Messages in this thread | | | From | Cong Wang <> | Subject | Re: [PATCH 0/2] kdump: Enter 2nd kernel with BSP for enabling multiple CPUs | Date | Mon, 14 May 2012 08:29:08 +0000 (UTC) |
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So, the reason why you want to have multiple CPU's enabled in the 2nd kernel is to speed up the compression of the core dump?
The first question is that, why the speed is important? Given the fact that the whole kdump progress happens automatically nowdays, there should be very few guys waiting for a kdump to complete, so the speed is not that important.
Second, currently we use nr_cpus=1 for the 2nd kernel on RHEL6, to reduce the memory usage in the 2nd kernel. You mentioned 512M is a limit, but we want to make it even less, even 512M is not a good choice for us on x86. Bringing up more than 1 CPU will of course need more memory in the 2nd kernel.
The limit is not only the size, but also the max address of loading initrd, which is 896M on x86 IIRC. A contiguos memory area larger than 512M usually sit above 869M, due to the fragmentation in the lower memory, so I am afraid you need to do (much?) more work.
So, I am afraid you spend too much effort to fix a not-that-important issue, but I may miss something here...
Thanks.
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