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From: Alexander Duyck <alexander.duyck@gmail.com>
To: David Hildenbrand <david@redhat.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>,
	kvm list <kvm@vger.kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Dave Hansen <dave.hansen@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Yang Zhang <yang.zhang.wz@gmail.com>,
	pagupta@redhat.com, Rik van Riel <riel@surriel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	lcapitulino@redhat.com, wei.w.wang@intel.com,
	Andrea Arcangeli <aarcange@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	dan.j.williams@intel.com,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>
Subject: Re: [PATCH v1 0/6] mm / virtio: Provide support for paravirtual waste page treatment
Date: Tue, 25 Jun 2019 09:09:03 -0700
Message-ID: <CAKgT0Ue4k_MHiAqMM0kyBBnPCB+828tXE2HfiZ9N1gKYayQcow@mail.gmail.com> (raw)
In-Reply-To: <ff133df4-6291-bece-3d8d-dc3f12f398cf@redhat.com>

On Tue, Jun 25, 2019 at 12:42 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 20.06.19 00:32, Alexander Duyck wrote:
> > This series provides an asynchronous means of hinting to a hypervisor
> > that a guest page is no longer in use and can have the data associated
> > with it dropped. To do this I have implemented functionality that allows
> > for what I am referring to as waste page treatment.
> >
> > I have based many of the terms and functionality off of waste water
> > treatment, the idea for the similarity occurred to me after I had reached
> > the point of referring to the hints as "bubbles", as the hints used the
> > same approach as the balloon functionality but would disappear if they
> > were touched, as a result I started to think of the virtio device as an
> > aerator. The general idea with all of this is that the guest should be
> > treating the unused pages so that when they end up heading "downstream"
> > to either another guest, or back at the host they will not need to be
> > written to swap.
> >
> > When the number of "dirty" pages in a given free_area exceeds our high
> > water mark, which is currently 32, we will schedule the aeration task to
> > start going through and scrubbing the zone. While the scrubbing is taking
> > place a boundary will be defined that we use to seperate the "aerated"
> > pages from the "dirty" ones. We use the ZONE_AERATION_ACTIVE bit to flag
> > when these boundaries are in place.
>
> I still *detest* the terminology, sorry. Can't you come up with a
> simpler terminology that makes more sense in the context of operating
> systems and pages we want to hint to the hypervisor? (that is the only
> use case you are using it for so far)

I'm open to suggestions. The terminology is just what I went with as I
had gone from balloon to thinking of this as a bubble since it was a
balloon without the deflate logic. From there I got to aeration since
it is filling the buddy allocator with those bubbles.

> >
> > I am leaving a number of things hard-coded such as limiting the lowest
> > order processed to PAGEBLOCK_ORDER, and have left it up to the guest to
> > determine what batch size it wants to allocate to process the hints.
> >
> > My primary testing has just been to verify the memory is being freed after
> > allocation by running memhog 32g in the guest and watching the total free
> > memory via /proc/meminfo on the host. With this I have verified most of
> > the memory is freed after each iteration. As far as performance I have
> > been mainly focusing on the will-it-scale/page_fault1 test running with
> > 16 vcpus. With that I have seen a less than 1% difference between the
>
> 1% throughout all benchmarks? Guess that is quite good.

That is the general idea. What I wanted to avoid was this introducing
any significant slowdown, especially in the case where we weren't
using it.

> > base kernel without these patches, with the patches and virtio-balloon
> > disabled, and with the patches and virtio-balloon enabled with hinting.
> >
> > Changes from the RFC:
> > Moved aeration requested flag out of aerator and into zone->flags.
> > Moved boundary out of free_area and into local variables for aeration.
> > Moved aeration cycle out of interrupt and into workqueue.
> > Left nr_free as total pages instead of splitting it between raw and aerated.
> > Combined size and physical address values in virtio ring into one 64b value.
> > Restructured the patch set to reduce patches from 11 to 6.
> >
>
> I'm planning to look into the details, but will be on PTO for two weeks
> starting this Saturday (and still have other things to finish first :/ ).

Thanks. No rush. I will be on PTO for the next couple of weeks myself.

> > ---
> >
> > Alexander Duyck (6):
> >       mm: Adjust shuffle code to allow for future coalescing
> >       mm: Move set/get_pcppage_migratetype to mmzone.h
> >       mm: Use zone and order instead of free area in free_list manipulators
> >       mm: Introduce "aerated" pages
> >       mm: Add logic for separating "aerated" pages from "raw" pages
> >       virtio-balloon: Add support for aerating memory via hinting
> >
> >
> >  drivers/virtio/Kconfig              |    1
> >  drivers/virtio/virtio_balloon.c     |  110 ++++++++++++++
> >  include/linux/memory_aeration.h     |  118 +++++++++++++++
> >  include/linux/mmzone.h              |  113 +++++++++------
> >  include/linux/page-flags.h          |    8 +
> >  include/uapi/linux/virtio_balloon.h |    1
> >  mm/Kconfig                          |    5 +
> >  mm/Makefile                         |    1
> >  mm/aeration.c                       |  270 +++++++++++++++++++++++++++++++++++
> >  mm/page_alloc.c                     |  203 ++++++++++++++++++--------
> >  mm/shuffle.c                        |   24 ---
> >  mm/shuffle.h                        |   35 +++++
> >  12 files changed, 753 insertions(+), 136 deletions(-)
> >  create mode 100644 include/linux/memory_aeration.h
> >  create mode 100644 mm/aeration.c
>
> Compared to
>
>  17 files changed, 838 insertions(+), 86 deletions(-)
>  create mode 100644 include/linux/memory_aeration.h
>  create mode 100644 mm/aeration.c
>
> this looks like a good improvement :)

Thanks.

- Alex

  parent reply index

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-19 22:32 Alexander Duyck
2019-06-19 22:33 ` [PATCH v1 1/6] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-06-25  7:55   ` David Hildenbrand
2019-06-28 19:49     ` Alexander Duyck
2019-06-25 18:25   ` Dave Hansen
2019-06-25 18:26   ` Dave Hansen
2019-06-19 22:33 ` [PATCH v1 2/6] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-06-25 18:28   ` Dave Hansen
2019-06-28 19:55     ` Alexander Duyck
2019-06-19 22:33 ` [PATCH v1 3/6] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-06-25 18:36   ` Dave Hansen
2019-06-19 22:33 ` [PATCH v1 4/6] mm: Introduce "aerated" pages Alexander Duyck
2019-06-25 19:45   ` Dave Hansen
2019-07-08 17:32     ` Alexander Duyck
2019-06-19 22:33 ` [PATCH v1 5/6] mm: Add logic for separating "aerated" pages from "raw" pages Alexander Duyck
2019-06-25 20:24   ` Dave Hansen
2019-07-08 19:02     ` Alexander Duyck
2019-07-08 19:36       ` Dave Hansen
2019-07-08 22:02         ` Alexander Duyck
2019-06-19 22:33 ` [PATCH v1 6/6] virtio-balloon: Add support for aerating memory via hinting Alexander Duyck
2019-07-16  9:55   ` Michael S. Tsirkin
2019-07-16 14:00     ` Dave Hansen
2019-07-16 14:12       ` David Hildenbrand
2019-07-16 14:17         ` David Hildenbrand
2019-07-16 15:04           ` Michael S. Tsirkin
2019-07-16 14:41         ` Dave Hansen
2019-07-16 15:01           ` Wang, Wei W
2019-07-16 16:12             ` Michael S. Tsirkin
2019-07-16 15:02           ` David Hildenbrand
2019-07-16 15:37     ` Alexander Duyck
2019-07-16 16:07       ` Michael S. Tsirkin
2019-07-16 16:54         ` Alexander Duyck
2019-07-16 17:41           ` Michael S. Tsirkin
2019-07-16 21:06             ` Alexander Duyck
2019-07-17 10:28               ` Michael S. Tsirkin
2019-07-17 16:43                 ` Alexander Duyck
2019-07-18  5:13                   ` Michael S. Tsirkin
2019-07-18 15:34                     ` Alexander Duyck
2019-07-18 16:03                       ` Nitesh Narayan Lal
2019-07-18 20:27                         ` Michael S. Tsirkin
2019-07-18 16:07                       ` Michael S. Tsirkin
2019-07-18 20:29                         ` Alexander Duyck
2019-07-18 20:37                           ` Michael S. Tsirkin
2019-07-18 20:54                             ` Alexander Duyck
2019-07-18 20:24                       ` Michael S. Tsirkin
2019-07-18 20:34                         ` Alexander Duyck
2019-07-18 20:48                           ` Michael S. Tsirkin
2019-07-18 21:09                             ` Alexander Duyck
2019-06-19 22:37 ` [PATCH v1 QEMU] QEMU: Provide a interface for hinting based off of the balloon infrastructure Alexander Duyck
2019-06-25  7:42 ` [PATCH v1 0/6] mm / virtio: Provide support for paravirtual waste page treatment David Hildenbrand
2019-06-25 14:10   ` Dave Hansen
2019-06-25 17:00     ` Alexander Duyck
2019-06-25 18:12       ` David Hildenbrand
2019-06-25 18:22       ` Dave Hansen
2019-07-15  9:41         ` David Hildenbrand
2019-07-15 14:57           ` Alexander Duyck
2019-06-25 16:09   ` Alexander Duyck [this message]
2019-06-26  9:01   ` Christophe de Dinechin
2019-06-26  9:12     ` David Hildenbrand

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