From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 10 Jan 2001 15:57:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Jan 2001 15:57:18 -0500 Received: from 213.237.12.194.adsl.brh.worldonline.dk ([213.237.12.194]:3161 "HELO firewall.jaquet.dk") by vger.kernel.org with SMTP id ; Wed, 10 Jan 2001 15:57:10 -0500 Date: Wed, 10 Jan 2001 21:57:01 +0100 From: Rasmus Andersen To: linux-kernel@vger.kernel.org Subject: [uPATCH] Nulling mmap_cache iff needed (2.4.0) Message-ID: <20010110215701.D971@jaquet.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi. The following (trivial) patch against 2.4.0 (but should apply cleanly against 241p1) makes do_munmap only null our precious cache if the pointer contained therein is invalidated by the unmapping. I doubt it will make any measurable difference but it seems straightforward enough to be done anyway. Running kernel compiles and starting X/gnome with this patch raises my cache hit rate a couple of percentage points, and I have a feeling that there might be work loads out there that hit this kernel path more often that these. Comments? diff -aur linux-2.4.0-clean/mm/mmap.c linux/mm/mmap.c --- linux-2.4.0-clean/mm/mmap.c Sat Dec 30 18:35:19 2000 +++ linux/mm/mmap.c Tue Jan 9 23:30:03 2001 @@ -712,7 +712,10 @@ if (mm->mmap_avl) avl_remove(mpnt, &mm->mmap_avl); } - mm->mmap_cache = NULL; /* Kill the cache. */ + if (mm->mmap_cache && mm->mmap_cache->vm_start < addr+len + && mm->mmap_cache->vm_end > addr) + mm->mmap_cache = NULL; /* Kill the cache. */ + spin_unlock(&mm->page_table_lock); /* Ok - we have the memory areas we should free on the 'free' list, -- Regards, Rasmus(rasmus@jaquet.dk) "It's like an Alcatraz around my neck." -Boston mayor Menino on the shortage of city parking spaces - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/