From: Dave Hansen <haveblue@us.ibm.com>
To: balbir@linux.vnet.ibm.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM Mailing List <linux-mm@kvack.org>,
David Rientjes <rientjes@google.com>,
Linux Containers <containers@lists.osdl.org>,
Paul Menage <menage@google.com>
Subject: Re: [-mm PATCH] Memory controller improve user interface
Date: Wed, 29 Aug 2007 15:36:40 -0700 [thread overview]
Message-ID: <1188427000.28903.148.camel@localhost> (raw)
In-Reply-To: <46D5F2BB.8010203@linux.vnet.ibm.com>
On Thu, 2007-08-30 at 03:57 +0530, Balbir Singh wrote:
> True, mmap() is a good example of such an interface for developers, I
> am not sure about system admins though.
>
> To quote Andrew
> <quote>
> Reporting tools could run getpagesize() and do the arithmetic, but we
> generally try to avoid exposing PAGE_SIZE, HZ, etc to userspace in this
> manner.
> </quote>
Well, rounding to PAGE_SIZE exposes PAGE_SIZE as well, just in a
non-intuitive fashion. :)
If we're going to modify what the user specifies, we should probably at
least mandate that writes are only a "suggestion" and users must read
back the value to ensure what actually got committed.
If we're going to round in any direction, shouldn't we round up? If a
user specifies 4097 bytes and uses two pages, we don't want to complain
when they hit that second page.
-- Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <haveblue@us.ibm.com>
To: balbir@linux.vnet.ibm.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM Mailing List <linux-mm@kvack.org>,
David Rientjes <rientjes@google.com>,
Linux Containers <containers@lists.osdl.org>,
Paul Menage <menage@google.com>
Subject: Re: [-mm PATCH] Memory controller improve user interface
Date: Wed, 29 Aug 2007 15:36:40 -0700 [thread overview]
Message-ID: <1188427000.28903.148.camel@localhost> (raw)
In-Reply-To: <46D5F2BB.8010203@linux.vnet.ibm.com>
On Thu, 2007-08-30 at 03:57 +0530, Balbir Singh wrote:
> True, mmap() is a good example of such an interface for developers, I
> am not sure about system admins though.
>
> To quote Andrew
> <quote>
> Reporting tools could run getpagesize() and do the arithmetic, but we
> generally try to avoid exposing PAGE_SIZE, HZ, etc to userspace in this
> manner.
> </quote>
Well, rounding to PAGE_SIZE exposes PAGE_SIZE as well, just in a
non-intuitive fashion. :)
If we're going to modify what the user specifies, we should probably at
least mandate that writes are only a "suggestion" and users must read
back the value to ensure what actually got committed.
If we're going to round in any direction, shouldn't we round up? If a
user specifies 4097 bytes and uses two pages, we don't want to complain
when they hit that second page.
-- Dave
--
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next prev parent reply other threads:[~2007-08-29 22:36 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-29 11:10 [-mm PATCH] Memory controller improve user interface Balbir Singh
2007-08-29 11:10 ` Balbir Singh
2007-08-29 15:28 ` Paul Menage
2007-08-29 15:28 ` Paul Menage
2007-08-29 16:07 ` Balbir Singh
2007-08-29 16:07 ` Balbir Singh
2007-08-29 16:17 ` Paul Menage
2007-08-29 16:17 ` Paul Menage
2007-08-29 18:45 ` Dave Hansen
2007-08-29 18:45 ` Dave Hansen
2007-08-29 22:04 ` Balbir Singh
2007-08-29 22:04 ` Balbir Singh
2007-08-29 22:04 ` Balbir Singh
2007-08-29 22:18 ` Dave Hansen
2007-08-29 22:18 ` Dave Hansen
2007-08-29 22:20 ` Paul Menage
2007-08-29 22:20 ` Paul Menage
2007-08-29 22:25 ` Dave Hansen
2007-08-29 22:25 ` Dave Hansen
2007-08-29 22:37 ` Balbir Singh
2007-08-29 22:37 ` Balbir Singh
2007-08-29 22:37 ` Balbir Singh
2007-08-30 5:38 ` KAMEZAWA Hiroyuki
2007-08-30 5:38 ` KAMEZAWA Hiroyuki
[not found] ` <20070830143859.e9d3511a.kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
2007-08-30 9:13 ` Balbir Singh
2007-08-30 9:13 ` Balbir Singh
2007-08-30 9:13 ` Balbir Singh
2007-08-29 22:27 ` Balbir Singh
2007-08-29 22:27 ` Balbir Singh
2007-08-29 22:36 ` Dave Hansen [this message]
2007-08-29 22:36 ` Dave Hansen
2007-08-29 22:44 ` Balbir Singh
2007-08-29 22:44 ` Balbir Singh
2007-08-29 22:44 ` Balbir Singh
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