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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id E2AC1C3DA7F for ; Wed, 7 Aug 2024 09:45:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sbdEM-00006T-Nd; Wed, 07 Aug 2024 05:45:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sbdEK-0008P5-Ds for qemu-devel@nongnu.org; Wed, 07 Aug 2024 05:45:16 -0400 Received: from mgamail.intel.com ([192.198.163.10]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sbdEG-0002hn-Mi for qemu-devel@nongnu.org; Wed, 07 Aug 2024 05:45:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1723023913; x=1754559913; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=52qBbsPBw1CW9TaWGnYB9fhKWhRZ0gzJVUln8IvbArI=; b=FUdLxClooGU7eIk7tpDNlEnd80euBj1lOKLB9D7H29sFoaQUxV4sGDtf jpftontrr+9dvrHSleorKx00nqGkriQQwTKwQY7p5Vw7zSB4JNV4/FyFM bNKMFC7H+oEASI1BSQvMjfeaHO9o1SFXkqpgh6OlpSNuwym+GyDbe2Ryv UTkV9SFSjdK2JjTpEcwILDoBYpVI4sQ67VGfY1yUVxY8DpeXqoHdfF6k3 SLN0LlGrj96DGUGHFzj6m+mJrWcGqygVn9IedNROMaNMXBb4tq5NBteWn q7q4hUsYfaxLIFGUXxjekKu7mjNgkrtVpwzVY0pbwZ3PgKtfSzl+WEUc0 A==; X-CSE-ConnectionGUID: 25e/JwK2TjOMkHF6rwfEzA== X-CSE-MsgGUID: 0ic44X0NR9KU3ylfTLsY6w== X-IronPort-AV: E=McAfee;i="6700,10204,11156"; a="32486475" X-IronPort-AV: E=Sophos;i="6.09,269,1716274800"; d="scan'208";a="32486475" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Aug 2024 02:45:09 -0700 X-CSE-ConnectionGUID: JNzXxyT0QwWPJHLXE0WANw== X-CSE-MsgGUID: YjK0r+O/TcaC1t4EM2x6kg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,269,1716274800"; d="scan'208";a="56482022" Received: from liuzhao-optiplex-7080.sh.intel.com (HELO localhost) ([10.239.160.36]) by fmviesa007.fm.intel.com with ESMTP; 07 Aug 2024 02:45:07 -0700 Date: Wed, 7 Aug 2024 18:00:57 +0800 From: Zhao Liu To: Markus Armbruster Cc: qemu-devel@nongnu.org Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache object Message-ID: References: <20240704031603.1744546-1-zhao1.liu@intel.com> <20240704031603.1744546-9-zhao1.liu@intel.com> <87r0bl35ug.fsf@pond.sub.org> <87bk2nnev2.fsf@pond.sub.org> <87le1psuv3.fsf@pond.sub.org> <87mslweb38.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=192.198.163.10; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.144, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Markus, Just a kindly ping. Hopefully we can continue this discussion when you're free. Regards, Zhao On Fri, Aug 02, 2024 at 03:58:02PM +0800, Zhao Liu wrote: > Date: Fri, 2 Aug 2024 15:58:02 +0800 > From: Zhao Liu > Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache > object > > On Thu, Aug 01, 2024 at 01:28:27PM +0200, Markus Armbruster wrote: > > Date: Thu, 01 Aug 2024 13:28:27 +0200 > > From: Markus Armbruster > > Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache > > object > > > > Zhao Liu writes: > > > > > On Thu, Jul 25, 2024 at 11:07:12AM +0200, Markus Armbruster wrote: > > >> Date: Thu, 25 Jul 2024 11:07:12 +0200 > > >> From: Markus Armbruster > > >> Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache > > >> object > > >> > > >> Zhao Liu writes: > > >> > > >> > Hi Markus and Daniel, > > >> > > > >> > I have the questions about the -object per cache implementation: > > >> > > > >> > On Wed, Jul 24, 2024 at 02:39:29PM +0200, Markus Armbruster wrote: > > >> >> Date: Wed, 24 Jul 2024 14:39:29 +0200 > > >> >> From: Markus Armbruster > > >> >> Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache > > >> >> object > > >> >> > > >> >> Zhao Liu writes: > > >> >> > > >> >> > Hi Markus, > > >> >> > > > >> >> > On Mon, Jul 22, 2024 at 