Subject: Re: [PATCH v2 net-next] tcp: switch rtt estimations to usec resolution

From: Andi Kleen <[email-masked]>
Date: Thu, 27 Feb 2014 21:20:25 -0800

Eric Dumazet <[email-masked]> writes:
>  
> -	rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt, sack_rtt);
> +	if (first_ackt.tv64) {
> +		ktime_t curt = ktime_get_real();

Sorry I'm late to the party. One problem is that if a system doesn't use
TSC for some reason this will be incredibly slow (unfortunately this
happens for various reasons). Perhaps we need a
ktime_get_real_but_use_jiffies_if_slow() or somesuch.

-andi

-- 
[email-masked] -- Speaking for myself only