lkml.org 
[lkml]   [2011]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    Subject[PATCH 0/3][RFC] trace_printk() using percpu buffers
    Peter,

    You had issues with the previous version of my trace_printk() code.
    I rewrote it to do the following.

    By default, it still uses the single buffer protected by a spinlock
    and an atomic (for NMIs). The NMI case can cause dropped prints if
    the NMI happens while a trace_printk() is processing.

    When trace_printk_percpu is enabled, either via the trace options or
    the kernel command line, then two sets of percpu buffers are made,
    one for normal and irqs (interrupts are still disabled), and the other
    is for NMIs. These can be added or removed at anytime.

    The last patch adds a CONFIG_TRACE_PRINTK_PERCPU that makes trace_printk()
    permanently use two sets of per_cpu buffers, and these can not be
    removed. This will give the least amount of overhead for trace_printk()
    with the sacrifice of memory overhead. This is an option I could imagine
    you would just set and forget about.

    Let me know your thoughts.

    Thanks,

    -- Steve


    Steven Rostedt (3):
    tracing: Do not allocate buffer for trace_marker
    tracing: Add optional percpu buffers for trace_printk()
    tracing: Add config to permanently have trace_printk() use percpu buffers

    ----
    Documentation/kernel-parameters.txt | 11 +
    kernel/trace/Kconfig | 18 ++
    kernel/trace/trace.c | 360 ++++++++++++++++++++++++++++-------
    kernel/trace/trace.h | 1 +
    4 files changed, 320 insertions(+), 70 deletions(-)
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2011-10-08 19:15    [W:0.020 / U:88.360 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site