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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 A75AFC433E0 for ; Fri, 3 Jul 2020 09:56:56 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 7F61E20723 for ; Fri, 3 Jul 2020 09:56:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F61E20723 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jrIQv-0001Ol-SW; Fri, 03 Jul 2020 09:56:37 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jrIQv-0001Og-1e for xen-devel@lists.xenproject.org; Fri, 03 Jul 2020 09:56:37 +0000 X-Inumbo-ID: 7b510e18-bd13-11ea-bb8b-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 7b510e18-bd13-11ea-bb8b-bc764e2007e4; Fri, 03 Jul 2020 09:56:36 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9023BB1FA; Fri, 3 Jul 2020 09:56:35 +0000 (UTC) Subject: Re: [PATCH v4 03/10] tools/libxl: add vmtrace_pt_size parameter To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , =?UTF-8?Q?Micha=c5=82_Leszczy=c5=84ski?= References: <5f4f4b1afa432258daff43f2dc8119b6a441fff4.1593519420.git.michal.leszczynski@cert.pl> <20200702090047.GX735@Air-de-Roger> <1505813895.18300396.1593707008144.JavaMail.zimbra@cert.pl> <20200703094438.GY735@Air-de-Roger> From: Jan Beulich Message-ID: Date: Fri, 3 Jul 2020 11:56:38 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200703094438.GY735@Air-de-Roger> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , tamas lengyel , Wei Liu , Andrew Cooper , Ian Jackson , George Dunlap , luwei kang , Anthony PERARD , xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 03.07.2020 11:44, Roger Pau Monné wrote: > On Thu, Jul 02, 2020 at 06:23:28PM +0200, Michał Leszczyński wrote: >> ----- 2 lip 2020 o 11:00, Roger Pau Monné roger.pau@citrix.com napisał(a): >> >>> On Tue, Jun 30, 2020 at 02:33:46PM +0200, Michał Leszczyński wrote: >>>> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h >>>> index 59bdc28c89..7b8289d436 100644 >>>> --- a/xen/include/public/domctl.h >>>> +++ b/xen/include/public/domctl.h >>>> @@ -92,6 +92,7 @@ struct xen_domctl_createdomain { >>>> uint32_t max_evtchn_port; >>>> int32_t max_grant_frames; >>>> int32_t max_maptrack_frames; >>>> + uint8_t vmtrace_pt_order; >>> >>> I've been thinking about this, and even though this is a domctl (so >>> not a stable interface) we might want to consider using a size (or a >>> number of pages) here rather than an order. IPT also supports >>> TOPA mode (kind of a linked list of buffers) that would allow for >>> sizes not rounded to order boundaries to be used, since then only each >>> item in the linked list needs to be rounded to an order boundary, so >>> you could for example use three 4K pages in TOPA mode AFAICT. >>> >>> Roger. >> >> In previous versions it was "size" but it was requested to change it >> to "order" in order to shrink the variable size from uint64_t to >> uint8_t, because there is limited space for xen_domctl_createdomain >> structure. > > It's likely I'm missing something here, but I wasn't aware > xen_domctl_createdomain had any constrains regarding it's size. It's > currently 48bytes which seems fairly small. Additionally I would guess a uint32_t could do here, if the value passed was "number of pages" rather than "number of bytes"? Jan