Subject: Re: [PATCH] x86/boot: Support uncompressed kernel
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Chao Peng <chao.p.peng@linux.intel.com>
References: <1490273467-97948-1-git-send-email-chao.p.peng@linux.intel.com>
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Cc: 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>,
        Arnd Bergmann <arnd@arndb.de>, 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>
From: Michal Marek <mmarek@suse.com>
Message-ID: <2e97b35f-bb9e-66e4-736d-66313626354e@suse.com>
Date: Mon, 27 Mar 2017 13:47:39 +0200
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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.

Michal