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From: "Denis V. Lunev" <den@openvz.org>
Message-ID: <56743443.5000907@openvz.org>
Date: Fri, 18 Dec 2015 19:28:51 +0300
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Subject: Re: [Qemu-devel] guest kernel in the host RAM
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>, QEMU <qemu-devel@nongnu.org>

On 12/15/2015 02:59 PM, Paolo Bonzini wrote:
>
> On 15/12/2015 12:27, Denis V. Lunev wrote:
>> The idea is that we could boot with the uncompressed Linux
>> kernel in the guest which serves 2 purposes:
>> - faster boot time as per Intel opinion
>> - memory savings
>>
>> Uncompressed kernel image could be the same for several
>> guests and thus memory pages for the kernel could be the
>> same, which saves a bit of RAM :)
>>
>> At the moment neither BIOS support this in full: nor SeaBIOS,
>> nor OVMF, nor QBoot.
>>
>>  From our point of view QBoot is an ideal candidate for this.
> QBoot is not meant for use in production; SeaBIOS actually is just as
> fast if you configure it right.
>
>> Do you have any opinion for the topic?
> I honestly don't like the idea.  Linux patches itself a lot, which
> makes the memory savings minimal (if they exist at all).  What is the
> decompression time for a kernel that is compressed with LZO?
>
> Paolo
It seems that you are perfectly correct here!

With large pages enabled (and preferred 2 Mb pages mode)
we will have exactly zero bonus.

Thank you for saving a lot of time and efforts :)))

Den