From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: Xen 4.3 + tmem = Xen BUG at domain_page.c:143
Date: Wed, 12 Jun 2013 18:26:44 +0100
Message-ID: <CDDE6DE4.54D3B%keir.xen@gmail.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
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On 12/06/2013 16:48, "Jan Beulich" <JBeulich@suse.com> wrote:

>> Why are we so tight on MAPCACHE_VCPU_ENTRIES? Why not say double that number
>> and get rid of the accum and the 'replace a hash entry instead' logic
>> instead? We never used to have it, and it's kind of extra complication and a
>> bit gross.
> 
> First of all, doubling the entries is not an argument for dropping
> that code - the old 32-bit implementation really would have
> needed this too from a theoretical perspective: The number of
> readily available (garbage) entries is bounded by
> MAPCACHE_VCPU_ENTRIES - MAPHASH_ENTRIES (because the
> hash entries actively block getting treated as garbage).

So? We have control over both MAPCACHE_VCPU_ENTRUES and MAPHASH_ENTRIES. We
can make these somewhat arbitrary constants big