/* * udelay() test kernel module * * Test is executed by writing and reading to /sys/kernel/debug/udelay_test * Tests are configured by writing: USECS ITERATIONS * Tests are executed by reading from the same file. * Specifying usecs of 0 or negative values will run multiples tests. * * Copyright (C) 2014 Google, Inc. * * This software is licensed under the terms of the GNU General Public * License version 2, as published by the Free Software Foundation, and * may be copied, distributed, and modified under those terms. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include #include #include #include #define DEFAULT_ITERATIONS 100 #define DEBUGFS_FILENAME "udelay_test" static DEFINE_MUTEX(udelay_test_lock); static struct dentry *udelay_test_debugfs_file; static int udelay_test_usecs; static int udelay_test_iterations = DEFAULT_ITERATIONS; static int udelay_test_single(struct seq_file *s, int usecs, uint32_t iters) { int min = 0, max = 0, fail_count = 0; uint64_t sum = 0; uint64_t avg; int i; /* Allow udelay to be up to 0.5% fast */ int allowed_error_ns = usecs * 5; for (i = 0; i < iters; ++i) { s64 kt1, kt2; int time_passed; kt1 = ktime_get_ns(); udelay(usecs); kt2 = ktime_get_ns(); time_passed = kt2 - kt1; if (i == 0 || time_passed < min) min = time_passed; if (i == 0 || time_passed > max) max = time_passed; if ((time_passed + allowed_error_ns) / 1000 < usecs) ++fail_count; WARN_ON(time_passed < 0); sum += time_passed; } avg = sum; do_div(avg, iters); seq_printf(s, "%d usecs x %d: exp=%d allowed=%d min=%d avg=%lld max=%d", usecs, iters, usecs * 1000, (usecs * 1000) - allowed_error_ns, min, avg, max); if (fail_count) seq_printf(s, " FAIL=%d", fail_count); seq_puts(s, "\n"); return 0; } static int udelay_test_show(struct seq_file *s, void *v) { int usecs; int iters; int ret = 0; mutex_lock(&udelay_test_lock); usecs = udelay_test_usecs; iters = udelay_test_iterations; mutex_unlock(&udelay_test_lock); if (usecs > 0 && iters > 0) { return udelay_test_single(s, usecs, iters); } else if (usecs == 0) { struct timespec64 ts; ktime_get_ts64(&ts); seq_printf(s, "udelay() test (lpj=%ld kt=%lld.%09ld)\n", loops_per_jiffy, (s64)ts.tv_sec, ts.tv_nsec); seq_puts(s, "usage:\n"); seq_puts(s, "echo USECS [ITERS] > " DEBUGFS_FILENAME "\n"); seq_puts(s, "cat " DEBUGFS_FILENAME "\n"); } return ret; } static int udelay_test_open(struct inode *inode, struct file *file) { return single_open(file, udelay_test_show, inode->i_private); } static ssize_t udelay_test_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) { char lbuf[32]; int ret; int usecs; int iters; if (count >= sizeof(lbuf)) return -EINVAL; if (copy_from_user(lbuf, buf, count)) return -EFAULT; lbuf[count] = '\0'; ret = sscanf(lbuf, "%d %d", &usecs, &iters); if (ret < 1) return -EINVAL; else if (ret < 2) iters = DEFAULT_ITERATIONS; mutex_lock(&udelay_test_lock); udelay_test_usecs = usecs; udelay_test_iterations = iters; mutex_unlock(&udelay_test_lock); return count; } static const struct file_operations udelay_test_debugfs_ops = { .owner = THIS_MODULE, .open = udelay_test_open, .read = seq_read, .write = udelay_test_write, .llseek = seq_lseek, .release = single_release, }; static int __init udelay_test_init(void) { mutex_lock(&udelay_test_lock); udelay_test_debugfs_file = debugfs_create_file(DEBUGFS_FILENAME, S_IRUSR, NULL, NULL, &udelay_test_debugfs_ops); mutex_unlock(&udelay_test_lock); return 0; } module_init(udelay_test_init); static void __exit udelay_test_exit(void) { mutex_lock(&udelay_test_lock); debugfs_remove(udelay_test_debugfs_file); mutex_unlock(&udelay_test_lock); } module_exit(udelay_test_exit); MODULE_AUTHOR("David Riley "); MODULE_LICENSE("GPL"); 5space:mode:
authorThomas Gleixner <tglx@linutronix.de>2017-01-31 23:58:38 +0100
committerIngo Molnar <mingo@kernel.org>2017-02-01 08:37:27 +0100
commitdd86e373e09fb16b83e8adf5c48c421a4ca76468 (patch)
tree55703c2ea8584e303e342090614e0aab3509ab21 /net/dccp/diag.c
parent0b3589be9b98994ce3d5aeca52445d1f5627c4ba (diff)
perf/x86/intel/rapl: Make package handling more robust
The package management code in RAPL relies on package mapping being available before a CPU is started. This changed with: 9d85eb9119f4 ("x86/smpboot: Make logical package management more robust") because the ACPI/BIOS information turned out to be unreliable, but that left RAPL in broken state. This was not noticed because on a regular boot all CPUs are online before RAPL is initialized. A possible fix would be to reintroduce the mess which allocates a package data structure in CPU prepare and when it turns out to already exist in starting throw it away later in the CPU online callback. But that's a horrible hack and not required at all because RAPL becomes functional for perf only in the CPU online callback. That's correct because user space is not yet informed about the CPU being onlined, so nothing caan rely on RAPL being available on that particular CPU. Move the allocation to the CPU online callback and simplify the hotplug handling. At this point the package mapping is established and correct. This also adds a missing check for available package data in the event_init() function. Reported-by: Yasuaki Ishimatsu <yasu.isimatu@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Stephane Eranian <eranian@google.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Fixes: 9d85eb9119f4 ("x86/smpboot: Make logical package management more robust") Link: http://lkml.kernel.org/r/20170131230141.212593966@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'net/dccp/diag.c')