From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3B55C5AD4C for ; Thu, 16 Nov 2023 10:14:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345016AbjKPKOY (ORCPT ); Thu, 16 Nov 2023 05:14:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235675AbjKPKOV (ORCPT ); Thu, 16 Nov 2023 05:14:21 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B046D5C for ; Thu, 16 Nov 2023 02:14:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700129655; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/qSf17nLKwBzvhXGOsVf7cFolqlSlgq1S8Xm68Mw6Xg=; b=Wy1BUoBCI/lLr0wG67a9lJBUt0VbZxlzH5ums4U8JErYzGFaQAuZVl5Cr1OeB0uWV6tbiJ jmhgfYaxEEP/cPjXHPQe6necmycLOGQQtFlbfPcfc04fuE8/tU1TUc7BccHAv/eApz05cu I64LtjljL1vl5DoL5QjW8kjKldEzc2Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-403-dMjoYVQONpiGjZaMrqRBHA-1; Thu, 16 Nov 2023 05:14:08 -0500 X-MC-Unique: dMjoYVQONpiGjZaMrqRBHA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 07D0C101A529; Thu, 16 Nov 2023 10:14:08 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 99618492BFD; Thu, 16 Nov 2023 10:14:04 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <4c0c3ee6cfa84d21a807055bc1aa27b8@AcuMS.aculab.com> References: <4c0c3ee6cfa84d21a807055bc1aa27b8@AcuMS.aculab.com> <202311061616.cd495695-oliver.sang@intel.com> <3865842.1700061614@warthog.procyon.org.uk> <20231115190938.GGZVUXcuUjI3i1JRAB@fat_crate.local> To: David Laight Cc: dhowells@redhat.com, 'Linus Torvalds' , Borislav Petkov , kernel test robot , "oe-lkp@lists.linux.dev" , "lkp@intel.com" , "linux-kernel@vger.kernel.org" , Christian Brauner , Alexander Viro , Jens Axboe , Christoph Hellwig , Christian Brauner , Matthew Wilcox , "ying.huang@intel.com" , "feng.tang@intel.com" , "fengwei.yin@intel.com" Subject: Re: [linus:master] [iov_iter] c9eec08bac: vm-scalability.throughput -16.9% regression MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <97467.1700129643.1@warthog.procyon.org.uk> Date: Thu, 16 Nov 2023 10:14:03 +0000 Message-ID: <97468.1700129643@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Laight wrote: > On haswell (which is now quite old) both 'rep movsb' and > 'rep movsq' copy 16 bytes/clock unless the destination > is 32 byte aligned when they copy 32 bytes/clock. > Source alignment make no different, neither does byte > alignment. I think the i3-4170 cpu I'm using is Haswell. Does that mean for my particular cpu, just using inline "rep movsb" is the best choice? David