From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Timur Tabi <timur@freescale.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andi Kleen <andi@firstfloor.org>, Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Nazarewicz <mina86@mina86.com>,
David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 2/3] make new alloc_pages_exact()
Date: Thu, 28 Apr 2011 09:02:57 -0700 [thread overview]
Message-ID: <1304006577.9516.2578.camel@nimitz> (raw)
In-Reply-To: <4DB88DAF.2010504@freescale.com>
On Wed, 2011-04-27 at 16:42 -0500, Timur Tabi wrote:
> Dave Hansen wrote:
> >> Is there an easy way to verify that alloc_pages_exact(5MB) really does allocate
> >> > only 5MB and not 8MB?
>
> > I'm not sure why you're asking. How do we know that the _normal_
> > allocator only gives us 4k when we ask for 4k? Well, that's just how it
> > works. If alloc_pages_exact() returns success, you know it's got the
> > amount of memory that you asked for, and only that plus a bit of masking
> > for page alignment.
> >
> > Have you seen alloc_pages_exact() behaving in some other way?
>
> I've never tested this part of alloc_pages_exact(), even when I wrote (the first
> version of) it. I just took it on faith that it actually did what it was
> supposed to do.
I did actually go add a bunch of printks to it at one point. It did
seem to be working just fine and freeing the right amount of memory.
-- Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Timur Tabi <timur@freescale.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andi Kleen <andi@firstfloor.org>, Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Nazarewicz <mina86@mina86.com>,
David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 2/3] make new alloc_pages_exact()
Date: Thu, 28 Apr 2011 09:02:57 -0700 [thread overview]
Message-ID: <1304006577.9516.2578.camel@nimitz> (raw)
In-Reply-To: <4DB88DAF.2010504@freescale.com>
On Wed, 2011-04-27 at 16:42 -0500, Timur Tabi wrote:
> Dave Hansen wrote:
> >> Is there an easy way to verify that alloc_pages_exact(5MB) really does allocate
> >> > only 5MB and not 8MB?
>
> > I'm not sure why you're asking. How do we know that the _normal_
> > allocator only gives us 4k when we ask for 4k? Well, that's just how it
> > works. If alloc_pages_exact() returns success, you know it's got the
> > amount of memory that you asked for, and only that plus a bit of masking
> > for page alignment.
> >
> > Have you seen alloc_pages_exact() behaving in some other way?
>
> I've never tested this part of alloc_pages_exact(), even when I wrote (the first
> version of) it. I just took it on faith that it actually did what it was
> supposed to do.
I did actually go add a bunch of printks to it at one point. It did
seem to be working just fine and freeing the right amount of memory.
-- Dave
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next prev parent reply other threads:[~2011-04-28 16:03 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-14 20:01 [PATCH 1/3] rename alloc_pages_exact() Dave Hansen
2011-04-14 20:01 ` Dave Hansen
2011-04-14 20:01 ` [PATCH 2/3] make new alloc_pages_exact() Dave Hansen
2011-04-14 20:01 ` Dave Hansen
2011-04-14 21:55 ` David Rientjes
2011-04-14 21:55 ` David Rientjes
2011-04-27 21:30 ` Timur Tabi
2011-04-27 21:30 ` Timur Tabi
2011-04-27 21:37 ` Dave Hansen
2011-04-27 21:37 ` Dave Hansen
2011-04-27 21:42 ` Timur Tabi
2011-04-27 21:42 ` Timur Tabi
2011-04-28 16:02 ` Dave Hansen [this message]
2011-04-28 16:02 ` Dave Hansen
2011-04-14 20:01 ` [PATCH 3/3] reuse __free_pages_exact() in __alloc_pages_exact() Dave Hansen
2011-04-14 20:01 ` Dave Hansen
2011-04-14 22:00 ` David Rientjes
2011-04-14 22:00 ` David Rientjes
2011-04-14 22:07 ` Dave Hansen
2011-04-14 22:07 ` Dave Hansen
2011-04-14 22:09 ` David Rientjes
2011-04-14 22:09 ` David Rientjes
2011-04-29 14:17 ` [PATCH 1/3] rename alloc_pages_exact() Timur Tabi
2011-04-29 14:17 ` Timur Tabi
-- strict thread matches above, loose matches on Subject: below --
2011-04-11 22:03 Dave Hansen
2011-04-11 22:03 ` [PATCH 2/3] make new alloc_pages_exact() Dave Hansen
2011-04-11 22:03 ` Dave Hansen
2011-04-11 22:22 ` Andrew Morton
2011-04-11 22:22 ` Andrew Morton
2011-04-11 22:36 ` Dave Hansen
2011-04-11 22:36 ` Dave Hansen
2011-04-11 22:42 ` Timur Tabi
2011-04-11 22:42 ` Timur Tabi
2011-04-12 10:28 ` Michal Nazarewicz
2011-04-12 10:28 ` Michal Nazarewicz
2011-04-12 15:04 ` Dave Hansen
2011-04-12 15:04 ` Dave Hansen
2011-04-12 15:58 ` Michal Nazarewicz
2011-04-12 15:58 ` Michal Nazarewicz
2011-04-13 23:23 ` Dave Hansen
2011-04-13 23:23 ` Dave Hansen
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