lkml.org 
[lkml]   [2023]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v4 1/5] tracing: Introduce faultable tracepoints
    On Mon, Nov 20, 2023 at 03:54:14PM -0500, Mathieu Desnoyers wrote:
    > When invoked from system call enter/exit instrumentation, accessing
    > user-space data is a common use-case for tracers. However, tracepoints
    > currently disable preemption around iteration on the registered
    > tracepoint probes and invocation of the probe callbacks, which prevents
    > tracers from handling page faults.
    >
    > Extend the tracepoint and trace event APIs to allow defining a faultable
    > tracepoint which invokes its callback with preemption enabled.
    >
    > Also extend the tracepoint API to allow tracers to request specific
    > probes to be connected to those faultable tracepoints. When the
    > TRACEPOINT_MAY_FAULT flag is provided on registration, the probe
    > callback will be called with preemption enabled, and is allowed to take
    > page faults. Faultable probes can only be registered on faultable
    > tracepoints and non-faultable probes on non-faultable tracepoints.
    >
    > The tasks trace rcu mechanism is used to synchronize read-side
    > marshalling of the registered probes with respect to faultable probes
    > unregistration and teardown.

    What is trace-trace rcu and why is it needed here? What's wrong with
    SRCU ?

    \
     
     \ /
      Last update: 2023-11-20 22:49    [W:4.538 / U:0.084 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site