03:37:43PM +0200, Markus Armbruster wrote: > > >> >> >> Date: Mon, 22 Jul 2024 15:37:43 +0200 > > >> >> >> From: Markus Armbruster > > >> >> >> Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache > > >> >> >> object > > >> >> >> > > >> >> >> Zhao Liu writes: > > >> >> >> > > >> >> >> > Signed-off-by: Zhao Liu > > >> >> >> > > >> >> >> This patch is just documentation. The code got added in some previous > > >> >> >> patch. Would it make sense to squash this patch into that previous > > >> >> >> patch? > > >> >> > > > >> >> > OK, I'll merge them. > > >> >> > > > >> >> >> > --- > > >> >> >> > Changes since RFC v2: > > >> >> >> > * Rewrote the document of smp-cache object. > > >> >> >> > > > >> >> >> > Changes since RFC v1: > > >> >> >> > * Use "*_cache=topo_level" as -smp example as the original "level" > > >> >> >> > term for a cache has a totally different meaning. (Jonathan) > > >> >> >> > --- > > >> >> >> > qemu-options.hx | 58 +++++++++++++++++++++++++++++++++++++++++++++++++ > > >> >> >> > 1 file changed, 58 insertions(+) > > >> >> >> > > > >> >> >> > diff --git a/qemu-options.hx b/qemu-options.hx > > >> >> >> > index 8ca7f34ef0c8..4b84f4508a6e 100644 > > >> >> >> > --- a/qemu-options.hx > > >> >> >> > +++ b/qemu-options.hx > > >> >> >> > @@ -159,6 +159,15 @@ SRST > > >> >> >> > :: > > >> >> >> > > > >> >> >> > -machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512 > > >> >> >> > + > > >> >> >> > + ``smp-cache='id'`` > > >> >> >> > + Allows to configure cache property (now only the cache topology level). > > >> >> >> > + > > >> >> >> > + For example: > > >> >> >> > + :: > > >> >> >> > + > > >> >> >> > + -object '{"qom-type":"smp-cache","id":"cache","caches":[{"name":"l1d","topo":"core"},{"name":"l1i","topo":"core"},{"name":"l2","topo":"module"},{"name":"l3","topo":"die"}]}' > > >> >> >> > + -machine smp-cache=cache > > >> >> >> > ERST > > >> >> >> > > > >> >> >> > DEF("M", HAS_ARG, QEMU_OPTION_M, > > >> >> >> > @@ -5871,6 +5880,55 @@ SRST > > >> >> >> > :: > > >> >> >> > > > >> >> >> > (qemu) qom-set /objects/iothread1 poll-max-ns 100000 > > >> >> >> > + > > >> >> >> > + ``-object '{"qom-type":"smp-cache","id":id,"caches":[{"name":cache_name,"topo":cache_topo}]}'`` > > >> >> >> > + Create an smp-cache object that configures machine's cache > > >> >> >> > + property. Currently, cache property only include cache topology > > >> >> >> > + level. > > >> >> >> > + > > >> >> >> > + This option must be written in JSON format to support JSON list. > > >> >> >> > > >> >> >> Why? > > >> >> > > > >> >> > I'm not familiar with this, so I hope you could educate me if I'm wrong. > > >> >> > > > >> >> > All I know so far is for -object that defining a list can only be done in > > >> >> > JSON format and not with a numeric index like a keyval based option, like: > > >> >> > > > >> >> > -object smp-cache,id=cache0,caches.0.name=l1i,caches.0.topo=core: Parameter 'caches' is missing > > >> >> > > > >> >> > the above doesn't work. > > >> >> > > > >> >> > Is there any other way to specify a list in command line? > > >> >> > > >> >> The command line is a big, sprawling mess :) > > >> >> > > >> >> -object supports either a JSON or a QemuOpts argument. *Not* keyval! > > >> >> > > >> >> Both QemuOpts and keyval parse something like KEY=VALUE,... Keyval > > >> >> supports arrays and objects via dotted keys. QemuOpts doesn't natively > > >> >> support arrays and objects, but its users can hack around that > > >> >> limitation in various ways. -object doesn't. So you're right, it's > > >> >> JSON