Zhao Liu <zhao1.liu@xxxxxxxxx> 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 <armbru@xxxxxxxxxx> >> Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache >> object >> >> Zhao Liu <zhao1.liu@xxxxxxxxx> 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 <armbru@xxxxxxxxxx> >> >> Subject: Re: [PATCH 8/8] qemu-options: Add the description of smp-cache >> >> object >> >> >> >> Zhao Liu <zhao1.liu@xxxxxxxxx> writes: >> >> >> >> > Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx> >> >> >> >> 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. [...]