From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261669AbVFZXui (ORCPT ); Sun, 26 Jun 2005 19:50:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261667AbVFZXuh (ORCPT ); Sun, 26 Jun 2005 19:50:37 -0400 Received: from smtp.osdl.org ([65.172.181.4]:44164 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S261669AbVFZXuN (ORCPT ); Sun, 26 Jun 2005 19:50:13 -0400 Date: Sun, 26 Jun 2005 16:49:39 -0700 From: Andrew Morton To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, bcrl@kvack.org Subject: Re: increased translation cache footprint in v2.6 Message-Id: <20050626164939.2f457bf6.akpm@osdl.org> In-Reply-To: <20050626172334.GA5786@logos.cnet> References: <20050626172334.GA5786@logos.cnet> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Marcelo Tosatti wrote: > > As can be seen the number of entries is more than twice (dominated by kernel addresses). But doesn't this: I-TLB userspace misses: 142369 I-TLB userspace misses: 2179 ITLB u: 139190 I-TLB kernel misses: 118288 I-TLB kernel misses: 1369 ITLB k: 116319 D-TLB userspace misses: 222916 D-TLB userspace misses: 180249 DTLB u: 38667 D-TLB kernel misses: 207773 D-TLB kernel misses: 167236 DTLB k: 38273 mean that we're mainly missing on data accesses? > Sorry, I've got no list of functions for these addresses, but it was pretty obvious at the time > looking at the sys_read() codepath and respective virtual addresses. > > Manual reorganization of the functions sounded too messy, although BenL mentions something about > fget_light() can and should be optimized. The workload you're using also does write(), and the write() paths got significantly deeper. Stack misses, perhaps. But a tlb entry caches the translation for a single page, yes?