linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@kernel.org>,
	Alexander Duyck <alexander.duyck@gmail.com>
Cc: virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org,
	mst@redhat.com, dave.hansen@intel.com,
	linux-kernel@vger.kernel.org, willy@infradead.org,
	linux-mm@kvack.org, vbabka@suse.cz, akpm@linux-foundation.org,
	mgorman@techsingularity.net,
	linux-arm-kernel@lists.infradead.org, osalvador@suse.de,
	yang.zhang.wz@gmail.com, pagupta@redhat.com,
	konrad.wilk@oracle.com, nitesh@redhat.com, riel@surriel.com,
	lcapitulino@redhat.com, wei.w.wang@intel.com,
	aarcange@redhat.com, pbonzini@redhat.com,
	dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com
Subject: Re: [PATCH v10 0/6] mm / virtio: Provide support for unused page reporting
Date: Tue, 24 Sep 2019 17:32:26 +0200	[thread overview]
Message-ID: <d2a7acdd-3bb9-05c9-42d0-70a500801cd6@redhat.com> (raw)
In-Reply-To: <20190924142342.GX23050@dhcp22.suse.cz>

On 24.09.19 16:23, Michal Hocko wrote:
> On Wed 18-09-19 10:52:25, Alexander Duyck wrote:
> [...]
>> In order to try and keep the time needed to find a non-reported page to
>> a minimum we maintain a "reported_boundary" pointer. This pointer is used
>> by the get_unreported_pages iterator to determine at what point it should
>> resume searching for non-reported pages. In order to guarantee pages do
>> not get past the scan I have modified add_to_free_list_tail so that it
>> will not insert pages behind the reported_boundary.
>>
>> If another process needs to perform a massive manipulation of the free
>> list, such as compaction, it can either reset a given individual boundary
>> which will push the boundary back to the list_head, or it can clear the
>> bit indicating the zone is actively processing which will result in the
>> reporting process resetting all of the boundaries for a given zone.
> 
> Is this any different from the previous version? The last review
> feedback (both from me and Mel) was that we are not happy to have an
> externally imposed constrains on how the page allocator is supposed to
> maintain its free lists.
> 
> If this is really the only way to go forward then I would like to hear
> very convincing arguments about other approaches not being feasible.

Adding to what Alexander said, I don't consider the other approaches
(especially the bitmap-based approach Nitesh is currently working on)
infeasible. There might be more rough edges (e.g., sparse zones) and
eventually sometimes a little more work to be done, but definitely
feasible. Incorporating stuff into the buddy might make some tasks
(e.g., identify free pages) more efficient.

I still somewhat like the idea of capturing hints of free pages (in
whatever data structure) and then going over the hints, seeing if the
pages are still free. Then only temporarily isolating the still-free
pages, reporting them, and un-isolating them after they were reported. I
like the idea that the pages are not fake-allocated but only temporarily
blocked. That works nicely e.g., with the movable zone (contain only
movable data).

But anyhow, after decades of people working on free page
hinting/reporting, I am happy with anything that gets accepted upstream :D

-- 

Thanks,

David / dhildenb

  parent reply	other threads:[~2019-09-24 15:32 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-18 17:52 Alexander Duyck
2019-09-18 17:52 ` [PATCH v10 1/6] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-09-18 17:52 ` [PATCH v10 2/6] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-09-18 17:52 ` [PATCH v10 3/6] mm: Introduce Reported pages Alexander Duyck
2019-09-21 15:25   ` [mm] 0f5b256b2c: will-it-scale.per_process_ops -1.2% regression kernel test robot
2019-09-23  8:15   ` [PATCH v10 3/6] mm: Introduce Reported pages Michael S. Tsirkin
2019-09-23 14:50     ` Alexander Duyck
2019-09-23 15:00       ` Michael S. Tsirkin
2019-09-23 15:28         ` Alexander Duyck
2019-09-23 15:37           ` Michael S. Tsirkin
2019-09-23 15:45             ` David Hildenbrand
2019-09-23 15:47               ` David Hildenbrand
2019-09-23 15:50                 ` Michael S. Tsirkin
2019-09-23 15:53                   ` David Hildenbrand
2019-09-23 15:49               ` Michael S. Tsirkin
2019-09-23 16:39               ` Alexander Duyck
2019-09-18 17:52 ` [PATCH v10 4/6] mm: Add device side and notifier for unused page reporting Alexander Duyck
2019-09-18 17:53 ` [PATCH v10 5/6] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-09-18 17:58   ` Michael S. Tsirkin
2019-09-18 18:05     ` Alexander Duyck
2019-09-18 17:53 ` [PATCH v10 6/6] virtio-balloon: Add support for providing unused page reports to host Alexander Duyck
2019-09-18 17:53 ` [PATCH v10 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature Alexander Duyck
2019-09-18 17:53 ` [PATCH v10 QEMU 2/3] virtio-balloon: Add bit to notify guest of unused page reporting Alexander Duyck
2019-09-18 17:53 ` [PATCH v10 QEMU 3/3] virtio-balloon: Provide a interface for " Alexander Duyck
2019-09-24 14:23 ` [PATCH v10 0/6] mm / virtio: Provide support " Michal Hocko
2019-09-24 15:20   ` Alexander Duyck
2019-09-26 12:22     ` Michal Hocko
2019-09-26 15:13       ` Alexander Duyck
2019-09-24 15:32   ` David Hildenbrand [this message]
2019-09-24 15:51     ` Nitesh Narayan Lal
2019-09-24 17:07     ` Alexander Duyck
2019-09-24 17:28       ` David Hildenbrand

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d2a7acdd-3bb9-05c9-42d0-70a500801cd6@redhat.com \
    --to=david@redhat.com \
    --cc=aarcange@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.duyck@gmail.com \
    --cc=alexander.h.duyck@linux.intel.com \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@intel.com \
    --cc=konrad.wilk@oracle.com \
    --cc=kvm@vger.kernel.org \
    --cc=lcapitulino@redhat.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@kernel.org \
    --cc=mst@redhat.com \
    --cc=nitesh@redhat.com \
    --cc=osalvador@suse.de \
    --cc=pagupta@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=riel@surriel.com \
    --cc=vbabka@suse.cz \
    --cc=virtio-dev@lists.oasis-open.org \
    --cc=wei.w.wang@intel.com \
    --cc=willy@infradead.org \
    --cc=yang.zhang.wz@gmail.com \
    --subject='Re: [PATCH v10 0/6] mm / virtio: Provide support for unused page reporting' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).