Re: [Patch 0/7] Implement crashkernel=auto

From: Amerigo Wang <amwang@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Neil Horman <nhorman@redhat.com>,
	tony.luck@intel.com, linux-ia64@vger.kernel.org,
	Bernhard Walle <bernhard.walle@gmx.de>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
	Ingo Molnar <mingo@elte.hu>,
	Anton Vorontsov <avorontsov@ru.mvista.com>,
	akpm@linux-foundation.org
Subject: Re: [Patch 0/7] Implement crashkernel=auto
Date: Mon, 10 Aug 2009 11:11:34 +0800	[thread overview]
Message-ID: <4A7F8FE6.9030709@redhat.com> (raw)
In-Reply-To: <m1iqgze740.fsf@fess.ebiederm.org>

Eric W. Biederman wrote:
> Let me put this concrete proposal on the table.
>
> The problem:
>
> With the current set of crashkernel= options we are asking the
> distribution installer to perform magic.  Moving as much of this logic
> into a normal init script for better maintenance is desirable.
>
> My proposal:
>
> Implement crashkernel=max which reserves as much memory as is
> reasonable for a crash kernel, without seriously affecting stability,
> performance, and reliability.
>   

This is almost exactly what I want with crashkernel=auto....
So there's no big difference, except the name.

> As an initial approximation I would use a 32nd of low memory.
>   

Hmm, I think Bernhard's proposal is fine for this case, i.e. we can 
introduce a new syntax, "crashkernel=>>X" which means we reserve 1/2^X 
of system memory.

What do you think?

> In addition implement:
>
> /sys/kernel/crash_size
>
> That can be written to (with enough privileges when no crash kernel is
> loaded) reduce the amount of memory reserved by the crash kernel.
>   

Yeah, this is nice!

Thanks.

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