From: Benjamin Herrenschmidt <benh@au1.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
linuxppc-dev@lists.ozlabs.org
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH kernel] powerpc/powernv/ioda2: Gracefully fail if too many TCE levels requested
Date: Mon, 06 Mar 2017 10:03:54 +1100 [thread overview]
Message-ID: <1488755034.2870.114.camel@au1.ibm.com> (raw)
In-Reply-To: <87innvrj9h.fsf@concordia.ellerman.id.au>
On Mon, 2017-02-27 at 22:00 +1100, Michael Ellerman wrote:
> > The alternative would be allocating TCE tables as big as PAGE_SIZE
> > but
> > only using parts of it but this would complicate a bit bits of code
> > responsible for overall amount of memory used for TCE table.
> >
> > Or kmem_cache_create() could be used to allocate as big TCE table
> > levels
> > as we really need but that API does not seem to support NUMA nodes.
>
> kmem_cache_alloc_node() ?
Is that 55 bits of address space (ie, 3 indirect levels + 64k pages) ?
Or only 39 (2 indirect level + 64k pages) ?
In the former case, I'm happy to limit the levels to 3 for 64K pages,
55 bits of TCE space is more than enough. 39 isn't however.
Cheers,
Ben.
next prev parent reply other threads:[~2017-03-05 23:05 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-22 4:43 [PATCH kernel] powerpc/powernv/ioda2: Gracefully fail if too many TCE levels requested Alexey Kardashevskiy
2017-02-27 0:53 ` Gavin Shan
2017-02-27 11:00 ` Michael Ellerman
2017-02-28 0:54 ` Alexey Kardashevskiy
2017-03-05 23:03 ` Benjamin Herrenschmidt [this message]
2017-03-06 1:28 ` Alexey Kardashevskiy
2017-03-06 3:36 ` Benjamin Herrenschmidt
2017-03-06 4:02 ` Alexey Kardashevskiy
2017-03-14 11:45 ` [kernel] " Michael Ellerman
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