From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 1 Dec 2008 19:04:55 +0100 From: Nick Piggin Subject: Re: [patch][rfc] fs: shrink struct dentry Message-ID: <20081201180455.GJ10790@wotan.suse.de> References: <20081201083343.GC2529@wotan.suse.de> <20081201175113.GA16828@totally.trollied.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081201175113.GA16828@totally.trollied.org.uk> Sender: owner-linux-mm@kvack.org Return-Path: To: John Levon Cc: linux-fsdevel@vger.kernel.org, Linux Memory Management List , robert.richter@amd.com, oprofile-list@lists.sf.net List-ID: On Mon, Dec 01, 2008 at 05:51:13PM +0000, John Levon wrote: > On Mon, Dec 01, 2008 at 09:33:43AM +0100, Nick Piggin wrote: > > > I then got rid of the d_cookie pointer. This shrinks it to 192 bytes. Rant: > > why was this ever a good idea? The cookie system should increase its hash > > size or use a tree or something if lookups are a problem. > > Are you saying you've made this change without even testing its > performance impact? For oprofile case (maybe if you are profiling hundreds of vmas and overflow the 4096 byte hash table), no. That case is uncommon and must be fixed in the dcookie code (as I said, trivial with changing data structure). I don't want this pointer in struct dentry regardless of a possible tiny benefit for oprofile. -- 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