/* * tracing clocks * * Copyright (C) 2009 Red Hat, Inc., Ingo Molnar * * Implements 3 trace clock variants, with differing scalability/precision * tradeoffs: * * - local: CPU-local trace clock * - medium: scalable global clock with some jitter * - global: globally monotonic, serialized clock * * Tracer plugins will chose a default from these clocks. */ #include #include #include #include #include #include #include #include /* * trace_clock_local(): the simplest and least coherent tracing clock. * * Useful for tracing that does not cross to other CPUs nor * does it go through idle events. */ u64 notrace trace_clock_local(void) { u64 clock; /* * sched_clock() is an architecture implemented, fast, scalable, * lockless clock. It is not guaranteed to be coherent across * CPUs, nor across CPU idle events. */ preempt_disable_notrace(); clock = sched_clock(); preempt_enable_notrace(); return clock; } EXPORT_SYMBOL_GPL(trace_clock_local); /* * trace_clock(): 'between' trace clock. Not completely serialized, * but not completely incorrect when crossing CPUs either. * * This is based on cpu_clock(), which will allow at most ~1 jiffy of * jitter between CPUs. So it's a pretty scalable clock, but there * can be offsets in the trace data. */ u64 notrace trace_clock(void) { return local_clock(); } EXPORT_SYMBOL_GPL(trace_clock); /* * trace_jiffy_clock(): Simply use jiffies as a clock counter. * Note that this use of jiffies_64 is not completely safe on * 32-bit systems. But the window is tiny, and the effect if * we are affected is that we will have an obviously bogus * timestamp on a trace event - i.e. not life threatening. */ u64 notrace trace_clock_jiffies(void) { return jiffies_64_to_clock_t(jiffies_64 - INITIAL_JIFFIES); } EXPORT_SYMBOL_GPL(trace_clock_jiffies); /* * trace_clock_global(): special globally coherent trace clock * * It has higher overhead than the other trace clocks but is still * an order of magnitude faster than GTOD derived hardware clocks. * * Used by plugins that need globally coherent timestamps. */ /* keep prev_time and lock in the same cacheline. */ static struct { u64 prev_time; arch_spinlock_t lock; } trace_clock_struct ____cacheline_aligned_in_smp = { .lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED, }; u64 notrace trace_clock_global(void) { unsigned long flags; int this_cpu; u64 now; local_irq_save(flags); this_cpu = raw_smp_processor_id(); now = sched_clock_cpu(this_cpu); /* * If in an NMI context then dont risk lockups and return the * cpu_clock() time: */ if (unlikely(in_nmi())) goto out; arch_spin_lock(&trace_clock_struct.lock); /* * TODO: if this happens often then maybe we should reset * my_scd->clock to prev_time+1, to make sure * we start ticking with the local clock from now on? */ if ((s64)(now - trace_clock_struct.prev_time) < 0) now = trace_clock_struct.prev_time + 1; trace_clock_struct.prev_time = now; arch_spin_unlock(&trace_clock_struct.lock); out: local_irq_restore(flags); return now; } EXPORT_SYMBOL_GPL(trace_clock_global); static atomic64_t trace_counter; /* * trace_clock_counter(): simply an atomic counter. * Use the trace_counter "counter" for cases where you do not care * about timings, but are interested in strict ordering. */ u64 notrace trace_clock_counter(void) { return atomic64_add_return(1, &trace_counter); } td colspan='2'/>context:space:mode:
authorBhumika Goyal <bhumirks@gmail.com>2017-01-25 00:54:07 +0530
committerDan Williams <dan.j.williams@intel.com>2017-01-31 18:16:30 -0800
commit970d14e3989160ee9e97c7d75ecbc893fd29dab9 (patch)
tree4a731cac4efedb17f86a912ec56c151d26792abe /net/llc/Makefile
parent7a308bb3016f57e5be11a677d15b821536419d36 (diff)
nvdimm: constify device_type structures
Declare device_type structure as const as it is only stored in the type field of a device structure. This field is of type const, so add const to declaration of device_type structure. File size before: text data bss dec hex filename 19278 3199 16 22493 57dd nvdimm/namespace_devs.o File size after: text data bss dec hex filename 19929 3160 16 23105 5a41 nvdimm/namespace_devs.o Signed-off-by: Bhumika Goyal <bhumirks@gmail.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'net/llc/Makefile')