Report the data capacity of all ftrace ring buffers through a new Ftrace field in /proc/meminfo. Include the main and snapshot buffers of the global trace array and all tracing instances, while leaving ring-buffer metadata accounted for by Slab.
Keep the interface as a no-op when tracing is disabled so /proc/meminfo does not gain a configuration dependency on tracing. Tested on arm64 QEMU: CONFIG_TRACING=n: 0 kB Global resize/restore: 7 -> 4099 -> 7 kB Instance and snapshot lifecycle: 15 -> 1434 -> 2836 -> 1434 -> 15 kB Signed-off-by: Xiang Gao <[email protected]> --- fs/proc/meminfo.c | 3 +++ include/linux/trace.h | 5 +++++ kernel/trace/trace.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 38 insertions(+) diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c index b2813ff13cb2..96a38ffc4e35 100644 --- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -18,6 +18,7 @@ #include <linux/cma.h> #endif #include <linux/zswap.h> +#include <linux/trace.h> #include <asm/page.h> #include "internal.h" @@ -108,6 +109,8 @@ static int meminfo_proc_show(struct seq_file *m, void *v) show_val_kb(m, "Slab: ", sreclaimable + sunreclaim); show_val_kb(m, "SReclaimable: ", sreclaimable); show_val_kb(m, "SUnreclaim: ", sunreclaim); + seq_printf(m, "Ftrace: %8lu kB\n", + ftrace_buffer_total_size() >> 10); seq_printf(m, "KernelStack: %8lu kB\n", global_node_page_state(NR_KERNEL_STACK_KB)); #ifdef CONFIG_SHADOW_CALL_STACK diff --git a/include/linux/trace.h b/include/linux/trace.h index 7eaad857dee0..f9935231560c 100644 --- a/include/linux/trace.h +++ b/include/linux/trace.h @@ -53,6 +53,7 @@ int trace_array_init_printk(struct trace_array *tr); void trace_array_put(struct trace_array *tr); struct trace_array *trace_array_get_by_name(const char *name, const char *systems); int trace_array_destroy(struct trace_array *tr); +unsigned long ftrace_buffer_total_size(void); /* For osnoise tracer */ int osnoise_arch_register(void); @@ -92,6 +93,10 @@ static inline int trace_array_destroy(struct trace_array *tr) { return 0; } +static inline unsigned long ftrace_buffer_total_size(void) +{ + return 0; +} #endif /* CONFIG_TRACING */ #endif /* _LINUX_TRACE_H */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 01a5e87af299..f0bb553e3688 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5769,6 +5769,36 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf, return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); } +static unsigned long trace_array_buffer_size(struct array_buffer *buf) +{ + unsigned long size = 0; + int cpu; + + if (!buf->buffer) + return 0; + + for_each_tracing_cpu(cpu) + size += ring_buffer_size(buf->buffer, cpu); + + return size; +} + +unsigned long ftrace_buffer_total_size(void) +{ + struct trace_array *tr; + unsigned long size = 0; + + guard(mutex)(&trace_types_lock); + list_for_each_entry(tr, &ftrace_trace_arrays, list) { + size += trace_array_buffer_size(&tr->array_buffer); +#ifdef CONFIG_TRACER_SNAPSHOT + size += trace_array_buffer_size(&tr->snapshot_buffer); +#endif + } + + return size; +} + #define LAST_BOOT_HEADER ((void *)1) static void *l_next(struct seq_file *m, void *v, loff_t *pos) -- 2.34.1
