From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.18.225]) by e23smtp02.au.ibm.com (8.13.1/8.13.1) with ESMTP id l7TMRJ0S001292 for ; Thu, 30 Aug 2007 08:27:19 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.250.244]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id l7TMUpcV203478 for ; Thu, 30 Aug 2007 08:30:51 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l7TMRH2I018657 for ; Thu, 30 Aug 2007 08:27:17 +1000 Message-ID: <46D5F2BB.8010203@linux.vnet.ibm.com> Date: Thu, 30 Aug 2007 03:57:07 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [-mm PATCH] Memory controller improve user interface References: <20070829111030.9987.8104.sendpatchset@balbir-laptop> <1188413148.28903.113.camel@localhost> <46D5ED5C.9030405@linux.vnet.ibm.com> <1188425894.28903.140.camel@localhost> In-Reply-To: <1188425894.28903.140.camel@localhost> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: Andrew Morton , Linux Kernel Mailing List , Linux MM Mailing List , David Rientjes , Linux Containers , Paul Menage List-ID: Dave Hansen wrote: > On Thu, 2007-08-30 at 03:34 +0530, Balbir Singh wrote: >> I've thought about this before. The problem is that a user could >> set his limit to 10000 bytes, but would then see the usage and >> limit round to the closest page boundary. This can be confusing >> to a user. > > True, but we're lying if we allow a user to set their limit there, > because we can't actually enforce a limit at 8,192 bytes vs 10,000. > They're the same limit as far as the kernel is concerned. > > Why not just -EINVAL if the value isn't page-aligned? There are plenty > of interfaces in the kernel that require userspace to know the page > size, so this shouldn't be too difficult. True, mmap() is a good example of such an interface for developers, I am not sure about system admins though. To quote Andrew 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. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org