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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 A6DDBC4727C for ; Mon, 21 Sep 2020 23:21:26 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 C37E0239E5 for ; Mon, 21 Sep 2020 23:21:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b="tLvKt6RB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C37E0239E5 Authentication-Results: mail.kernel.org; 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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 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> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Randy Dunlap , Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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.