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 6EBF6C38145 for ; Wed, 7 Sep 2022 14:29:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230079AbiIGO3T (ORCPT ); Wed, 7 Sep 2022 10:29:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229685AbiIGO3P (ORCPT ); Wed, 7 Sep 2022 10:29:15 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9444A7C509 for ; Wed, 7 Sep 2022 07:29:10 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 320FB617D2 for ; Wed, 7 Sep 2022 14:29:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96623C433D6; Wed, 7 Sep 2022 14:29:08 +0000 (UTC) Date: Wed, 7 Sep 2022 15:29:05 +0100 From: Catalin Marinas To: Liu Song Cc: will@kernel.org, james.morse@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: spectre: increase parameters that can be used to turn off bhb mitigation individually Message-ID: References: <1661514050-22263-1-git-send-email-liusong@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1661514050-22263-1-git-send-email-liusong@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 26, 2022 at 07:40:50PM +0800, Liu Song wrote: > From: Liu Song > > In our environment, it was found that the mitigation BHB has a great > impact on the benchmark performance. For example, in the lmbench test, > the "process fork && exit" test performance drops by 20%. > So it is necessary to have the ability to turn off the mitigation > individually through cmdline, thus avoiding having to compile the > kernel by adjusting the config. > > Signed-off-by: Liu Song If people want to disable this mitigation and know what they are doing, I have no objection: Acked-by: Catalin Marinas (I guess that's more like 6.1 material) -- Catalin