netdev - Re: [PATCH iproute2-next 1/3] tc: support conversions to or from 64 bit nanosecond-based time

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Date:   Sun, 12 Aug 2018 16:09:08 -0600
From:   David Ahern <dsahern@...il.com>
To:     Yousuk Seung <ysseung@...gle.com>, netdev@...r.kernel.org
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        Michael McLennan <nefario@...gle.com>,
        Priyaranjan Jha <priyarjha@...gle.com>,
        Dave Taht <dave.taht@...il.com>,
        Neal Cardwell <ncardwell@...gle.com>
Subject: Re: [PATCH iproute2-next 1/3] tc: support conversions to or from 64
 bit nanosecond-based time

On 8/6/18 11:09 AM, Yousuk Seung wrote:
> diff --git a/tc/tc_core.h b/tc/tc_core.h
> index 1dfa9a4f773b..a0fe0923d171 100644
> --- a/tc/tc_core.h
> +++ b/tc/tc_core.h
> @@ -7,6 +7,10 @@
>  
>  #define TIME_UNITS_PER_SEC	1000000
>  
> +#define NSEC_PER_USEC 1000
> +#define NSEC_PER_MSEC 1000000
> +#define NSEC_PER_SEC 1000000000LL
> +

These are not specific to tc so a header in include is a better location
(utils.h or a new one)

>  enum link_layer {
>  	LINKLAYER_UNSPEC,
>  	LINKLAYER_ETHERNET,
> diff --git a/tc/tc_util.c b/tc/tc_util.c
> index d7578528a31b..c39c9046dcae 100644
> --- a/tc/tc_util.c
> +++ b/tc/tc_util.c

Similarly for these time functions - not specific to tc so move to
lib/utils.c

> @@ -385,6 +385,61 @@ char *sprint_ticks(__u32 ticks, char *buf)
>  	return sprint_time(tc_core_tick2time(ticks), buf);
>  }
>  
> +/* 64 bit times are represented internally in nanoseconds */
> +int get_time64(__s64 *time, const char *str)

__u64 seems more appropriate than __s64

> +{
> +	double nsec;
> +	char *p;
> +
> +	nsec = strtod(str, &p);
> +	if (p == str)
> +		return -1;
> +
> +	if (*p) {
> +		if (strcasecmp(p, "s") == 0 ||
> +		    strcasecmp(p, "sec") == 0 ||
> +		    strcasecmp(p, "secs") == 0)
> +			nsec *= NSEC_PER_SEC;
> +		else if (strcasecmp(p, "ms") == 0 ||
> +			 strcasecmp(p, "msec") == 0 ||
> +			 strcasecmp(p, "msecs") == 0)
> +			nsec *= NSEC_PER_MSEC;
> +		else if (strcasecmp(p, "us") == 0 ||
> +			 strcasecmp(p, "usec") == 0 ||
> +			 strcasecmp(p, "usecs") == 0)
> +			nsec *= NSEC_PER_USEC;
> +		else if (strcasecmp(p, "ns") == 0 ||
> +			 strcasecmp(p, "nsec") == 0 ||
> +			 strcasecmp(p, "nsecs") == 0)

strncasecmp would be more efficient

> +			nsec *= 1;
> +		else
> +			return -1;
> +	}
> +
> +	*time = nsec;
> +	return 0;
> +}
> +
> +void print_time64(char *buf, int len, __s64 time)
> +{
> +	double nsec = time;
> +
> +	if (time >= NSEC_PER_SEC)
> +		snprintf(buf, len, "%.3fs", nsec/NSEC_PER_SEC);
> +	else if (time >= NSEC_PER_MSEC)
> +		snprintf(buf, len, "%.3fms", nsec/NSEC_PER_MSEC);
> +	else if (time >= NSEC_PER_USEC)
> +		snprintf(buf, len, "%.3fus", nsec/NSEC_PER_USEC);
> +	else
> +		snprintf(buf, len, "%lldns", time);
> +}
> +
> +char *sprint_time64(__s64 time, char *buf)
> +{
> +	print_time64(buf, SPRINT_BSIZE-1, time);
> +	return buf;
> +}
> +
>  int get_size(unsigned int *size, const char *str)
>  {
>  	double sz;