Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> writes: > On Sun, May 23, 2021 at 8:58 AM Alexei Starovoitov > <alexei.starovoitov@xxxxxxxxx> wrote: >> >> On Sun, May 23, 2021 at 4:48 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: >> > >> > Still wrapping my head around this, but one thing immediately sprang to >> > mind: >> > >> > > + * long bpf_timer_mod(struct bpf_timer *timer, u64 msecs) >> > > + * Description >> > > + * Set the timer expiration N msecs from the current time. >> > > + * Return >> > > + * zero >> > >> > Could we make this use nanoseconds (and wire it up to hrtimers) instead? >> > I would like to eventually be able to use this for pacing out network >> > packets, and msec precision is way too coarse for that... >> >> msecs are used to avoid exposing jiffies to bpf prog, since msec_to_jiffies >> isn't trivial to do in the bpf prog unlike the kernel. >> hrtimer would be great to support as well. >> It could be implemented via flags (which are currently zero only) >> but probably not as a full replacement for jiffies based timers. >> Like array vs hash. bpf_timer can support both. > > After reading the hrtimer code I might take the above statement back... > hrtimer looks strictly better than timerwheel and jiffies. > It scales well and there are no concerns with overload, > since sys_nanonsleep and tcp are heavy users. > So I'm thinking to drop jiffies approach and do hrtimer only. > wdyt? Oops, sorry, crossed streams, didn't see this before sending my other reply. Yeah, hrtimers only SGTM :) -Toke
