From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [RFC] Event counters [1/3]: Basic counter functionality From: Nick Piggin In-Reply-To: <20060102214016.GA13905@dmt.cnet> References: <20051220235733.30925.55642.sendpatchset@schroedinger.engr.sgi.com> <20051231064615.GB11069@dmt.cnet> <43B63931.6000307@yahoo.com.au> <20051231202602.GC3903@dmt.cnet> <20060102214016.GA13905@dmt.cnet> Content-Type: text/plain Date: Tue, 03 Jan 2006 16:11:46 +1100 Message-Id: <1136265106.5261.34.camel@npiggin-nld.site> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Marcelo Tosatti Cc: Christoph Lameter , lkml , linux-mm@kvack.org, Andi Kleen List-ID: On Mon, 2006-01-02 at 19:40 -0200, Marcelo Tosatti wrote: > Nick, > > The following patch: > > - Moves the lightweight "inc/dec" versions of mod_page_state variants > to three underscores, making those the default for locations where enough > locks are held. > I guess I was hoping to try to keep it simple, and just have two variants, the __ version would require the caller to do the locking. In cases like eg. allocstall, they should happen infrequently enough that the extra complexity is probably not worth worrying about. I don't think I commented about the preempt race though (and requirement to have preempt off from process context), which obviously can be a problem as you say (though I think things are currently safe?). > - Make the two-underscore version disable and enable preemption, which > is required to avoid preempt-related races which can result in missed > updates. > > - Extends the lightweight version usage in page reclaim, > pte allocation, and a few other codepaths. > I guess nr_dirty looks OK in the places it can be put under tree_lock. nr_page_table_pages is OK because ptl should be held to prevent preempt. pgrotated and pgactivate should be good because of lru_lock. Thanks for going through these! -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- 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