From mboxrd@z Thu Jan 1 00:00:00 1970 From: kanoj@google.engr.sgi.com (Kanoj Sarcar) Message-Id: <200003290159.RAA95992@google.engr.sgi.com> Subject: Re: how text page of executable are shared ? Date: Tue, 28 Mar 2000 17:59:45 -0800 (PST) In-Reply-To: <20000329020103.I17288@redhat.com> from "Stephen C. Tweedie" at Mar 29, 2000 02:01:03 AM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: "Stephen C. Tweedie" Cc: Mark Hahn , linux-mm@kvack.org List-ID: > > Hi, > > On Tue, Mar 28, 2000 at 10:58:00AM -0500, Mark Hahn wrote: > > > > could you comment on a problem I'm seeing in the current (pre3) VM? > > the situation is a 256M machine, otherwise idle (random daemons, no X, > > couple ssh's) and a process that sequentially traverses 12 40M files > > by mmaping them (and munmapping them, in order, one at a time.) > > > > the observation is that all goes well until the ~6th file, when we > > run out of unused ram. then we start _swapping_! the point is that > > shrink_mmap should really be scavenging those now unmapped files, > > shouldn't it? > > Well, you've filled the whole of memory with recently referenced page > cache pages. The page cache scanner can now scan the whole of physical > memory without finding anything which is "old" enough to be evicted. > It is only natural that it will start swapping at that point! > > The swapping should be brief if all is working properly, though, as the > shrink_mmap() will rapidly find itself on the second pass over memory > and will start finding things which have been aged on the first pass > and not used since. > > --Stephen > -- > 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.eu.org/Linux-MM/ > As I mentioned to Mark in private mail, it might be worthwhile looking into the possiblity of using MADV_DONTNEED to discard file pages from the cache. In some os'es, I think msync(MS_INVALIDATE) actually takes the page out from the cache. Kanoj -- 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.eu.org/Linux-MM/