On 09/01/14 19:31, Greg Kroah-Hartman wrote: > On Thu, Jan 09, 2014 at 07:19:00PM +0000, Sudeep Holla wrote: >> On 08/01/14 20:27, Greg Kroah-Hartman wrote: >>> On Wed, Jan 08, 2014 at 07:26:06PM +0000, Sudeep Holla wrote: >>>> From: Sudeep Holla <sudeep.holla@xxxxxxx> >>>> >>>> This patch adds initial support for providing processor cache information >>>> to userspace through sysfs interface. This is based on x86 implementation >>>> and hence the interface is intended to be fully compatible. >>>> >>>> A per-cpu array of cache information maintained is used mainly for >>>> sysfs-related book keeping. >>>> >>>> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx> >>>> --- >>>> drivers/base/Makefile | 2 +- >>>> drivers/base/cacheinfo.c | 296 ++++++++++++++++++++++++++++++++++++++++++++++ >>>> include/linux/cacheinfo.h | 43 +++++++ >>>> 3 files changed, 340 insertions(+), 1 deletion(-) >>>> create mode 100644 drivers/base/cacheinfo.c >>>> create mode 100644 include/linux/cacheinfo.h >>>> >>>> diff --git a/drivers/base/Makefile b/drivers/base/Makefile >>>> index 94e8a80..76f07c8 100644 >>>> --- a/drivers/base/Makefile >>>> +++ b/drivers/base/Makefile >>>> @@ -4,7 +4,7 @@ obj-y := core.o bus.o dd.o syscore.o \ >>>> driver.o class.o platform.o \ >>>> cpu.o firmware.o init.o map.o devres.o \ >>>> attribute_container.o transport_class.o \ >>>> - topology.o >>>> + topology.o cacheinfo.o >>>> obj-$(CONFIG_DEVTMPFS) += devtmpfs.o >>>> obj-$(CONFIG_DMA_CMA) += dma-contiguous.o >>>> obj-y += power/ >>>> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c >>>> new file mode 100644 >>>> index 0000000..f436c31 >>>> --- /dev/null >>>> +++ b/drivers/base/cacheinfo.c >>>> @@ -0,0 +1,296 @@ >>>> +/* >>>> + * cacheinfo support - processor cache information via sysfs >>>> + * >>>> + * Copyright (C) 2013 ARM Ltd. >>>> + * All Rights Reserved >>>> + * >>>> + * Author: Sudeep Holla <sudeep.holla@xxxxxxx> >>>> + * >>>> + * This program is free software; you can redistribute it and/or modify >>>> + * it under the terms of the GNU General Public License version 2 as >>>> + * published by the Free Software Foundation. >>>> + * >>>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any >>>> + * kind, whether express or implied; without even the implied warranty >>>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >>>> + * GNU General Public License for more details. >>>> + */ >>>> +#include <linux/bitops.h> >>>> +#include <linux/cacheinfo.h> >>>> +#include <linux/compiler.h> >>>> +#include <linux/cpu.h> >>>> +#include <linux/device.h> >>>> +#include <linux/init.h> >>>> +#include <linux/kobject.h> >>>> +#include <linux/of.h> >>>> +#include <linux/sched.h> >>>> +#include <linux/slab.h> >>>> +#include <linux/smp.h> >>>> +#include <linux/sysfs.h> >>>> + >>>> +struct cache_attr { >>>> + struct attribute attr; >>>> + ssize_t(*show) (unsigned int, unsigned short, char *); >>>> + ssize_t(*store) (unsigned int, unsigned short, const char *, size_t); >>>> +}; >>>> + >>>> +/* pointer to kobject for cpuX/cache */ >>>> +static DEFINE_PER_CPU(struct kobject *, ci_cache_kobject); >>>> +#define per_cpu_cache_kobject(cpu) (per_cpu(ci_cache_kobject, cpu)) >>>> + >>>> +struct index_kobject { >>>> + struct kobject kobj; >>>> + unsigned int cpu; >>>> + unsigned short index; >>>> +}; >>>> + >>>> +static cpumask_t cache_dev_map; >>>> + >>>> +/* pointer to array of kobjects for cpuX/cache/indexY */ >>> >>> Please don't use "raw" kobjects for this, use the device attribute >>> groups, that's what they are there for. Bonus is that your code should >>> get a lot simpler when you do that. >>> >> >> Yes I now understand device attribute group simplifies the code, but I think >> kobjects are still needed as we need to track both cpu and cache index. >> By reusing only cpu device kobject, we can track cpu only. > > I don't understand, you are putting things under the cpu device object, > why do you care about a "cache" kobject? > Yes though the cache attributes are under cpu objects, it's hierarchical something like: /sys/devices/system/cpu/cpu<n>/cache/index<m>/<attribute_x> <attribute_x> is unique for each pair of (cpu<n>, index<m> index is more like cache level, but with 2 indices if they are separate(I$,D$) >> One thought I have is to make cache_info structure common to all architecture >> (for now its ARM specific) and introduce kobject in that similar to ia64 >> implementation. That even eliminates lot of weak functions defined. > > Please don't use raw kobjects if at all possible, it's not good for a > variety of reasons (no userspace events, have to roll your own code, > etc.) > Yes I understand, will try to explore other feasible solutions. Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html