[lkml]   [2008]   [Aug]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: loaded router, excessive getnstimeofday in oprofile
    My small IMHO regarding SO_TIMESTAMP.

    1)Right now i have 400-500 Mbps passing router. If i will run
    5 "pings" ,simultaneous ,under _USER_ privileges(i know ping is suid),
    instead of free 20% CPU time, i will have 1-2% free CPU time. Sure i know
    ping is suid program, but it is has been "like this" since long time. By
    security psychos it will be caled DoS.

    2)Usefullness of this option. What is a difference if on almost idle machine
    timestamp retrieved on higher level or lower level?
    And why we need on highly loaded server so high precision timestamp (with
    expensive timer), if in my case enabling any socket with SO_TIMESTAMP
    creating delays more than 10ms(up to 100ms)?

    3)Who is most users of SO_TIMESTAMP? iputils which is installed on almost
    _ANY_ linux machine? busybox which is using same option? Many others
    userspace multiplatform applications? Or banks? I dont take much in account
    dhcpd, who is maybe abusing this option.

    So there is few good solutions available (IMHO):
    1)Introduce some SO_REALTIMESTAMP (anyway even SO_TIMESTAMP not defined in any
    standard) for banks and ntp folks, who need them. And even give them timespec
    instead timeval, so they will be even more happy with resolution.
    2)Provide sysctl,kernel boot, or even "build time" option for "banks" to have
    high resolution(and expensive) SO_TIMESTAMP.

     \ /
      Last update: 2008-08-28 18:53    [W:0.021 / U:69.648 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site