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

Message ID	20180813140114.20126-1-jgross@suse.com (mailing list archive)
Headers	show Return-Path: <linux-block-owner@kernel.org> From: Juergen Gross <jgross@suse.com> To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org Cc: konrad.wilk@oracle.com, roger.pau@citrix.com, axboe@kernel.dk, boris.ostrovsky@oracle.com, Juergen Gross <jgross@suse.com> Subject: [PATCH v3 0/5] xen/blk: persistent grant rework Date: Mon, 13 Aug 2018 16:01:09 +0200 Message-Id: <20180813140114.20126-1-jgross@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk
Series	xen/blk: persistent grant rework \| expand [v3,0/5] xen/blk: persistent grant rework [v3,1/5] xen/blkback: don't keep persistent grants too long [v3,2/5] xen/blkfront: cleanup stale persistent grants [v3,3/5] xen/blkfront: reorder tests in xlblk_init() [v3,4/5] xen/blkback: move persistent grants flags to bool [v3,5/5] xen/blkback: remove unused pers_gnts_lock from struct xen_blkif_ring

Message ID

20180813140114.20126-1-jgross@suse.com (mailing list archive)

Headers

From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
        linux-block@vger.kernel.org
Cc: konrad.wilk@oracle.com, roger.pau@citrix.com, axboe@kernel.dk,
        boris.ostrovsky@oracle.com, Juergen Gross <jgross@suse.com>
Subject: [PATCH v3 0/5] xen/blk: persistent grant rework
Date: Mon, 13 Aug 2018 16:01:09 +0200
Message-Id: <20180813140114.20126-1-jgross@suse.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-block-owner@vger.kernel.org
Precedence: bulk

Series

xen/blk: persistent grant rework | expand

Message

Juergen Gross Aug. 13, 2018, 2:01 p.m. UTC

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(-)

Comments

Roger Pau Monné Aug. 17, 2018, 3:59 p.m. UTC | #1

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.

Juergen Gross Aug. 24, 2018, 1:52 p.m. UTC | #2

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

Konrad Rzeszutek Wilk Aug. 27, 2018, 4:10 p.m. UTC | #3

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