From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43479) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZYASU-0006k9-Dq for qemu-devel@nongnu.org; Sat, 05 Sep 2015 06:12:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZYASQ-00039q-D3 for qemu-devel@nongnu.org; Sat, 05 Sep 2015 06:12:30 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:35207) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZYASQ-00039T-7P for qemu-devel@nongnu.org; Sat, 05 Sep 2015 06:12:26 -0400 Received: by pacfv12 with SMTP id fv12so48754725pac.2 for ; Sat, 05 Sep 2015 03:12:24 -0700 (PDT) References: <1441342300-28318-1-git-send-email-david@gibson.dropbear.id.au> <1441342300-28318-2-git-send-email-david@gibson.dropbear.id.au> <20150904045641.GS6537@voom.redhat.com> From: Alexey Kardashevskiy Message-ID: <55EAC003.7020703@ozlabs.ru> Date: Sat, 5 Sep 2015 20:12:19 +1000 MIME-Version: 1.0 In-Reply-To: <20150904045641.GS6537@voom.redhat.com> Content-Type: text/plain; charset=koi8-r; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFCv2 1/2] pseries: Fix incorrect calculation of threads per socket for chip-id List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson , mdroth@linux.vnet.ibm.com Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, agraf@suse.de On 09/04/2015 02:56 PM, David Gibson wrote: > On Fri, Sep 04, 2015 at 02:51:39PM +1000, David Gibson wrote: >> The device tree presented to pseries machine type guests includes an >> ibm,chip-id property which gives essentially the socket number of each >> vcpu core (individual vcpu threads don't get a node in the device >> tree). >> >> To calculate this, it uses a vcpus_per_socket variable computed as >> (smp_cpus / #sockets). This is correct for the usual case where >> smp_cpus == smp_threads * smp_cores * #sockets. >> >> However, you can start QEMU with the number of cores and threads >> mismatching the total number of vcpus (whether that _should_ be >> permitted is a topic for another day). It's a bit hard to say what >> the "real" number of vcpus per socket here is, but for most purposes >> (smp_threads * smp_cores) will more meaningfully match how QEMU >> behaves with respect to socket boundaries. >> >> Signed-off-by: David Gibson > > Gah, sorry, there's a compile error in this. I got sidetracked > between writing and posting and forgot I hadn't fixed it yet. The error, I believe, is "opts" not being used anymore? If so, Reviewed-by: Alexey Kardashevskiy > >> --- >> hw/ppc/spapr.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >> index 783763f..dbc295b 100644 >> --- a/hw/ppc/spapr.c >> +++ b/hw/ppc/spapr.c >> @@ -595,8 +595,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset, >> uint32_t page_sizes_prop[64]; >> size_t page_sizes_prop_size; >> QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL); >> - unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0; >> - uint32_t cpus_per_socket = sockets ? (smp_cpus / sockets) : 1; >> + uint32_t vcpus_per_socket = smp_threads * smp_cores; >> uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)}; >> >> _FDT((fdt_setprop_cell(fdt, offset, "reg", index))); >> @@ -665,7 +664,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset, >> } >> >> _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id", >> - cs->cpu_index / cpus_per_socket))); >> + cs->cpu_index / vcpus_per_socket))); >> >> _FDT((fdt_setprop(fdt, offset, "ibm,pft-size", >> pft_size_prop, sizeof(pft_size_prop)))); > -- Alexey