or bust here. > > >> >> > > >> >> However, if we used one object per cache instead, we could get something > > >> >> like > > >> >> > > >> >> -object smp-cache,name=l1d,... > > >> >> -object smp-cache,name=l1u,... > > >> >> -object smp-cache,name=l2,... > > >> >> ... > > >> > > > >> > Current, I use -object to create a smp_cache object, and link it to > > >> > MachineState by -machine,smp-cache=obj_id. > > >> > > > >> > Then for the objects per cache, how could I link them to machine? > > >> > > > >> > Is it possible that I create something static in smp_cache.c and expose > > >> > all the cache information to machine through some interface? > > >> > > >> Good questions. However, before we head deeper into the weeds here, I > > >> feel we should discuss the things below. And before we do that, I need > > >> a clear understanding of the use case. Elsewhere in this thread, I just > > >> described the use case as I understand it. Please reply there. I'll > > >> then come back to this message. > > >> > > >> [...] > > > > > > Jonathan and I provided different use cases for x86 and Arm. Could we > > > come back here to continue the discussion? :) > > > > Can you provide a brief summary of the design alternatives that have > > been proposed so far? Because I've lost track. > > No problem! > > Currently, we have the following options: > > * 1st: The first one is just to configure cache topology with several > options in -smp: > > -smp l1i-cache-topo=core,l1d-cache-topo-core > > This one lacks scalability to support the cache size that ARM will > need in the future. > > > * 2nd: The cache list object in -smp. > > The idea was to use JSON to configure the cache list. However, the > underlying implementation of -smp at the moment is keyval parsing, > which is not compatible with JSON. > > If we can not insist on JSON format, then cache lists can also be > implemented in the following way: > > -smp caches.0.name=l1i,caches.0.topo=core,\ > caches.1.name=l1d,caches.1.topo=core > > > * 3rd: The cache list object linked in -machine. > > Considering that -object is JSON-compatible so that defining lists via > JSON is more friendly, I implemented the caches list via -object and > linked it to MachineState: > > -object '{"qom-type":"smp-cache","id":"obj","caches":[{"name":"l1d","topo":"core"},{"name":"l1i","topo":"core"}]}' > -machine smp-caches=obj > > > * 4th: The per cache object without any list: > > -object smp-cache,id=cache0,name=l1i,topo=core \ > -object smp-cache,id=cache1,name=l1d,topo=core > > This proposal is clearer, but there are a few opens: > - I plan to push qom-topo forward, which would abstract CPU related > topology levels and cache to "device" instead of object. Is there a > conflict here? > > - Multiple cache objects can't be linked to the machine on the command > line, so I maintain a static cache list in smp_cache.c and expose > the cache information to the machine through some interface. is this > way acceptable? > > > In summary, the 4th proposal was the most up in the air, as it looked to > be conflict with the hybrid topology I wanted to do (and while hybrid > topology may not be accepted by the community either, I thought it would > be best for the two work to be in the same direction). > > The difference between 2nd and 3rd is about the JSON requirement, if JSON > is mandatory for now then it's 3rd, if it's not mandatory (or accept to > make -machine/-smp support JSON in the future), 2nd looks cleaner, which > puts the caches list in -smp. > > Regards, > Zhao > > >