From: David Hildenbrand <david@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
Alexander Duyck <alexander.duyck@gmail.com>
Cc: virtio-dev@lists.oasis-open.org, kvm list <kvm@vger.kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@kernel.org>, linux-mm <linux-mm@kvack.org>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
linux-arm-kernel@lists.infradead.org,
Oscar Salvador <osalvador@suse.de>,
Yang Zhang <yang.zhang.wz@gmail.com>,
Pankaj Gupta <pagupta@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Nitesh Narayan Lal <nitesh@redhat.com>,
Rik van Riel <riel@surriel.com>,
lcapitulino@redhat.com, "Wang, Wei W" <wei.w.wang@intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>
Subject: Re: [PATCH v10 3/6] mm: Introduce Reported pages
Date: Mon, 23 Sep 2019 17:47:24 +0200 [thread overview]
Message-ID: <49395e48-175f-8483-77f5-5fc3aca8b7cb@redhat.com> (raw)
In-Reply-To: <baf3dd5c-9368-d621-a83a-114bb5ae8291@redhat.com>
On 23.09.19 17:45, David Hildenbrand wrote:
> On 23.09.19 17:37, Michael S. Tsirkin wrote:
>> On Mon, Sep 23, 2019 at 08:28:00AM -0700, Alexander Duyck wrote:
>>> On Mon, Sep 23, 2019 at 8:00 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>>>>
>>>> On Mon, Sep 23, 2019 at 07:50:15AM -0700, Alexander Duyck wrote:
>>>>>>> +static inline void
>>>>>>> +page_reporting_reset_boundary(struct zone *zone, unsigned int order, int mt)
>>>>>>> +{
>>>>>>> + int index;
>>>>>>> +
>>>>>>> + if (order < PAGE_REPORTING_MIN_ORDER)
>>>>>>> + return;
>>>>>>> + if (!test_bit(ZONE_PAGE_REPORTING_ACTIVE, &zone->flags))
>>>>>>> + return;
>>>>>>> +
>>>>>>> + index = get_reporting_index(order, mt);
>>>>>>> + reported_boundary[index] = &zone->free_area[order].free_list[mt];
>>>>>>> +}
>>>>>>
>>>>>> So this seems to be costly.
>>>>>> I'm guessing it's the access to flags:
>>>>>>
>>>>>>
>>>>>> /* zone flags, see below */
>>>>>> unsigned long flags;
>>>>>>
>>>>>> /* Primarily protects free_area */
>>>>>> spinlock_t lock;
>>>>>>
>>>>>>
>>>>>>
>>>>>> which is in the same cache line as the lock.
>>>>>
>>>>> I'm not sure what you mean by this being costly?
>>>>
>>>> I've just been wondering why does will it scale report a 1.5% regression
>>>> with this patch.
>>>
>>> Are you talking about data you have collected from a test you have
>>> run, or the data I have run?
>>
>> About the kernel test robot auto report that was sent recently.
>
> https://lkml.org/lkml/2019/9/21/112
>
> And if I'm correct, that regression is observable in case reporting is
> not enabled. (so with this patch applied only, e.g., on a bare-metal system)
>
To be even more precise: # CONFIG_PAGE_REPORTING is not set
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2019-09-23 15:47 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-18 17:52 [PATCH v10 0/6] mm / virtio: Provide support for unused page reporting 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 [this message]
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
2019-09-24 15:51 ` Nitesh Narayan Lal
2019-09-24 17:07 ` Alexander Duyck
2019-09-24 17:28 ` David Hildenbrand
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