From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 8 Apr 2008 14:22:32 -0700 From: Andrew Morton Subject: Re: [patch 18/18] dentries: dentry defragmentation Message-Id: <20080408142232.8ac243bc.akpm@linux-foundation.org> In-Reply-To: References: <20080404230158.365359425@sgi.com> <20080404230229.922470579@sgi.com> <20080407231434.88352977.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: linux-mm@kvack.org, Mel Gorman , andi@firstfloor.org, Nick Piggin , Rik van Riel , Pekka Enberg List-ID: On Tue, 8 Apr 2008 14:14:33 -0700 (PDT) Christoph Lameter wrote: > > More importantly - what is the worst success rate, and under which > > circumstances will it occur, and what are the consequences? > > If just dentries remain that are pinned then the function > will not succeed and the slab page will be marked unkickable and no longer > scanned. That doesn't address my overall concern here. We know from hard experience that scanning code tends to have failure scenarios where it expends large amounts of CPU time not achieving much. What workloads are most likely to trigger that sort of behaviour with these changes? How do we establish such failure scenarios and test them? It could be that the non-kickable flag saves us from all such cases, dunno. -- 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