linux-kernel - RE: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option

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Message-ID: <E86EADE93E2D054CBCD4E708C38D364A54299720@G01JPEXMBYT01>
Date:	Thu, 10 Dec 2015 05:37:41 +0000
From:	"Izumi, Taku" <izumi.taku@...fujitsu.com>
To:	Xishi Qiu <qiuxishi@...wei.com>, "Luck, Tony" <tony.luck@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"Kamezawa, Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"mel@....ul.ie" <mel@....ul.ie>,
	"Hansen, Dave" <dave.hansen@...el.com>,
	"matt@...eblueprint.co.uk" <matt@...eblueprint.co.uk>
Subject: RE: [PATCH v3 2/2] mm: Introduce kernelcore=mirror option

Dear Tony, Xishi,

> >> How about add some comment, if mirrored memroy is too small, then the
> >> normal zone is small, so it may be oom.
> >> The mirrored memory is at least 1/64 of whole memory, because struct
> >> pages usually take 64 bytes per page.
> >
> > 1/64th is the absolute lower bound (for the page structures as you say). I
> > expect people will need to configure 10% or more to run any real workloads.

> >
> > I made the memblock boot time allocator fall back to non-mirrored memory
> > if mirrored memory ran out.  What happens in the run time allocator if the
> > non-movable zones run out of pages? Will we allocate kernel pages from movable
> > memory?
> >
> 
> As I know, the kernel pages will not allocated from movable zone.

 Yes, kernel pages are not allocated from ZONE_MOVABLE.

 In this case administrator must review and reconfigure the mirror ratio via 
 "MirrorRequest" EFI variable.
 
  Sincerely,
  Taku Izumi

>
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> 
> 

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