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 1/2] mm: page_hinting: core infrastructure
Date: Thu, 11 Jul 2019 07:48:31 -0400 [thread overview]
Message-ID: <f41dfb69-5754-75a4-3eb0-1dda22b11b9c@redhat.com> (raw)
In-Reply-To: <3f9a7e7b-c026-3530-e985-804fc7f1ec31@intel.com>
On 7/10/19 4:45 PM, Dave Hansen wrote:
> On 7/10/19 12:51 PM, Nitesh Narayan Lal wrote:
>> +struct zone_free_area {
>> + unsigned long *bitmap;
>> + unsigned long base_pfn;
>> + unsigned long end_pfn;
>> + atomic_t free_pages;
>> + unsigned long nbits;
>> +} free_area[MAX_NR_ZONES];
> Why do we need an extra data structure. What's wrong with putting
> per-zone data in ... 'struct zone'? The cover letter claims that it
> doesn't touch core-mm infrastructure, but if it depends on mechanisms
> like this, I think that's a very bad thing.
>
> To be honest, I'm not sure this series is worth reviewing at this point.
> It's horribly lightly commented and full of kernel antipatterns lik
>
> void func()
> {
> if () {
> ... indent entire logic
> ... of function
> }
> }
>
> It has big "TODO"s. It's virtually comment-free. I'm shocked it's at
> the 11th version and still looking like this.
One of the reasons for being on v11 was that the entire design has
changed a few times.
But that's no excuse, I understand what you are saying and I will work
on it and improve this.
>
>> +
>> + for (zone_idx = 0; zone_idx < MAX_NR_ZONES; zone_idx++) {
>> + unsigned long pages = free_area[zone_idx].end_pfn -
>> + free_area[zone_idx].base_pfn;
>> + bitmap_size = (pages >> PAGE_HINTING_MIN_ORDER) + 1;
>> + if (!bitmap_size)
>> + continue;
>> + free_area[zone_idx].bitmap = bitmap_zalloc(bitmap_size,
>> + GFP_KERNEL);
> This doesn't support sparse zones. We can have zones with massive
> spanned page sizes, but very few present pages. On those zones, this
> will exhaust memory for no good reason.
Thanks, I will look into this.
>
> Comparing this to Alex's patch set, it's of much lower quality and at a
> much earlier stage of development. The two sets are not really even
> comparable right now. This certainly doesn't sell me on (or even really
> enumerate the deltas in) this approach vs. Alex's.
>
--
Thanks
Nitesh
next prev parent reply other threads:[~2019-07-11 11:48 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 [this message]
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
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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