unmap any domU page mapped via a
> persistent grant after a timeout (default: 60 seconds). The timeout
> is set to its default value again when a persistent grant has been
> used for an I/O.
> 
> xen-blkfront is modified to scan every 10 seconds for persistent grants
> not in use by blkback any more and to remove such grants.
> 
> The last 3 patches are small cleanups of blkfront and blkback drivers.
> 
> V3:
> - patch 1: make timeout parameter static

Konrad if you are OK with this series, could you please send a pull
request to Jens?

Thanks, Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

[PATCH v3 0/5] xen/blk: persistent grant rework

[Juergen Gross]

Persistent grants are used in the Xen's blkfront/blkback drivers to
avoid mapping/unmapping of I/O buffers in the backend for each I/O.

While this speeds up processing quite a bit there are problems related
to persistent grants in some configurations: domains with multiple
block devices making use of persistent grants might suffer from a lack
of grants if each of the block devices experienced a high I/O load at
some time. This is due to the number of persistent grants per device
only to be limited by a rather high maximum value, but never being
released even in case of longer times without any I/O.

This series modifies xen-blkback to unmap any domU page mapped via a
persistent grant after a timeout (default: 60 seconds). The timeout
is set to its default value again when a persistent grant has been
used for an I/O.

xen-blkfront is modified to scan every 10 seconds for persistent grants
not in use by blkback any more and to remove such grants.

The last 3 patches are small cleanups of blkfront and blkback drivers.

V3:
- patch 1: make timeout parameter static

V2:
- patch 1: added new module parameter doc
- patch 1: removed PERSISTENT_GNT_WAS_ACTIVE flag
- patch 2: removed global worker active flag
- added new patch 4

Juergen Gross (5):
  xen/blkback: don't keep persistent grants too long
  xen/blkfront: cleanup stale persistent grants
  xen/blkfront: reorder tests in xlblk_init()
  xen/blkback: move persistent grants flags to bool
  xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring

 Documentation/ABI/testing/sysfs-driver-xen-blkback |  10 ++
 drivers/block/xen-blkback/blkback.c                |  99 ++++++++++---------
 drivers/block/xen-blkback/common.h                 |  14 +--
 drivers/block/xen-blkfront.c                       | 110 ++++++++++++++++++---
 4 files changed, 163 insertions(+), 70 deletions(-)

-- 
2.13.7