[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v9 1/6] x86: detect and initialize Cache QoS Monitoring feature
>>> On 18.03.14 at 03:02, "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx> wrote: >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] >> >>> On 03.03.14 at 14:21, "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx> wrote: >> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] >> >> >>> On 19.02.14 at 07:32, Dongxiao Xu <dongxiao.xu@xxxxxxxxx> wrote: >> >> > + /* Allocate CQM buffer size in initialization stage */ >> >> > + cqm_pages = ((cqm->max_rmid + 1) * sizeof(domid_t) + >> >> > + (cqm->max_rmid + 1) * sizeof(uint64_t) * NR_CPUS)/ >> >> >> >> Does this really need to be NR_CPUS (rather than nr_cpu_ids)? >> > >> > Okay. >> > As you mentioned in later comment, the CQM data is indexed per-socket. >> > Here we use NR_CPUS or nr_cpu_ids because it is big enough to cover the >> > possible socket number in the system (even consider hotplug case). >> > Is there a better way that we can get the system socket number (including >> > the case even there is no CPU in that socket)? >> >> I think we should at least get the estimation as close as possible: >> Count the sockets that we know of (i.e. that have at least one >> core/thread) and add the number of "disabled" (hot-pluggable) >> CPUs if ACPI doesn't surface enough information to associate >> them with a socket (but I think MADT provides all the needed data). > > It seems that MADT table doesn't contain the socket number information... > > Considering that it is difficult to get the accurate socket number at system > initialization time, what about we allocate/free the CQM related memory at > runtime when user admin really issues the QoS query command? > With this approach, the data sharing between Xen and Dom0 tools should be > much less since we know: > - How many processor sockets are active in the system. > - How many active RMIDs are in use in the system. > > With above, we didn't need to always using the max_rmid * max_socket memory > to share a lot of unnecessary "zero" data, and the new sharing data should be > less than one page. > What's your opinion about that? If you can get this to work, that would seem like a pretty optimal solution. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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