Re: Add timestamp to dpdk.log

[Soumya Muralidhar <soumya.muralidhar@gigamon.com>]

Hi Stephen,

Thanks for getting back. But I am looking at storing logs with timestamps in a file, basically something similar to syslog. Could you help me with that ?

Regards,
Soumya

On 1/5/22, 8:17 AM, "Stephen Hemminger" <stephen@networkplumber.org> wrote:

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    I use this. There was a more general version submitted as a patch to
    DPDK but no one seemed interested.  The reason for redirecting stdout
    is that are libraries we use that print to stdout and want to get timestamps
    from them if debugging startup issues.


    /*
     * Sample of redirecting DPDK log stream.
     *
     * If program is run for debugging then stdout will be a console and
     * put messages onto console stream with timestamps.  Otherwise, just
     * put message onto stderr which systemd journal handles.  No need for
     * syslog because that causes duplicate messages.
     */

    static struct timespec log_t0; /* Start program in monotonic time */

    /*
     * Write message to standard output with timestamp.
     * Use writev() so that timestamp and message do not get interleaved.
     */
    static ssize_t
    dpdk_log_tty_write(__rte_unused void *ctx, const char *buf, size_t size)
    {
            struct timespec ts;
            struct iovec iov[2];
            char tbuf[64];

            /* format up monotonic timestamp */
            clock_gettime(CLOCK_MONOTONIC, &ts);

            ts.tv_sec -= log_t0.tv_sec;
            ts.tv_nsec -= log_t0.tv_nsec;
            if (ts.tv_nsec < 0) {
                    --ts.tv_sec;
                    ts.tv_nsec += NS_PER_S;
            }

            iov[0].iov_base = tbuf;
            iov[0].iov_len  = snprintf(tbuf, sizeof(tbuf), "[%8lu.%06lu] ",
                                       ts.tv_sec, ts.tv_nsec / 1000u);

            /* extra cast is workaround to remove const qualifier */
            iov[1].iov_base = (void *)(uintptr_t)buf;
            iov[1].iov_len = size;

            return writev(STDOUT_FILENO, iov, 2);
    }

    static cookie_io_functions_t dpdk_log_tty_func = {
            .write = dpdk_log_tty_write,
    };

    /*
     * Print message to stderr with priority format so that
     * Systemd journal can handle it. Alternative would be
     * to use syslog or use sd_journal; but less is more.
     */
    static ssize_t
    dpdk_log_write(__rte_unused void *ctx, const char *buf, size_t size)
    {
            /* Syslog error levels are from 0 to 7, DPDK uses 1 to 8 */
            int priority = rte_log_cur_msg_loglevel() - 1;

            fprintf(stderr, "<%i>%.*s\n", priority, (int)size, buf);
            return size;
    }

    static cookie_io_functions_t dpdk_log_func = {
            .write = dpdk_log_write,
    };

    /*
     * Override default DPDK logging which duplicates messages
     * to both stderr and syslog.
     */
    static void log_init(void)
    {
            backplane_logtype = rte_log_register("backplane");
            if (backplane_logtype >= 0)
                    rte_log_set_level(backplane_logtype, RTE_LOG_INFO);

            if (isatty(STDOUT_FILENO)) {
                    clock_gettime(CLOCK_MONOTONIC, &log_t0);

                    stdout = fopencookie(NULL, "w+", dpdk_log_tty_func);
                    setlinebuf(stdout);
                    rte_openlog_stream(stdout);
            } else {
                    FILE *jf;

                    jf = fopencookie(NULL, "w+", dpdk_log_func);
                    rte_openlog_stream(jf);
            }
    }

    /* Put DPDK log back onto stderr */
    static void log_uninit(void)
    {
            FILE *logf;

            logf = rte_log_get_stream();
            if (logf != stderr) {
                    rte_openlog_stream(stderr);
                    fclose(logf);
            }
    }

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