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#! /usr/bin/env stap
/*
* Copyright (C) 2009 Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License v.2.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* Description: displays which task is holding big kernel lock (BKL) when the
* number of waiting processes reaches a certain number.
*
* Run: stap bkl.stp <number_of_processes_waiting>
*
* Author: Flavio Leitner <fbl@redhat.com>
*/
# how many tasks waiting on big lock
global waiting = 0
# who is holding big lock
global holder = 0
global holder_time
probe begin { printf("stap ready\n"); }
probe end { printf("stap exiting\n"); }
probe kernel.function("lock_kernel") {
++waiting;
}
probe kernel.function("lock_kernel").return {
# under biglock
holder_time = gettimeofday_us();
holder = task_current();
--waiting;
}
probe kernel.function("unlock_kernel") {
# under biglock
if (waiting >= $1) {
printf("%-25s: waiting(%d), holder: %s(%d) %dus\n",
ctime(gettimeofday_s()),
waiting,
task_execname(holder),
task_pid(holder),
gettimeofday_us() - holder_time);
}
}
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