From: Nitesh Narayan Lal <nitesh@redhat.com> To: Alexander Duyck <alexander.h.duyck@linux.intel.com>, Alexander Duyck <alexander.duyck@gmail.com>, kvm@vger.kernel.org, mst@redhat.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz Cc: yang.zhang.wz@gmail.com, konrad.wilk@oracle.com, david@redhat.com, pagupta@redhat.com, riel@surriel.com, lcapitulino@redhat.com, dave.hansen@intel.com, wei.w.wang@intel.com, aarcange@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, osalvador@suse.de Subject: Re: [PATCH v15 4/7] mm: Introduce Reported pages Date: Tue, 17 Dec 2019 03:55:49 -0500 [thread overview] Message-ID: <06ca452e-90b3-c1b5-f2c0-e8da2444bcfe@redhat.com> (raw) In-Reply-To: <537e970f062e0c7f89723f63fc1f3ec6e53614a5.camel@linux.intel.com> On 12/16/19 11:28 AM, Alexander Duyck wrote: > On Mon, 2019-12-16 at 05:17 -0500, Nitesh Narayan Lal wrote: >> On 12/5/19 11:22 AM, Alexander Duyck wrote: >>> From: Alexander Duyck <alexander.h.duyck@linux.intel.com> >>> >>> In order to pave the way for free page reporting in virtualized >>> environments we will need a way to get pages out of the free lists and >>> identify those pages after they have been returned. To accomplish this, >>> this patch adds the concept of a Reported Buddy, which is essentially >>> meant to just be the Uptodate flag used in conjunction with the Buddy >>> page type. >> [...] >> >>> +enum { >>> + PAGE_REPORTING_IDLE = 0, >>> + PAGE_REPORTING_REQUESTED, >>> + PAGE_REPORTING_ACTIVE >>> +}; >>> + >>> +/* request page reporting */ >>> +static void >>> +__page_reporting_request(struct page_reporting_dev_info *prdev) >>> +{ >>> + unsigned int state; >>> + >>> + /* Check to see if we are in desired state */ >>> + state = atomic_read(&prdev->state); >>> + if (state == PAGE_REPORTING_REQUESTED) >>> + return; >>> + >>> + /* >>> + * If reporting is already active there is nothing we need to do. >>> + * Test against 0 as that represents PAGE_REPORTING_IDLE. >>> + */ >>> + state = atomic_xchg(&prdev->state, PAGE_REPORTING_REQUESTED); >>> + if (state != PAGE_REPORTING_IDLE) >>> + return; >>> + >>> + /* >>> + * Delay the start of work to allow a sizable queue to build. For >>> + * now we are limiting this to running no more than once every >>> + * couple of seconds. >>> + */ >>> + schedule_delayed_work(&prdev->work, PAGE_REPORTING_DELAY); >>> +} >>> + >> I think you recently switched to using an atomic variable for maintaining page >> reporting status as I was doing in v12. >> Which is good, as we will not have a disagreement on it now. > There is still some differences between our approaches if I am not > mistaken. Specifically I have code in place so that any requests to report > while we are actively working on reporting will trigger another pass being > scheduled after we completed. I still believe you were lacking any logic > like that as I recall. > Yes, I was specifically referring to the atomic state variable. Though I am wondering if having an atomic variable to track page reporting state is better than having a page reporting specific unsigned long flag, which we can manipulate via __set_bit() and __clear_bit(). >> On a side note, apologies for not getting involved actively in the >> discussions/reviews as I am on PTO. > No problem. I've been mostly looking for input from the core MM > maintainers anyway as we sorted most of the virtualization pieces some > time ago. > -- Thanks Nitesh
next prev parent reply other threads:[~2019-12-17 8:56 UTC|newest] Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-05 16:22 [PATCH v15 0/7] mm / virtio: Provide support for free page reporting 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 [this message] 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 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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