Message-ID: <52D6C4B6.8010804@zytor.com>
Date: Wed, 15 Jan 2014 09:26:14 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Vivek Goyal <vgoyal@redhat.com>,
        HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
CC: hpa@linux.intel.com, jingbai.ma@hp.com, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org, bp@alien8.de, ebiederm@xmission.com,
        akpm@linux-foundation.org, fengguang.wu@intel.com
Subject: Re: [RESEND PATCH v10] x86, apic, kexec, Documentation: Add disable_cpu_apicid
 kernel parameter
References: <20140115064458.1545.38775.stgit@localhost6.localdomain6> <20140115170525.GF3180@redhat.com>
In-Reply-To: <20140115170525.GF3180@redhat.com>
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On 01/15/2014 09:05 AM, Vivek Goyal wrote:
> 
> I think this is a reasonable approach to solve the issue. Use a command
> line to not bring up specific cpu in second kernel which can create
> problems.
> 
> Acked-by: Vivek Goyal <vgoyal@redhat.com>
> 
> hpa, I know you are not excited about this approach. If you made up your
> mind that this appoarch is not worth pursuing, please do suggest what
> would you like to see and we can give that a try.
> 
> We want to solve this problem as on large memory machines saving dump can
> take lot of time and we want to bring up multiple cpus and speed up
> compression and save on dump time.
> 

I'm not excited about kdump's reliance on the command line, since it
seems to be a neverending source of trouble, simply because the command
line is fundamentally intended as a human interface.  However, this
seems relatively harmless in comparison with everything else and I am
much happier with saving the ID in the first kernel rather than trying
to guess if a currently-downed CPU is the BSP.

	-hpa

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