Re: [PATCH] x86/boot: Support uncompressed kernel

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From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86/boot: Support uncompressed kernel
Date	Mon, 27 Mar 2017 15:30:01 +0200
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X-Original-Cc	Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Chao Peng <chao.p.peng@linux.intel.com>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, Yinghai Lu <yinghai@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "the arch/x86 maintainers" <x86@kernel.org>, Kees Cook <keescook@chromium.org>, Baoquan He <bhe@redhat.com>, "H.J. Lu" <hjl.tools@gmail.com>, Paul Bolle <pebolle@tiscali.nl>, Masahiro Yamada <yamada.masahiro@socionext.com>, Borislav Petkov <bp@suse.de>, Andrew Morton <akpm@linux-foundation.org>, Petr Mladek <pmladek@suse.com>, "David S. Miller" <davem@davemloft.net>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Andy Lutomirski <luto@kernel.org>, Thomas Garnier <thgarnie@google.com>, Nicolas Pitre <nicolas.pitre@linaro.org>, Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>, Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-kbuild <linux-kbuild@vger.kernel.org>
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On Mon, Mar 27, 2017 at 1:47 PM, Michal Marek <mmarek@suse.com> wrote:
> Dne 27.3.2017 v 09:58 Sebastian Andrzej Siewior napsal(a):
>> On 2017-03-24 13:35:40 [+0800], Chao Peng wrote:
>>>
>>>>>>     kernel               kernel size    time in decompress_kernel
>>>>>>     compressed (gzip)    3.3M           53ms
>>>>>>     uncompressed         14M            3ms
>>>>>
>>> Exactly, LZ4 is the fastest. It takes 16ms to complete the
>>> decompression. Still sounds a little longer when compared to
>>> uncompressed kernel.
>>
>> Are we seriously talking here about one-time improvement of 13ms
>> boot time?
>
> If the use case is launching new VM instances continuously, then
> compressing the kernel image is about as useful as compressing /bin/bash.

I guess the next step would be to use CONFIG_XIP_KERNEL on x86,
which requires an uncompressed kernel but has the additional advantage
of sharing the read-only sections of the kernel image across virtual
machines, resulting in better RAM and cache usage.

        Arnd

Thread

[PATCH] x86/boot: Support uncompressed kernel Chao Peng <chao.p.peng@linux.intel.com> - 2017-03-23 14:10 +0100
  Re: [PATCH] x86/boot: Support uncompressed kernel Yinghai Lu <yinghai@kernel.org> - 2017-03-23 16:10 +0100
    Re: [PATCH] x86/boot: Support uncompressed kernel Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-23 16:40 +0100
      Re: [PATCH] x86/boot: Support uncompressed kernel Chao Peng <chao.p.peng@linux.intel.com> - 2017-03-24 06:40 +0100
        Re: [PATCH] x86/boot: Support uncompressed kernel Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2017-03-27 10:10 +0200
          Re: [PATCH] x86/boot: Support uncompressed kernel Chao Peng <chao.p.peng@linux.intel.com> - 2017-03-27 11:30 +0200
          Re: [PATCH] x86/boot: Support uncompressed kernel Michal Marek <mmarek@suse.com> - 2017-03-27 14:00 +0200
            Re: [PATCH] x86/boot: Support uncompressed kernel Arnd Bergmann <arnd@arndb.de> - 2017-03-27 15:30 +0200
              Re: [PATCH] x86/boot: Support uncompressed kernel Chao Peng <chao.p.peng@linux.intel.com> - 2017-03-28 14:10 +0200
                Re: [PATCH] x86/boot: Support uncompressed kernel "H. Peter Anvin" <hpa@zytor.com> - 2017-03-29 01:00 +0200
                Re: [PATCH] x86/boot: Support uncompressed kernel Andy Lutomirski <luto@amacapital.net> - 2017-03-29 01:00 +0200
  Re: [PATCH] x86/boot: Support uncompressed kernel Michal Marek <mmarek@suse.com> - 2017-03-24 09:30 +0100

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