| Message ID | alpine.LFD.2.02.1211161534220.1238@xanadu.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Nov 16, 2012 at 08:42:13PM +0000, Nicolas Pitre wrote: > On Fri, 16 Nov 2012, Nicolas Pitre wrote: > > > On Fri, 16 Nov 2012, Lorenzo Pieralisi wrote: > > > > > Currently, reading /proc/cpuinfo provides userspace with CPU ID of > > > the CPU carrying out the read from the file. This is fine as long as all > > > CPUs in the system are the same. With the advent of big.LITTLE and > > > heterogenous ARM systems this approach provides user space with incorrect > > > bits of information since CPU ids in the system might differ from the one > > > provided by the CPU reading the file. > > > > > > This patch updates the cpuinfo show function so that a read from > > > /proc/cpuinfo prints HW information for all online CPUs at once, mirroring > > > x86 behaviour. > > > > > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > > > > Acked-by: Nicolas Pitre <nico@linaro.org> > > Sorry, let me take this back. There are a few issues with the output. > > First, the "processor" line is doubled for each core. If glibc actually > looks at those lines to determine the number of CPUs like the nearby > comment says then it'll get twice the actual number of processors. > > And then, there is an annoying empty line between the BogoMIPS line and > the rest of the information for each core. > > So, I'd suggest folding this into your patch, with my ACK of course. > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index 53e532704c..bfa673de9e 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -859,18 +859,18 @@ static int c_show(struct seq_file *m, void *v) > u32 cpuid; > > for_each_online_cpu(i) { > - cpuid = is_smp() ? per_cpu(cpu_data, i).cpuid : read_cpuid_id(); > - seq_printf(m, "Processor\t: %s rev %d (%s)\n", > - cpu_name, cpuid & 15, elf_platform); > - > -#if defined(CONFIG_SMP) > /* > * glibc reads /proc/cpuinfo to determine the number of > * online processors, looking for lines beginning with > * "processor". Give glibc what it expects. > */ > seq_printf(m, "processor\t: %d\n", i); > - seq_printf(m, "BogoMIPS\t: %lu.%02lu\n\n", > + cpuid = is_smp() ? per_cpu(cpu_data, i).cpuid : read_cpuid_id(); > + seq_printf(m, "model name\t: %s rev %d (%s)\n", > + cpu_name, cpuid & 15, elf_platform); Ok, but for sake of precision if this is a problem, it is a problem even for the current kernel right ? If we consider the line starting with "Processor", we would end up parsing one CPU more than we should. I will apply your changes. Thanks, Lorenzo
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 53e532704c..bfa673de9e 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -859,18 +859,18 @@ static int c_show(struct seq_file *m, void *v) u32 cpuid; for_each_online_cpu(i) { - cpuid = is_smp() ? per_cpu(cpu_data, i).cpuid : read_cpuid_id(); - seq_printf(m, "Processor\t: %s rev %d (%s)\n", - cpu_name, cpuid & 15, elf_platform); - -#if defined(CONFIG_SMP) /* * glibc reads /proc/cpuinfo to determine the number of * online processors, looking for lines beginning with * "processor". Give glibc what it expects. */ seq_printf(m, "processor\t: %d\n", i); - seq_printf(m, "BogoMIPS\t: %lu.%02lu\n\n", + cpuid = is_smp() ? per_cpu(cpu_data, i).cpuid : read_cpuid_id(); + seq_printf(m, "model name\t: %s rev %d (%s)\n", + cpu_name, cpuid & 15, elf_platform); + +#if defined(CONFIG_SMP) + seq_printf(m, "BogoMIPS\t: %lu.%02lu\n", per_cpu(cpu_data, i).loops_per_jiffy / (500000UL/HZ), (per_cpu(cpu_data, i).loops_per_jiffy / (5000UL/HZ)) % 100); #else