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From: Mel Gorman <mgorman@techsingularity.net>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: kvm@vger.kernel.org, david@redhat.com, mst@redhat.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org, yang.zhang.wz@gmail.com,
	pagupta@redhat.com, konrad.wilk@oracle.com, nitesh@redhat.com,
	riel@surriel.com, willy@infradead.org, lcapitulino@redhat.com,
	dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com,
	pbonzini@redhat.com, dan.j.williams@intel.com, mhocko@kernel.org,
	alexander.h.duyck@linux.intel.com, vbabka@suse.cz,
	osalvador@suse.de
Subject: Re: [PATCH v17 8/9] mm/page_reporting: Add budget limit on how many pages can be reported per pass
Date: Wed, 19 Feb 2020 15:02:15 +0000	[thread overview]
Message-ID: <20200219150215.GU3466@techsingularity.net> (raw)
In-Reply-To: <20200211224719.29318.72113.stgit@localhost.localdomain>

On Tue, Feb 11, 2020 at 02:47:19PM -0800, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> In order to keep ourselves from reporting pages that are just going to be
> reused again in the case of heavy churn we can put a limit on how many
> total pages we will process per pass. Doing this will allow the worker
> thread to go into idle much more quickly so that we avoid competing with
> other threads that might be allocating or freeing pages.
> 
> The logic added here will limit the worker thread to no more than one
> sixteenth of the total free pages in a given area per list. Once that limit
> is reached it will update the state so that at the end of the pass we will
> reschedule the worker to try again in 2 seconds when the memory churn has
> hopefully settled down.
> 
> Again this optimization doesn't show much of a benefit in the standard case
> as the memory churn is minmal. However with page allocator shuffling
> enabled the gain is quite noticeable. Below are the results with a THP
> enabled version of the will-it-scale page_fault1 test showing the
> improvement in iterations for 16 processes or threads.
> 
> Without:
> tasks   processes       processes_idle  threads         threads_idle
> 16      8283274.75      0.17            5594261.00      38.15
> 
> With:
> tasks   processes       processes_idle  threads         threads_idle
> 16      8767010.50      0.21            5791312.75      36.98
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>

Seems fair. The test case you used would have been pounding on the zone
lock at fairly high frequency so it represents a worst-case scenario but
not necessarily an unrealistic one

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs

  reply	other threads:[~2020-02-19 15:02 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-11 22:45 [PATCH v17 0/9] mm / virtio: Provide support for free page reporting Alexander Duyck
2020-02-11 22:46 ` [PATCH v17 1/9] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2020-02-11 22:46 ` [PATCH v17 2/9] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2020-02-11 22:46 ` [PATCH v17 3/9] mm: Add function __putback_isolated_page Alexander Duyck
2020-02-19 14:33   ` Mel Gorman
2020-02-11 22:46 ` [PATCH v17 4/9] mm: Introduce Reported pages Alexander Duyck
2020-02-19 14:55   ` Mel Gorman
2020-02-20 18:44     ` Alexander Duyck
2020-02-20 22:35       ` Mel Gorman
2020-02-21 19:25         ` Alexander Duyck
2020-02-21 20:19           ` Mel Gorman
2020-02-11 22:46 ` [PATCH v17 5/9] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2020-02-11 22:46 ` [PATCH v17 6/9] virtio-balloon: Add support for providing free page reports to host Alexander Duyck
2020-02-11 22:47 ` [PATCH v17 7/9] mm/page_reporting: Rotate reported pages to the tail of the list Alexander Duyck
2020-02-19 14:59   ` Mel Gorman
2020-02-11 22:47 ` [PATCH v17 8/9] mm/page_reporting: Add budget limit on how many pages can be reported per pass Alexander Duyck
2020-02-19 15:02   ` Mel Gorman [this message]
2020-02-11 22:47 ` [PATCH v17 9/9] mm/page_reporting: Add free page reporting documentation Alexander Duyck
2020-02-11 22:51 ` [PATCH v17 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature Alexander Duyck
2020-02-11 22:51 ` [PATCH v17 QEMU 2/3] virtio-balloon: Add support for providing free page reports to host Alexander Duyck
2020-02-11 22:51 ` [PATCH v17 QEMU 3/3] virtio-balloon: Provide a interface for free page reporting Alexander Duyck
2020-02-11 22:53 ` [PATCH v17 QEMU 4/3 RFC] memory: Add support for MADV_FREE as mechanism to lazy discard pages Alexander Duyck
2020-02-11 23:05 ` [PATCH v17 0/9] mm / virtio: Provide support for free page reporting Andrew Morton
2020-02-11 23:55   ` Alexander Duyck
2020-02-12  0:19     ` Andrew Morton
2020-02-12  1:19       ` Alexander Duyck
2020-02-18 16:37       ` Alexander Duyck
2020-02-19  8:49         ` Mel Gorman
2020-02-19 15:06         ` Mel Gorman

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