From: SeongJae Park <sjpark@amazon.com>
To: "Jürgen Groß" <jgross@suse.com>
Cc: SeongJae Park <sjpark@amazon.com>, <konrad.wilk@oracle.com>,
<roger.pau@citrix.com>, SeongJae Park <sjpark@amazon.de>,
<axboe@kernel.dk>, <aliguori@amazon.com>, <amit@kernel.org>,
<mheyne@amazon.de>, <pdurrant@amazon.co.uk>,
<linux-block@vger.kernel.org>, <xen-devel@lists.xenproject.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/3] xen-blkback: add a parameter for disabling of persistent grants
Date: Tue, 22 Sep 2020 16:30:11 +0200 [thread overview]
Message-ID: <20200922143011.29568-1-sjpark@amazon.com> (raw)
In-Reply-To: <5d0f75f1-636e-e485-c616-bca47bd6932f@suse.com>
On Tue, 22 Sep 2020 16:25:57 +0200 "Jürgen Groß" <jgross@suse.com> wrote:
> On 22.09.20 16:15, SeongJae Park wrote:
> > From: SeongJae Park <sjpark@amazon.de>
> >
> > Persistent grants feature provides high scalability. On some small
> > systems, however, it could incur data copy overheads[1] and thus it is
> > required to be disabled. But, there is no option to disable it. For
> > the reason, this commit adds a module parameter for disabling of the
> > feature.
> >
> > [1] https://wiki.xen.org/wiki/Xen_4.3_Block_Protocol_Scalability
> >
> > Signed-off-by: Anthony Liguori <aliguori@amazon.com>
> > Signed-off-by: SeongJae Park <sjpark@amazon.de>
> > ---
> > .../ABI/testing/sysfs-driver-xen-blkback | 9 ++++++++
> > drivers/block/xen-blkback/xenbus.c | 22 ++++++++++++++-----
> > 2 files changed, 25 insertions(+), 6 deletions(-)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback
> > index ecb7942ff146..ac2947b98950 100644
> > --- a/Documentation/ABI/testing/sysfs-driver-xen-blkback
> > +++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback
> > @@ -35,3 +35,12 @@ Description:
> > controls the duration in milliseconds that blkback will not
> > cache any page not backed by a grant mapping.
> > The default is 10ms.
> > +
> > +What: /sys/module/xen_blkback/parameters/feature_persistent
> > +Date: September 2020
> > +KernelVersion: 5.10
> > +Contact: SeongJae Park <sjpark@amazon.de>
> > +Description:
> > + Whether to enable the persistent grants feature or not. Note
> > + that this option only takes effect on newly created backends.
> > + The default is Y (enable).
> > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
> > index b9aa5d1ac10b..f4c8827fa0ad 100644
> > --- a/drivers/block/xen-blkback/xenbus.c
> > +++ b/drivers/block/xen-blkback/xenbus.c
> > @@ -474,6 +474,12 @@ static void xen_vbd_free(struct xen_vbd *vbd)
> > vbd->bdev = NULL;
> > }
> >
> > +/* Enable the persistent grants feature. */
> > +static bool feature_persistent = true;
> > +module_param(feature_persistent, bool, 0644);
> > +MODULE_PARM_DESC(feature_persistent,
> > + "Enables the persistent grants feature");
> > +
> > static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
> > unsigned major, unsigned minor, int readonly,
> > int cdrom)
> > @@ -519,6 +525,8 @@ static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
> > if (q && blk_queue_secure_erase(q))
> > vbd->discard_secure = true;
> >
> > + vbd->feature_gnt_persistent = feature_persistent ? 1 : 0;
>
> Just assign the value instead of using the ternary operator?
I will do so in the next version.
>
> With that changed you can add my
>
> Reviewed-by: Juergen Gross <jgross@suse.com>
Thank you for your kind, quick, and detailed review!
Thanks,
SeongJae Park
next prev parent reply other threads:[~2020-09-22 14:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 14:15 [PATCH v3 0/3] xen-blk(back|front): Let users disable persistent grants SeongJae Park
2020-09-22 14:15 ` [PATCH v3 1/3] xen-blkback: add a parameter for disabling of " SeongJae Park
2020-09-22 14:25 ` Jürgen Groß
2020-09-22 14:30 ` SeongJae Park [this message]
2020-09-22 14:15 ` [PATCH v3 2/3] xen-blkfront: " SeongJae Park
2020-09-22 14:27 ` Jürgen Groß
2020-09-22 14:31 ` SeongJae Park
2020-09-22 14:15 ` [PATCH v3 3/3] xen-blkfront: Apply changed parameter name to the document SeongJae Park
2020-09-22 14:27 ` Jürgen Groß
2020-09-22 14:44 ` Roger Pau Monné
2020-09-22 15:02 ` SeongJae Park
2020-09-22 14:45 ` [PATCH v3 0/3] xen-blk(back|front): Let users disable persistent grants Roger Pau Monné
2020-09-22 14:52 ` SeongJae Park
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