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From:   SeongJae Park <sjpark@amazon.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC:     SeongJae Park <sjpark@amazon.com>, <roger.pau@citrix.com>,
        SeongJae Park <sjpark@amazon.de>, <axboe@kernel.dk>,
        <aliguori@amazon.com>, <amit@kernel.org>, <mheyne@amazon.de>,
        <linux-block@vger.kernel.org>, <xen-devel@lists.xenproject.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] xen-blkback: add a parameter for disabling of persistent grants
Date:   Thu, 24 Sep 2020 08:26:53 +0200
Message-ID: <20200924062653.9449-1-sjpark@amazon.com>
In-Reply-To: <20200923200930.GB11767@char.us.oracle.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Wed, 23 Sep 2020 16:09:30 -0400 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:

> On Tue, Sep 22, 2020 at 09:01:25AM +0200, 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 overhead[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.
> 
> Would it be better suited to have it per guest?

The latest version of this patchset[1] supports blkfront side disablement.
Could that partially solves your concern?

[1] https://lore.kernel.org/xen-devel/20200923061841.20531-1-sjpark@amazon.com/


Thanks,
SeongJae Park