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From: jane.chu@oracle.com
To: David Miller <davem@davemloft.net>
Cc: tglx@linutronix.de, atish.patra@oracle.com,
	Liam.Howlett@oracle.com, sparclinux@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
Date: Tue, 6 Jun 2017 10:04:25 -0700	[thread overview]
Message-ID: <c0b19f67-db79-c171-6f5b-6ecd1ec42078@oracle.com> (raw)
In-Reply-To: <20170605.232724.386554178947981058.davem@davemloft.net>

On 06/05/2017 08:27 PM, David Miller wrote:

> From: jane.chu@oracle.com
> Date: Mon, 5 Jun 2017 20:03:28 -0700
>
>> On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up
>> allocating from kmalloc_caches[6] - a 64-byte kmem-cache allocated
>> by kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
>> l3-cache-line-size alignment, i.e. 64byte.  I printed out the
>> 'mondo' pa and verified that.
> Please check this, because that is an implementation detail.  We have
> three SLAB allocators.
>
> For example, if the user enables SLOB, I bet you don't get that
> alignment.
>
> The only thing we are universally guaranteed is ARCH_KMALLOC_MINALIGN.
>
> Please implement this properly, rather than relying upon things like
> the above.

Good point, agreed.  I will update the patch.

thanks!
-jane

>
> Thank you.

      reply	other threads:[~2017-06-06 17:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-05 22:48 Jane Chu
2017-06-06  0:57 ` David Miller
2017-06-06  3:03   ` jane.chu
2017-06-06  3:27     ` David Miller
2017-06-06 17:04       ` jane.chu [this message]

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