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Peter Anvin" , x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V5 08/14] trace: Add __print_ns_to_secs() and __print_ns_without_secs() helpers Date: Tue, 22 Jun 2021 16:42:26 +0200 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt To have nanosecond output displayed in a more human readable format, its nicer to convert it to a seconds format (XXX.YYYYYYYYY). The problem is that to do so, the numbers must be divided by NSEC_PER_SEC, and moded too. But as these numbers are 64 bit, this can not be done simply with '/' and '%' operators, but must use do_div() instead. Instead of performing the expensive do_div() in the hot path of the tracepoint, it is more efficient to perform it during the output phase. But passing in do_div() can confuse the parser, and do_div() doesn't work exactly like a normal C function. It modifies the number in place, and we don't want to modify the actual values in the ring buffer. Two helper functions are now created: __print_ns_to_secs() and __print_ns_without_secs() They both take a value of nanoseconds, and the former will return that number divided by NSEC_PER_SEC, and the latter will mod it with NSEC_PER_SEC giving a way to print a nice human readable format: __print_fmt("time=%llu.%09u", __print_ns_to_secs(REC->nsec_val), __print_ns_without_secs(REC->nsec_val)) Cc: Jonathan Corbet Cc: Steven Rostedt Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Alexandre Chartre Cc: Clark Willaims Cc: John Kacur Cc: Juri Lelli Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Steven Rostedt Signed-off-by: Daniel Bristot de Oliveira --- include/trace/trace_events.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h index 8268bf747d6f..acc17194c160 100644 --- a/include/trace/trace_events.h +++ b/include/trace/trace_events.h @@ -358,6 +358,21 @@ TRACE_MAKE_SYSTEM_STR(); trace_print_hex_dump_seq(p, prefix_str, prefix_type, \ rowsize, groupsize, buf, len, ascii) +#undef __print_ns_to_secs +#define __print_ns_to_secs(value) \ + ({ \ + u64 ____val = (u64)(value); \ + do_div(____val, NSEC_PER_SEC); \ + ____val; \ + }) + +#undef __print_ns_without_secs +#define __print_ns_without_secs(value) \ + ({ \ + u64 ____val = (u64)(value); \ + (u32) do_div(____val, NSEC_PER_SEC); \ + }) + #undef DECLARE_EVENT_CLASS #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \ static notrace enum print_line_t \ @@ -736,6 +751,16 @@ static inline void ftrace_test_probe_##call(void) \ #undef __print_array #undef __print_hex_dump +/* + * The below is not executed in the kernel. It is only what is + * displayed in the print format for userspace to parse. + */ +#undef __print_ns_to_secs +#define __print_ns_to_secs(val) (val) / 1000000000UL + +#undef __print_ns_without_secs +#define __print_ns_without_secs(val) (val) % 1000000000UL + #undef TP_printk #define TP_printk(fmt, args...) "\"" fmt "\", " __stringify(args) -- 2.31.1