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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 BC853C4727F for ; Mon, 21 Sep 2020 23:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 378422388B for ; Mon, 21 Sep 2020 23:19:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b="tLvKt6RB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728822AbgIUXTd (ORCPT ); Mon, 21 Sep 2020 19:19:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728704AbgIUXTc (ORCPT ); Mon, 21 Sep 2020 19:19:32 -0400 Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99532C061755; Mon, 21 Sep 2020 16:19:32 -0700 (PDT) Received: by ozlabs.org (Postfix, from userid 1003) id 4BwL4K2tFPz9sSt; Tue, 22 Sep 2020 09:19:29 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ozlabs.org; s=201707; t=1600730369; bh=Gh/jGMCMQmrrfp+HhoHjE8q2QWpEvx5rxPTcdpfPEt4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tLvKt6RBA7E4vUVZYVD3O0hQckC/kqu0Y6WFB8O4lOYXfgvdTXK9gsmS2BD7ls6Xr A1w4ELvBsIAhbgPaFFbignPhVBc1+vqX+JLVk+i4hT/EJmapByfasDbtvk9ZdIRSiY VVBZFvHlCGQiUgyF/mZ9yP+i3k8ThJdX+sjKTRfWPcM8mzSoNZ9quQ9ynaUbGeGfwD zHkAT3JewA/O4SLmM/ZXDet68DJvmz2PUC/X2oxcj8Ee8mh4Y6Ut6o1RPksx6psUXi nbGOfz1G8iQA3tLtlpbbVNHjCbXyoRskt/SrPz3ILNA3SiwzpqzpxiLangK6IevOV/ epbK+jzQSZ3hw== Date: Tue, 22 Sep 2020 09:19:25 +1000 From: Paul Mackerras To: sathnaga@linux.vnet.ibm.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Michael Ellerman , Jonathan Corbet , Randy Dunlap Subject: Re: [PATCH V2] Doc: admin-guide: Add entry for kvm_cma_resv_ratio kernel param Message-ID: <20200921231925.GA348814@thinks.paulus.ozlabs.org> References: <20200921090220.14981-1-sathnaga@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921090220.14981-1-sathnaga@linux.vnet.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2020 at 02:32:20PM +0530, sathnaga@linux.vnet.ibm.com wrote: > From: Satheesh Rajendran > > Add document entry for kvm_cma_resv_ratio kernel param which > is used to alter the KVM contiguous memory allocation percentage > for hash pagetable allocation used by hash mode PowerPC KVM guests. > > Cc: linux-kernel@vger.kernel.org > Cc: kvm-ppc@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: Paul Mackerras > Cc: Michael Ellerman > Cc: Jonathan Corbet > Reviewed-by: Randy Dunlap > Signed-off-by: Satheesh Rajendran > --- > > V2: > Addressed review comments from Randy. > > V1: https://lkml.org/lkml/2020/9/16/72 > --- > Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index a1068742a6df..932ed45740c9 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2258,6 +2258,14 @@ > [KVM,ARM] Allow use of GICv4 for direct injection of > LPIs. > > + kvm_cma_resv_ratio=n [PPC] > + Reserves given percentage from system memory area for > + contiguous memory allocation for KVM hash pagetable > + allocation. > + By default it reserves 5% of total system memory. I am concerned that using the term "reserve" here could give the impression that this memory is then not available for any other use. It is in fact available for other uses as long as they are movable allocations. So this memory is available for uses such as process anonymous memory and page cache, just not for things like kmalloc. I'm not sure what would be a better term than "reserve", though. Perhaps we need to add a sentence something like "The reserved memory is available for use as process memory and page cache when it is not being used by KVM." Paul.