[lkml]   [2004]   [Mar]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: route cache DoS testing and softirqs
    On Tue, Mar 30, 2004 at 02:22:10PM -0800, David S. Miller wrote:
    > Otherwise, keep in mind what I said, and also as Robert mentioned every
    > single local_bh_enable() is going to call do_softirq() if the count falls
    > to zero.

    I was less concerned about the do_sofitrq in local_bh_enable, since that
    runs in a scheduler-aware context, so at least the timeslice is
    definitely accounted for and it'll schedule at some point (unlike with
    an hardirq flood). Actually the length of the default timeslice matters
    too here, lowering the max timeslice to 10msec would certainly reduce
    the effect.

    call_rcu_bh will fix the local_bh_enable too. The only problem with
    call_rcu_bh is how to queue the tasklets in every cpu (an IPI sounds
    overkill at high frequency, because effectively here we're running the rcu
    callbacks in a potential fast path). OTOH if we've to add a spinlock to
    queue the tasklet, then we might as well take a spinlock in the routing
    cache in the first place (at least for this workload).
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 14:02    [W:0.028 / U:1.288 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site