From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1DkVC9-0006mU-8y for user-mode-linux-devel@lists.sourceforge.net; Mon, 20 Jun 2005 15:56:45 -0700 Received: from smtp004.mail.ukl.yahoo.com ([217.12.11.35]) by sc8-sf-mx1.sourceforge.net with smtp (Exim 4.41) id 1DkVC4-0006Ys-IO for user-mode-linux-devel@lists.sourceforge.net; Mon, 20 Jun 2005 15:56:45 -0700 From: Blaisorblade Subject: Re: [uml-devel] [PATCH 6/8] UML - Kill some useless vmalloc tlb flushing References: <200506201851.j5KIpKPr008499@ccure.user-mode-linux.org> In-Reply-To: <200506201851.j5KIpKPr008499@ccure.user-mode-linux.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200506210101.17338.blaisorblade@yahoo.it> Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 21 Jun 2005 01:01:16 +0200 To: user-mode-linux-devel@lists.sourceforge.net Cc: Jeff Dike , akpm@osdl.org, torvalds@osdl.org, linux-kernel@vger.kernel.org On Monday 20 June 2005 20:51, Jeff Dike wrote: > There is absolutely no reason to flush the kernel's VM area during a > tlb_flush_mm. > > This results in a noticable performance increase in the kernel build > benchmark. Andrew: hold off this one, definitely. Jeff: Have you verified this with both modules enabled and iptables (a vmalloc user) compiled modularly? Maybe even non-modular iptables will trigger the bug but let's go for sure. This situation killed a conceptually similar patch in 2.4.24-2um (which did apply until 2.6.11): diff -puN arch/um/kernel/skas/tlb.c~optimization-unstable arch/um/kernel/skas/tlb.c --- UmWorklinux-2.4.24/arch/um/kernel/skas/tlb.c~optimization-unstable 2004-07-02 13:45:07.057643968 +0200 +++ UmWorklinux-2.4.24-paolo/arch/um/kernel/skas/tlb.c 2004-07-02 13:45:14.098573584 +0200 @@ -132,7 +132,9 @@ void flush_tlb_range_skas(struct mm_stru void flush_tlb_mm_skas(struct mm_struct *mm) { +#if 0 flush_tlb_kernel_vm_skas(); +#endif fix_range(mm, 0, host_task_size, 0); } Given that: void flush_tlb_kernel_vm_skas(void) { flush_tlb_kernel_range_skas(start_vm, end_vm); } and flush_tlb_kernel_range_skas was renamed to _common, I argue that this patch is exactly the same one and will have the same bad effect. > Signed-off-by: Jeff Dike > > Index: linux-2.6.12/arch/um/kernel/skas/tlb.c > =================================================================== > --- linux-2.6.12.orig/arch/um/kernel/skas/tlb.c 2005-06-20 > 11:54:56.000000000 -0400 +++ > linux-2.6.12/arch/um/kernel/skas/tlb.c 2005-06-20 12:11:00.000000000 -0400 > @@ -76,7 +76,6 @@ void flush_tlb_mm_skas(struct mm_struct > return; > > fix_range(mm, 0, host_task_size, 0); > - flush_tlb_kernel_range_common(start_vm, end_vm); > } > > void force_flush_all_skas(void) -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel