From: Glauber Costa <glommer@parallels.com>
To: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@suse.cz>,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] slab: Ignore internal flags in cache creation
Date: Fri, 28 Sep 2012 11:46:49 +0400 [thread overview]
Message-ID: <506555E9.2030809@parallels.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1209271552350.13360@chino.kir.corp.google.com>
On 09/28/2012 02:56 AM, David Rientjes wrote:
> On Thu, 27 Sep 2012, Glauber Costa wrote:
>
>> But I still don't see the big reason for your objection. If other
>> allocator start using those bits, they would not be passed to
>> kmem_cache_alloc anyway, right? So what would be the big problem in
>> masking them out before it?
>>
>
> A slab allocator implementation may allow for additional bits that are
> currently not used or used for internal purposes by the current set of
> slab allocators to be passed in the unsigned long to kmem_cache_create()
> that would be a no-op on other allocators. It's implementation defined,
> so this masking should be done in the implementation, i.e.
> __kmem_cache_create().
>
> For context, as many people who attended the kernel summit and LinuxCon
> are aware, a new slab allocator is going to be proposed soon that actually
> uses additional bits that aren't defined for all slab allocators. My
> opinion is that leaving unused bits and reserved bits to the
> implementation is the best software engineering practice.
>
I am happy as long as we don't BUG and can mask out that feature.
If Christoph is happy with me masking it in the SLAB only, I'm also fine.
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next prev parent reply other threads:[~2012-09-28 7:50 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-25 11:17 [PATCH] slab: Ignore internal flags in cache creation Glauber Costa
2012-09-25 16:26 ` Christoph Lameter
2012-09-26 0:46 ` David Rientjes
2012-09-26 8:43 ` Glauber Costa
2012-09-27 1:16 ` David Rientjes
2012-09-27 6:59 ` Glauber Costa
2012-09-27 22:56 ` David Rientjes
2012-09-28 7:46 ` Glauber Costa [this message]
2012-09-28 20:25 ` David Rientjes
2012-09-28 14:12 ` Christoph Lameter
2012-09-28 20:39 ` David Rientjes
2012-09-28 21:20 ` Christoph Lameter
2012-09-28 23:11 ` David Rientjes
2012-10-01 17:54 ` Christoph Lameter
2012-10-01 7:28 ` Pekka Enberg
2012-10-01 7:58 ` Glauber Costa
2012-09-27 13:54 ` Christoph Lameter
2012-09-27 22:50 ` David Rientjes
2012-09-28 14:04 ` Christoph Lameter
2012-09-28 20:36 ` David Rientjes
2012-09-26 14:57 ` Christoph Lameter
2012-09-27 1:12 ` David Rientjes
2012-09-27 13:57 ` Christoph Lameter
2012-09-27 22:52 ` David Rientjes
2012-09-28 14:10 ` Christoph Lameter
2012-09-28 20:30 ` David Rientjes
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