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[Xen-devel] Re: [PATCH] less verbose tmem, was: tmem_relinquish_page: fa

To: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] less verbose tmem, was: tmem_relinquish_page: failing order=<n>
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 07 Jan 2010 15:07:20 +0000
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>>> Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> 06.01.10 18:13 >>>
>The message is relevant if any code calling alloc_heap_pages()
>for order>0 isn't able to fallback to order=0.  All usages today
>in Xen can fallback, but future calls may not, so I'd prefer
>to keep the printk there at least in xen-unstable.  BUT there's

What makes you think so? Iirc there are several xmalloc()-s of more
than a page in size (which ultimately will call alloc_heap_pages()),
and those usually don't have a fallback.

>no reason for the message to be logged in a released Xen
>so here's a patch to ifndef NDEBUG the printk.

Even in a debug build this may be really annoying: On NUMA machines,
the dma_bitsize mechanism (to avoid exhausting DMA memory) can
cause close to 2000 of these messages when allocating Dom0's
initial memory (in the absence of a severely restricting dom0_mem,
and with node 0 spanning 4G or more). This makes booting
unacceptably slow, especially when using a graphical console mode.


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