From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3B42D689.97809E5@earthlink.net> Date: Wed, 04 Jul 2001 02:40:41 -0600 From: "Joseph A. Knapka" MIME-Version: 1.0 Subject: Re: [PATCH] initial detailed VM statistics code References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Marcelo Tosatti Cc: linux-mm@kvack.org List-ID: Marcelo Tosatti wrote: > > On Wed, 4 Jul 2001, Joseph A. Knapka wrote: > > > Marcelo Tosatti wrote: > > > > > > Hi, > > > > > > Well, I've started working on VM stats code for 2.4. > > > > > > > Thanks. > > > > It might be useful to have a count of the number of PTEs scanned > > by swap_out(), and the number of those that were unmapped. (I'm > > interested in the scan rate of swap_out() vs refill_inactive_scan()). > > Hum, > > The number of pages with age 0 which have mapped PTEs (thus cannot be > freed) is what you're looking for ? Well, I'm just not sure :-) I'm looking for anything practical that would give insight into the VM system. Maybe if I looked at PTE scan rates and page frame scan rates for a while I'd conclude that in fact, age-zero-but-unfreeable-page-count is a critical number (it seems like it would be). But maybe I'd conclude something else. I guess from a purely pedagogical standpoint, I'm interested in knowing the general shape of the mapping from VM onto physical memory at a given time - how much total virtual space is being mapped into RAM, and how it's shared, and whether VM is scanned at approximately the same relative rate as physical RAM. That information may be utterly useless from a VM tuning standpoint, I don't know. It would, IMO, be nice to have as much VM state as possible exported for use by modules (if requested by the user at configuration time), so that we can gather whatever statistics we want without patching the kernel a lot. Thanks, -- Joe Knapka "You know how many remote castles there are along the gorges? You can't MOVE for remote castles!" -- Lu Tze re. Uberwald // Linux MM Documentation in progress: // http://home.earthlink.net/~jknapka/linux-mm/vmoutline.html * Evolution is an "unproven theory" in the same sense that gravity is. * -- 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/