summaryrefslogtreecommitdiffstats
path: root/fs/ufs/inode.c
diff options
context:
space:
mode:
authorSteven Rostedt <srostedt@redhat.com>2011-06-24 23:28:13 -0400
committerSteven Rostedt <rostedt@goodmis.org>2011-07-07 22:39:38 -0400
commit4376cac66778b25e599be3f5d54f33f58ba8ead7 (patch)
tree9cf05820586f140bafcde67cd2cd80a4391ef7eb /fs/ufs/inode.c
parente4a3f541f0b67fdad98b326c851dfe7f4b6b6dad (diff)
downloadlinux-4376cac66778b25e599be3f5d54f33f58ba8ead7.tar.bz2
ftrace: Do not disable interrupts for modules in mcount update
When I mounted an NFS directory, it caused several modules to be loaded. At the time I was running the preemptirqsoff tracer, and it showed the following output: # tracer: preemptirqsoff # # preemptirqsoff latency trace v1.1.5 on 2.6.33.9-rt30-mrg-test # -------------------------------------------------------------------- # latency: 1177 us, #4/4, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4) # ----------------- # | task: modprobe-19370 (uid:0 nice:0 policy:0 rt_prio:0) # ----------------- # => started at: ftrace_module_notify # => ended at: ftrace_module_notify # # # _------=> CPU# # / _-----=> irqs-off # | / _----=> need-resched # || / _---=> hardirq/softirq # ||| / _--=> preempt-depth # |||| /_--=> lock-depth # |||||/ delay # cmd pid |||||| time | caller # \ / |||||| \ | / modprobe-19370 3d.... 0us!: ftrace_process_locs <-ftrace_module_notify modprobe-19370 3d.... 1176us : ftrace_process_locs <-ftrace_module_notify modprobe-19370 3d.... 1178us : trace_hardirqs_on <-ftrace_module_notify modprobe-19370 3d.... 1178us : <stack trace> => ftrace_process_locs => ftrace_module_notify => notifier_call_chain => __blocking_notifier_call_chain => blocking_notifier_call_chain => sys_init_module => system_call_fastpath That's over 1ms that interrupts are disabled on a Real-Time kernel! Looking at the cause (being the ftrace author helped), I found that the interrupts are disabled before the code modification of mcounts into nops. The interrupts only need to be disabled on start up around this code, not when modules are being loaded. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'fs/ufs/inode.c')
0 files changed, 0 insertions, 0 deletions