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From: "Durrant, Paul" <pdurrant@amazon.com>
To: "Park, Seongjae" <sjpark@amazon.com>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"roger.pau@citrix.com" <roger.pau@citrix.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "sj38.park@gmail.com" <sj38.park@gmail.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Park, Seongjae" <sjpark@amazon.com>
Subject: RE: [Xen-devel] [PATCH 0/2] xen/blkback: Aggressively shrink page pools if a memory pressure is detected
Date: Wed, 4 Dec 2019 11:52:04 +0000
Message-ID: <62c68f53cc0145ad9d0dfb167b50eac4@EX13D32EUC003.ant.amazon.com> (raw)
In-Reply-To: <20191204113419.2298-1-sjpark@amazon.com>

> -----Original Message-----
> From: Xen-devel <xen-devel-bounces@lists.xenproject.org> On Behalf Of
> SeongJae Park
> Sent: 04 December 2019 11:34
> To: konrad.wilk@oracle.com; roger.pau@citrix.com; axboe@kernel.dk
> Cc: sj38.park@gmail.com; xen-devel@lists.xenproject.org; linux-
> block@vger.kernel.org; linux-kernel@vger.kernel.org; Park, Seongjae
> <sjpark@amazon.com>
> Subject: [Xen-devel] [PATCH 0/2] xen/blkback: Aggressively shrink page
> pools if a memory pressure is detected
> 
> Each `blkif` has a free pages pool for the grant mapping.  The size of
> the pool starts from zero and be increased on demand while processing
> the I/O requests.  If current I/O requests handling is finished or 100
> milliseconds has passed since last I/O requests handling, it checks and
> shrinks the pool to not exceed the size limit, `max_buffer_pages`.
> 
> Therefore, `blkfront` running guests can cause a memory pressure in the
> `blkback` running guest by attaching arbitrarily large number of block
> devices and inducing I/O.

OOI... How do guests unilaterally cause the attachment of arbitrary numbers of PV devices?

  Paul


  parent reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-04 11:34 SeongJae Park
2019-12-04 11:34 ` [PATCH 1/2] " SeongJae Park
2019-12-04 11:34 ` [PATCH 2/2] blkback: Add a module parameter for aggressive pool shrinking duration SeongJae Park
2019-12-04 11:52 ` Durrant, Paul [this message]
2019-12-04 12:09   ` [Xen-devel] [PATCH 0/2] xen/blkback: Aggressively shrink page pools if a memory pressure is detected sjpark

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