From: Mel Gorman <firstname.lastname@example.org> To: David Hildenbrand <email@example.com> Cc: Alexander Duyck <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH v15 0/7] mm / virtio: Provide support for free page reporting Date: Fri, 13 Dec 2019 11:08:06 +0000 [thread overview] Message-ID: <20191213110806.GA3178@techsingularity.net> (raw) In-Reply-To: <firstname.lastname@example.org> On Fri, Dec 13, 2019 at 11:00:42AM +0100, David Hildenbrand wrote: > > A brief history on the background of free page reporting can be found at: > > https://email@example.com/ > > > > Changes from v13: > > https://firstname.lastname@example.org/ > > Rewrote core reporting functionality > > Merged patches 3 & 4 > > Dropped boundary list and related code > > Folded get_reported_page into page_reporting_fill > > Folded page_reporting_fill into page_reporting_cycle > > Pulled reporting functionality out of free_reported_page > > Renamed it to __free_isolated_page > > Moved page reporting specific bits to page_reporting_drain > > Renamed phdev to prdev since we aren't "hinting" we are "reporting" > > Added documentation to describe the usage of unused page reporting > > Updated cover page and patch descriptions to avoid mention of boundary > > > > Changes from v14: > > https://email@example.com/ > > Renamed "unused page reporting" to "free page reporting" > > Updated code, kconfig, and patch descriptions > > Split out patch for __free_isolated_page > > Renamed function to __putback_isolated_page > > Rewrote core reporting functionality > > Added logic to reschedule worker in 2 seconds instead of run to completion > > Removed reported_pages statistics > > Removed REPORTING_REQUESTED bit used in zone flags > > Replaced page_reporting_dev_info refcount with state variable > > Removed scatterlist from page_reporting_dev_info > > Removed capacity from page reporting device > > Added dynamic scatterlist allocation/free at start/end of reporting process > > Updated __free_one_page so that reported pages are not always added to tail > > Added logic to handle error from report function > > Updated virtio-balloon patch that adds support for page reporting > > Updated patch description to try and highlight differences in approaches > > Updated logic to reflect that we cannot limit the scatterlist from device > > Last time Mel said > > "Ok, I'm ok with how this hooks into the allocator as the overhead is > minimal. However, the patch itself still includes a number of > optimisations instead of being a bare-boned implementation of the > feature with optimisations layered on top." > I didn't get the chance to take a close look as I'm trying to clear as much as possible from my table on the run-up to Christmas so I don't come back to a disaster inbox. I also noted that the Acks for earlier patches were not included so I was uncertain if doing a full review would still be a good use of time when time was tight. That said, some optimisations are still included but much reduced. For example, list rotations are still there but it's very straight-forward. The refcount is gone which is good and replaced by a state, which could be be better documented, but is more straight forward and the zone->lock is back protecting the free lists primarily and not zone metadata or prdev metadata (at least not obviously). I didn't put in the time to see if the atomic_set in page_reporting_process() is ok or whether state could be lost but I *think* it's ok because it should be called from just one workqueue request and they shouldn't be stacked. A comment there explaining why atomic_set is definitely correct would be helpful. I'm inclined to decide that yes, this version is potentially ok as a bare minimum but didn't put in the time to be 100% sure. -- Mel Gorman SUSE Labs
next prev parent reply other threads:[~2019-12-13 20:36 UTC|newest] Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-05 16:22 Alexander Duyck 2019-12-05 16:22 ` [PATCH v15 1/7] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck 2019-12-05 16:22 ` [PATCH v15 2/7] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck 2019-12-05 16:22 ` [PATCH v15 3/7] mm: Add function __putback_isolated_page Alexander Duyck 2019-12-16 11:36 ` David Hildenbrand 2019-12-16 16:22 ` Alexander Duyck 2019-12-17 10:58 ` David Hildenbrand 2019-12-17 16:26 ` Alexander Duyck 2019-12-17 17:24 ` David Hildenbrand 2019-12-17 18:24 ` Alexander Duyck 2019-12-17 18:46 ` David Hildenbrand 2019-12-17 21:50 ` Alexander Duyck 2019-12-05 16:22 ` [PATCH v15 4/7] mm: Introduce Reported pages Alexander Duyck 2019-12-16 10:17 ` Nitesh Narayan Lal 2019-12-16 16:28 ` Alexander Duyck 2019-12-17 8:55 ` Nitesh Narayan Lal 2019-12-17 16:31 ` Alexander Duyck 2019-12-18 7:31 ` Mel Gorman 2019-12-16 11:44 ` Nitesh Narayan Lal 2019-12-16 16:10 ` Alexander Duyck 2019-12-05 16:22 ` [PATCH v15 5/7] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck 2019-12-13 7:03 ` Michael S. Tsirkin 2019-12-05 16:22 ` [PATCH v15 6/7] virtio-balloon: Add support for providing free page reports to host Alexander Duyck 2019-12-13 7:08 ` Michael S. Tsirkin 2019-12-13 16:35 ` Alexander Duyck 2019-12-15 9:29 ` Michael S. Tsirkin 2019-12-13 10:15 ` David Hildenbrand 2019-12-13 16:37 ` Alexander Duyck 2019-12-05 16:23 ` [PATCH v15 7/7] mm: Add free page reporting documentation Alexander Duyck 2019-12-05 16:24 ` [PATCH v15 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature Alexander Duyck 2019-12-05 16:24 ` [PATCH v15 QEMU 2/3] virtio-balloon: Add bit to notify guest of unused page reporting Alexander Duyck 2019-12-05 16:24 ` [PATCH v15 QEMU 3/3] virtio-balloon: Provide a interface for " Alexander Duyck 2019-12-05 16:26 ` [PATCH v15 QEMU 4/3 RFC] memory: Add support for MADV_FREE as mechanism to lazy discard pages Alexander Duyck 2019-12-12 23:47 ` [PATCH v15 0/7] mm / virtio: Provide support for free page reporting Alexander Duyck 2019-12-13 10:00 ` David Hildenbrand 2019-12-13 11:08 ` Mel Gorman [this message] 2019-12-13 16:59 ` Alexander Duyck 2019-12-13 16:46 ` Alexander Duyck 2019-12-16 12:21 ` David Hildenbrand
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