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From: David Miller <davem@davemloft.net>
To: jane.chu@oracle.com
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: Mon, 05 Jun 2017 23:27:24 -0400 (EDT)	[thread overview]
Message-ID: <20170605.232724.386554178947981058.davem@davemloft.net> (raw)
In-Reply-To: <6255d34e-499d-db38-ec86-8930828684de@oracle.com>

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.

Thank you.

  reply	other threads:[~2017-06-06  3:27 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 [this message]
2017-06-06 17:04       ` jane.chu

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