Re: [PATCH v2 2/3] Timekeeping: Resolving Route Dependencies

[Stefano Brivio <sbrivio@redhat.com>]

On Tue,  8 Sep 2026 18:13:13 +0000
Martin Schitter <ms+git@mur.at> wrote:

> ---
>  netlink.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/netlink.c b/netlink.c
> index 650a6fd..65cc5d7 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -18,6 +18,7 @@
>  #include <errno.h>
>  #include <sys/types.h>
>  #include <limits.h>
> +#include <time.h>
>  #include <unistd.h>
>  #include <signal.h>
>  #include <stdlib.h>
> @@ -604,6 +605,7 @@ int nl_route_dup(int s_src, unsigned int ifi_src,
>  	char buf[NLBUFSIZ * 8];
>  	uint32_t seq;
>  	unsigned i;
> +	struct timespec start, now;
>  
>  	seq = nl_send(s_src, &req, RTM_GETROUTE, NLM_F_DUMP, sizeof(req));
>  
> @@ -706,6 +708,7 @@ int nl_route_dup(int s_src, unsigned int ifi_src,
>  	 * can safely ignore that and repeat the requests. This avoids the need
>  	 * to calculate dependencies: let the kernel do that.
>  	 */
> +	clock_gettime(CLOCK_MONOTONIC, &start);

This adds overhead (even if minimal) in a general case, but it's only
used for debug() messages.

>  	for (i = 0; i < dup_routes; i++) {
>  		for (nh = (struct nlmsghdr *)buf, left = nlmsgs_size;
>  		     NLMSG_OK(nh, left);
> @@ -724,6 +727,9 @@ int nl_route_dup(int s_src, unsigned int ifi_src,
>  				return rc;
>  		}
>  	}
> +	clock_gettime(CLOCK_MONOTONIC, &now);
> +	debug("route dependency handling time: %f s",
> +	    (now.tv_sec - start.tv_sec) + (now.tv_nsec - start.tv_nsec)/1.0e9);

And anyway, I'm not sure I see the value of this. Which other functions
should we profile? Does it help at all to do this once you're done
developing it?

I would suggest to simply drop this patch. I understand you needed that
for development but you already explain in the commit message for 3/3
how it improves thing, and that's all the documentation we possibly
need for the future, I think.

>  
>  	return 0;
>  }

-- 
Stefano