From: "Li, Liang Z" <liang.z.li@intel.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
"Hansen, Dave" <dave.hansen@intel.com>,
David Hildenbrand <david@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"mhocko@suse.com" <mhocko@suse.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"dgilbert@redhat.com" <dgilbert@redhat.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>
Subject: RE: [Qemu-devel] [PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration
Date: Sat, 17 Dec 2016 11:56:40 +0000 [thread overview]
Message-ID: <F2CBF3009FA73547804AE4C663CAB28E3C32C4A1@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <20161216154049.GB6168@redhat.com>
> On Fri, Dec 16, 2016 at 01:12:21AM +0000, Li, Liang Z wrote:
> > There still exist the case if the MAX_ORDER is configured to a large
> > value, e.g. 36 for a system with huge amount of memory, then there is only
> 28 bits left for the pfn, which is not enough.
>
> Not related to the balloon but how would it help to set MAX_ORDER to 36?
>
My point here is MAX_ORDER may be configured to a big value.
> What the MAX_ORDER affects is that you won't be able to ask the kernel
> page allocator for contiguous memory bigger than 1<<(MAX_ORDER-1), but
> that's a driver issue not relevant to the amount of RAM. Drivers won't
> suddenly start to ask the kernel allocator to allocate compound pages at
> orders >= 11 just because more RAM was added.
>
> The higher the MAX_ORDER the slower the kernel runs simply so the smaller
> the MAX_ORDER the better.
>
> > Should we limit the MAX_ORDER? I don't think so.
>
> We shouldn't strictly depend on MAX_ORDER value but it's mostly limited
> already even if configurable at build time.
>
I didn't know that and will take a look, thanks for your information.
Liang
> We definitely need it to reach at least the hugepage size, then it's mostly
> driver issue, but drivers requiring large contiguous allocations should rely on
> CMA only or vmalloc if they only require it virtually contiguous, and not rely
> on larger MAX_ORDER that would slowdown all kernel allocations/freeing.
next prev parent reply other threads:[~2016-12-17 11:56 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-30 8:43 [PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration Liang Li
2016-11-30 8:43 ` [PATCH kernel v5 1/5] virtio-balloon: rework deflate to add page to a list Liang Li
2016-11-30 8:43 ` [PATCH kernel v5 2/5] virtio-balloon: define new feature bit and head struct Liang Li
2016-11-30 8:43 ` [PATCH kernel v5 3/5] virtio-balloon: speed up inflate/deflate process Liang Li
2016-11-30 8:43 ` [PATCH kernel v5 4/5] virtio-balloon: define flags and head for host request vq Liang Li
2016-11-30 8:43 ` [PATCH kernel v5 5/5] virtio-balloon: tell host vm's unused page info Liang Li
2016-11-30 19:15 ` Dave Hansen
2016-12-04 13:13 ` Li, Liang Z
2016-12-05 17:22 ` Dave Hansen
2016-12-06 4:47 ` Li, Liang Z
2016-12-06 8:40 ` [PATCH kernel v5 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration David Hildenbrand
2016-12-07 13:35 ` Li, Liang Z
2016-12-07 15:34 ` Dave Hansen
2016-12-09 3:09 ` Li, Liang Z
2016-12-07 15:42 ` David Hildenbrand
2016-12-07 15:45 ` Dave Hansen
2016-12-07 16:21 ` David Hildenbrand
2016-12-07 16:57 ` Dave Hansen
2016-12-07 18:38 ` [Qemu-devel] " Andrea Arcangeli
2016-12-07 18:44 ` Dave Hansen
2016-12-07 18:58 ` Andrea Arcangeli
2016-12-07 19:54 ` Dave Hansen
2016-12-07 20:28 ` Andrea Arcangeli
2016-12-09 4:45 ` Li, Liang Z
2016-12-09 4:53 ` Dave Hansen
2016-12-09 5:35 ` Li, Liang Z
2016-12-09 16:42 ` Andrea Arcangeli
2016-12-14 8:20 ` Li, Liang Z
2016-12-14 8:59 ` Li, Liang Z
2016-12-15 15:34 ` Dave Hansen
2016-12-15 15:54 ` Michael S. Tsirkin
2016-12-16 1:12 ` Li, Liang Z
2016-12-16 15:40 ` Andrea Arcangeli
2016-12-17 11:56 ` Li, Liang Z [this message]
2016-12-16 0:48 ` Li, Liang Z
2016-12-16 1:09 ` Dave Hansen
2016-12-16 1:38 ` Li, Liang Z
2016-12-16 1:40 ` Dave Hansen
2016-12-16 1:43 ` Li, Liang Z
2016-12-16 16:01 ` Andrea Arcangeli
2016-12-17 12:39 ` Li, Liang Z
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