From: Michael Ellerman <michael@ellerman.id.au>
To: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, Anton Blanchard <anton@samba.org>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH v2] powerpc: align DTL buffer to AMS boundary
Date: Thu, 14 Apr 2011 14:12:43 +1000 [thread overview]
Message-ID: <1302754363.12513.89.camel@concordia> (raw)
In-Reply-To: <1302733988-23037-1-git-send-email-nacc@us.ibm.com>
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On Wed, 2011-04-13 at 15:33 -0700, Nishanth Aravamudan wrote:
> PAPR specifies that DTL buffers can not cross AMS environments (aka CMO
> in the PAPR) and can not cross a memory entitlement granule boundary
> (4k). This is found in section 14.11.3.2 H_REGISTER_VPA of the PAPR.
> kmalloc does not guarantee an alignment of the allocation, though,
> beyond 8 bytes (at least in my understanding). Over-allocate and align
> the resulting address.
You can specify alignment by creating your own kmem_cache, ie.
kmem_cache_create().
Obviously there will be some overhead to create the cache structure, but
I'd think it will be less than 4k * NR_CPUs.
cheers
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next prev parent reply other threads:[~2011-04-14 4:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-13 14:52 [PATCH] powerpc: align DTL buffer to AMS boundary Nishanth Aravamudan
2011-04-13 22:33 ` [PATCH v2] " Nishanth Aravamudan
2011-04-14 4:12 ` Michael Ellerman [this message]
2011-04-14 5:13 ` [PATCH v3] powerpc: use a kmem cache for DTL buffers Nishanth Aravamudan
2011-04-14 5:45 ` [PATCH v4] " Nishanth Aravamudan
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