When debugging or examining the performance of a system it can be useful to examine the effect of L2 prefetching. Provide an optional debugfs entry to allow a user to enable or disable L2 prefetching.
Signed-off-by: Paul Burton <[email protected]> --- arch/mips/Kconfig.debug | 10 ++++++ arch/mips/mm/Makefile | 1 + arch/mips/mm/sc-debugfs.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 92 insertions(+) create mode 100644 arch/mips/mm/sc-debugfs.c diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug index e250524..d1962cb 100644 --- a/arch/mips/Kconfig.debug +++ b/arch/mips/Kconfig.debug @@ -113,4 +113,14 @@ config SPINLOCK_TEST help Add several files to the debugfs to test spinlock speed. +config SCACHE_DEBUGFS + bool "L2 cache debugfs entries" + depends on DEBUG_FS + help + Enable this to allow parts of the L2 cache configuration, such as + whether or not prefetching is enabled, to be exposed to userland + via debugfs. + + If unsure, say N. + endmenu diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile index 67ede4e..b4c64bd 100644 --- a/arch/mips/mm/Makefile +++ b/arch/mips/mm/Makefile @@ -28,3 +28,4 @@ obj-$(CONFIG_IP22_CPU_SCACHE) += sc-ip22.o obj-$(CONFIG_R5000_CPU_SCACHE) += sc-r5k.o obj-$(CONFIG_RM7000_CPU_SCACHE) += sc-rm7k.o obj-$(CONFIG_MIPS_CPU_SCACHE) += sc-mips.o +obj-$(CONFIG_SCACHE_DEBUGFS) += sc-debugfs.o diff --git a/arch/mips/mm/sc-debugfs.c b/arch/mips/mm/sc-debugfs.c new file mode 100644 index 0000000..5eefe32 --- /dev/null +++ b/arch/mips/mm/sc-debugfs.c @@ -0,0 +1,81 @@ +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Paul Burton <[email protected]> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#include <asm/bcache.h> +#include <asm/debug.h> +#include <asm/uaccess.h> +#include <linux/debugfs.h> +#include <linux/init.h> + +static ssize_t sc_prefetch_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + bool enabled = bc_prefetch_is_enabled(); + char buf[3]; + + buf[0] = enabled ? 'Y' : 'N'; + buf[1] = '\n'; + buf[2] = 0; + + return simple_read_from_buffer(user_buf, count, ppos, buf, 2); +} + +static ssize_t sc_prefetch_write(struct file *file, + const char __user *user_buf, + size_t count, loff_t *ppos) +{ + char buf[32]; + ssize_t buf_size; + bool enabled; + int err; + + buf_size = min(count, sizeof(buf) - 1); + if (copy_from_user(buf, user_buf, buf_size)) + return -EFAULT; + + buf[buf_size] = '\0'; + err = strtobool(buf, &enabled); + if (err) + return err; + + if (enabled) + bc_prefetch_enable(); + else + bc_prefetch_disable(); + + return count; +} + +static const struct file_operations sc_prefetch_fops = { + .open = simple_open, + .llseek = default_llseek, + .read = sc_prefetch_read, + .write = sc_prefetch_write, +}; + +static int __init sc_debugfs_init(void) +{ + struct dentry *dir, *file; + + if (!mips_debugfs_dir) + return -ENODEV; + + dir = debugfs_create_dir("l2cache", mips_debugfs_dir); + if (IS_ERR(dir)) + return PTR_ERR(dir); + + file = debugfs_create_file("prefetch", S_IRUGO | S_IWUSR, dir, + NULL, &sc_prefetch_fops); + if (IS_ERR(file)) + return PTR_ERR(file); + + return 0; +} +late_initcall(sc_debugfs_init); -- 2.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
