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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38EB5C433DF for ; Fri, 26 Jun 2020 13:59:14 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 04A76207E8 for ; Fri, 26 Jun 2020 13:59:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HDvJgppX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 04A76207E8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45700 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1joosr-0000SH-AK for qemu-devel@archiver.kernel.org; Fri, 26 Jun 2020 09:59:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41390) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1joos4-0007nt-D8 for qemu-devel@nongnu.org; Fri, 26 Jun 2020 09:58:24 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:57476 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1joos2-0001LQ-Gs for qemu-devel@nongnu.org; Fri, 26 Jun 2020 09:58:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593179901; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IjJiU0asDsiS4+YeM32QII+MWPGHCHjVHIn0rqv5pgI=; b=HDvJgppXH0nQ1jS/iPL/KAs+M9jZDmtOBQ+zuc/LJNZP/RIb+vV7A7dOyqbw8AGrXdpZkP A5QmSpJVdhIkSyklO4jyR181DsyBWbrUx49Yj/EeGO5SKWJUvTn6xG7/eQjHktjV0IuO4B TTn9IcI5qkS+mtFhcEXWIh1milCLcxg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-451--cpZ1g-uP8e-1vqU-4A8ig-1; Fri, 26 Jun 2020 09:58:16 -0400 X-MC-Unique: -cpZ1g-uP8e-1vqU-4A8ig-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 188FE800D5C; Fri, 26 Jun 2020 13:58:14 +0000 (UTC) Received: from [10.36.114.197] (ovpn-114-197.ams2.redhat.com [10.36.114.197]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 01BF360BF4; Fri, 26 Jun 2020 13:58:02 +0000 (UTC) Subject: Re: [PATCH RESEND 5/9] hw/arm/smmuv3: Store the starting level in SMMUTransTableInfo To: Peter Maydell References: <20200611161500.23580-1-eric.auger@redhat.com> <20200611161500.23580-6-eric.auger@redhat.com> From: Auger Eric Message-ID: <0ff6e8e6-0213-13ac-9541-f7353dd1178f@redhat.com> Date: Fri, 26 Jun 2020 15:58:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=eric.auger@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/26 01:49:42 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker , "Michael S. Tsirkin" , Robin Murphy , zhangfei.gao@foxmail.com, QEMU Developers , Peter Xu , qemu-arm , Shameerali Kolothum Thodi , Will Deacon , Rob Herring , Eric Auger Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Peter, On 6/25/20 5:15 PM, Peter Maydell wrote: > On Thu, 11 Jun 2020 at 17:15, Eric Auger wrote: >> >> Compute the starting level on CD decoding and store it >> into SMMUTransTableInfo. We will need this information >> on IOTLB lookup so let's avoid to recompute it each time. >> >> Signed-off-by: Eric Auger > >> --- a/hw/arm/smmu-common.c >> +++ b/hw/arm/smmu-common.c >> @@ -224,7 +224,7 @@ static int smmu_ptw_64(SMMUTransCfg *cfg, >> granule_sz = tt->granule_sz; >> stride = granule_sz - 3; >> inputsize = 64 - tt->tsz; >> - level = 4 - (inputsize - 4) / stride; >> + level = tt->starting_level; > > "4 - (x - 4) / y" doesn't really seem like it's complicated > enough to be worth caching given everything else we do on > a page table walk. Do you have perf figures to indicate that > this change is worthwhile? no I don't have any figure or any setup at the moment to perform that bench. I thought it could only help, was not complicated to store and was of the same kind as the granule size, the input range, ... already stored in SMMUTransTableInfo. Thanks Eric > > thanks > -- PMM >