From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [-mm PATCH] Memory controller improve user interface Date: Thu, 30 Aug 2007 04:14:15 +0530 Message-ID: <46D5F6BF.2080607@linux.vnet.ibm.com> References: <20070829111030.9987.8104.sendpatchset@balbir-laptop> <1188413148.28903.113.camel@localhost> <46D5ED5C.9030405@linux.vnet.ibm.com> <1188425894.28903.140.camel@localhost> <46D5F2BB.8010203@linux.vnet.ibm.com> <1188427000.28903.148.camel@localhost> Reply-To: balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1188427000.28903.148.camel@localhost> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Dave Hansen Cc: Linux Kernel Mailing List , Linux MM Mailing List , David Rientjes , Linux Containers , Andrew Morton , Paul Menage List-Id: containers.vger.kernel.org Dave Hansen wrote: > 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 >> >> 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. >> > > Well, rounding to PAGE_SIZE exposes PAGE_SIZE as well, just in a > non-intuitive fashion. :) > Agreed, but the user might choose to ignore it altogether. > 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. > Agreed, excellent suggestion! > 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. > Absolutely, I used rounding to mean round up, truncation for rounding down. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL