From: Nitesh Narayan Lal <nitesh@redhat.com>
To: Dave Hansen <dave.hansen@intel.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, pbonzini@redhat.com, lcapitulino@redhat.com,
pagupta@redhat.com, wei.w.wang@intel.com,
yang.zhang.wz@gmail.com, riel@surriel.com, david@redhat.com,
mst@redhat.com, dodgen@google.com, konrad.wilk@oracle.com,
dhildenb@redhat.com, aarcange@redhat.com,
alexander.duyck@gmail.com, john.starks@microsoft.com,
mhocko@suse.com
Subject: Re: [RFC][PATCH v11 0/2] mm: Support for page hinting
Date: Thu, 11 Jul 2019 07:37:49 -0400 [thread overview]
Message-ID: <f781e5db-cfed-6acf-c844-4825f2336567@redhat.com> (raw)
In-Reply-To: <b6da49e4-5007-08f9-104a-aeca5dca4719@intel.com>
On 7/10/19 4:19 PM, Dave Hansen wrote:
> On 7/10/19 12:51 PM, Nitesh Narayan Lal wrote:
>> This patch series proposes an efficient mechanism for reporting free memory
>> from a guest to its hypervisor. It especially enables guests with no page cache
>> (e.g., nvdimm, virtio-pmem) or with small page caches (e.g., ram > disk) to
>> rapidly hand back free memory to the hypervisor.
>> This approach has a minimal impact on the existing core-mm infrastructure.
>>
>> Measurement results (measurement details appended to this email):
>> *Number of 5GB guests (each touching 4GB memory) that can be launched
>> without swap usage on a system with 15GB:
> This sounds like a reasonable measurement, but I think you're missing a
> sentence or two explaining why this test was used.
I will re-work the cover email to better communicate the numbers.
>
>> unmodified kernel - 2, 3rd with 2.5GB
> What does "3rd with 2.5GB" mean? The third gets 2.5GB before failing an
> allocation and crashing?
It doesn't crash or fail. To complete the execution of the test
application which allocates 4GB memory in the 3rd guest 2.5GB swap has
been accessed.
>
>> v11 page hinting - 6, 7th with 26MB
>> v1 bubble hinting[1] - 6, 7th with 1.8GB (bubble hinting is another series
>> proposed to solve the same problems)
> Could you please make an effort to format things so that reviewers can
> easily read them? Aligning columns and using common units would be very
> helpful, for instance:
>
> unmodified kernel - 2, 3rd with 2.50 GB
> v11 page hinting - 6, 7th with 0.03 GB
> v1 bubble hinting[1] - 6, 7th with 1.80 GB
>
> See how you can scan that easily and compare between the rows?
>
> I think you did some analysis below. But, that seems misplaced. It's
> better to include the conclusion here and the details to back it up
> later. As it stands, the cover letter just throws some data at a
> reviewer and hopes they can make sense of it.
I will improve this. Thanks.
>
>> *Memhog execution time (For 3 guests each of 6GB on a system with 15GB):
>> unmodified kernel - Guest1:21s, Guest2:27s, Guest3:2m37s swap used = 3.7GB
>> v11 page hinting - Guest1:23s, Guest2:26s, Guest3:21s swap used = 0
>> v1 bubble hinting - Guest1:23, Guest2:11s, Guest3:26s swap used = 0
> Again, I'm finding myself having to reformat your data just so I can
> make sense of it. You also forgot the unit for Guest 1 in row 3.
>
> unmodified - Guest1:21s, Guest2:27s, Guest3:2m37s swap used = 3.7GB
>
> v11 hinting - Guest1:23s, Guest2:26s, Guest3:21s swap used = 0
> v1 bubble - Guest1:23s, Guest2:11s, Guest3:26s swap used = 0
>
> So, what is this supposed to show? What does it mean? Why do the
> numbers vary *so* much?
Basically, the idea was to communicate that with hinting swap was not
accessed and hence the time of execution is lower.
But as you already mentioned next time around I will format this and add
the conclusion along with these numbers.
I agree with Alexander's comment that there is no point of having the
same thing at two place.
--
Thanks
Nitesh
next prev parent reply other threads:[~2019-07-11 11:38 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-10 19:51 [RFC][PATCH v11 0/2] mm: Support for page hinting Nitesh Narayan Lal
2019-07-10 19:51 ` [RFC][Patch v11 1/2] mm: page_hinting: core infrastructure Nitesh Narayan Lal
2019-07-10 20:45 ` Dave Hansen
2019-07-11 11:48 ` Nitesh Narayan Lal
2019-07-11 15:25 ` Nitesh Narayan Lal
2019-07-11 15:50 ` Nitesh Narayan Lal
2019-07-11 16:22 ` Dave Hansen
2019-07-11 16:36 ` Nitesh Narayan Lal
2019-07-11 16:45 ` Dave Hansen
2019-07-11 16:52 ` Nitesh Narayan Lal
2019-07-15 9:26 ` David Hildenbrand
2019-07-10 21:56 ` Alexander Duyck
2019-07-11 17:58 ` Nitesh Narayan Lal
2019-07-11 23:20 ` Alexander Duyck
2019-07-12 1:12 ` Nitesh Narayan Lal
2019-07-12 16:22 ` Alexander Duyck
2019-07-12 16:25 ` Nitesh Narayan Lal
2019-08-08 11:41 ` Nitesh Narayan Lal
2019-07-11 18:21 ` Dave Hansen
2019-07-15 9:33 ` David Hildenbrand
2019-07-15 14:40 ` David Hildenbrand
2019-07-10 19:51 ` [RFC][Patch v11 2/2] virtio-balloon: page_hinting: reporting to the host Nitesh Narayan Lal
2019-07-24 19:47 ` Michael S. Tsirkin
2019-07-24 19:56 ` David Hildenbrand
2019-07-24 20:10 ` Nitesh Narayan Lal
2019-07-24 20:06 ` Nitesh Narayan Lal
2019-07-10 19:53 ` [QEMU Patch] virtio-baloon: Support for page hinting Nitesh Narayan Lal
2019-07-10 20:17 ` Alexander Duyck
2019-07-11 12:03 ` Nitesh Narayan Lal
2019-07-11 8:49 ` Cornelia Huck
2019-07-11 11:13 ` Nitesh Narayan Lal
2019-07-11 18:55 ` Michael S. Tsirkin
2019-07-11 19:06 ` Nitesh Narayan Lal
2019-07-11 22:36 ` Alexander Duyck
2019-07-10 20:19 ` [RFC][PATCH v11 0/2] mm: " Dave Hansen
2019-07-11 11:37 ` Nitesh Narayan Lal [this message]
2019-07-10 23:40 ` Alexander Duyck
2019-07-11 11:30 ` Nitesh Narayan Lal
2019-07-11 14:58 ` Alexander Duyck
2019-07-11 15:03 ` Nitesh Narayan Lal
2019-07-11 15:08 ` Alexander Duyck
2019-07-11 15:19 ` Nitesh Narayan Lal
2019-07-11 17:01 ` Alexander Duyck
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