From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <44C8C80F.8010705@mbligh.org> Date: Thu, 27 Jul 2006 07:05:03 -0700 From: "Martin J. Bligh" MIME-Version: 1.0 Subject: Re: [PATCH] mm: use-once cleanup References: <1153168829.31891.89.camel@lappy> <44C86FB9.6090709@redhat.com> <20060727011204.87033366.akpm@osdl.org> In-Reply-To: <20060727011204.87033366.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Rik van Riel , a.p.zijlstra@chello.nl, linux-mm@kvack.org, torvalds@osdl.org, piggin@cyberone.com.au, linux-kernel@vger.kernel.org, Andy Whitcroft List-ID: >>Peter Zijlstra wrote: >> >> >>>Hi, >>> >>>This is yet another implementation of the PG_useonce cleanup spoken of >>>during the VM summit. >>> >>> >>After getting bitten by rsync yet again, I guess it's time to insist >>that this patch gets merged... >> >>Andrew, could you merge this? Pretty please? ;) >> >> >> > >Guys, this is a performance patch, right? > >One which has no published performance testing results, right? > >It would be somewhat odd to merge it under these circumstances. > >And this applies to all of these >hey-this-is-cool-but-i-didnt-bother-testing-it MM patches which people are >throwing around. This stuff is *hard*. It has a bad tendency to cause >nasty problems which only become known months after the code is merged. > >I shouldn't have to describe all this, but > >- Identify the workloads which it's supposed to improve, set up tests, > run tests, publish results. > >- Identify the workloads which it's expected to damage, set up tests, run > tests, publish results. > >- Identify workloads which aren't expected to be impacted, make a good > effort at demonstrating that they are not impacted. > >- Perform stability/stress testing, publish results. > >Writing the code is about 5% of the effort for this sort of thing. > >Yes, we can toss it in the tree and see what happens. But it tends to be >the case that unless someone does targetted testing such as the above, >regressions simply aren't noticed for long periods of time. schmuck gets to do the legwork when people report problems> > >Just the (unchangelogged) changes to the when-to-call-mark_page_accessed() >logic are a big deal. Probably these should be a separate patch - >separately changelogged, separately tested, separately justified. > >Performance testing is *everything* for this sort of patch and afaict none >has been done, so it's as if it hadn't been written, no? >- > > > Rik / Peter ... I lost the original mail + patch, but if you put it up on a URL somewhere, Andy would probably run it through the test harness for at least some basic perf testing, if you ask him ;-) Probably against mainline, not -mm, as -mm seems to have other problems right now. M. -- 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