LinuxQuestions.org
Latest LQ Deal: Complete CCNA, CCNP & Red Hat Certification Training Bundle
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - General
User Name
Password
Linux - General This Linux forum is for general Linux questions and discussion.
If it is Linux Related and doesn't seem to fit in any other forum then this is the place.

Notices


Reply
  Search this Thread
Old 05-03-2012, 10:25 AM   #1
pbu
LQ Newbie
 
Registered: May 2012
Posts: 1

Rep: Reputation: Disabled
What causes ftrace irqsoff to show long latency on spin_lock?


Am I reading this wrong? Is this really 12ms to acquire a spin_lock? What could cause this?

mpstat shows about 48% of time spent in softirqs

Please help me understand what might cause this.

Just switched from an older kernel version where didn't have this issue.




# tracer: irqsoff
#
irqsoff latency trace v1.1.5 on 2.6.27
--------------------------------------------------------------------
latency: 12217 us, #12/12, CPU#6 | (M:server VP:0, KP:0, SP:0 HP:0 #P:8)
-----------------
| task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------
=> started at: __wake_up_sync+0x2e/0x70 <ffffffff8023280e>
=> ended at: __wake_up_sync+0x55/0x70 <ffffffff80232835>

<idle> 0 6 11 00000000 00000000 [d3174fac] 0.000ms (+0.000ms): _spin_lock_irqsave+0x22/0x50 <ffffffff806deca2> (__wake_up_sync+0x2e/0x70 <ffffffff8023280e>)
<idle> 0 6 11 00000000 00000001 [d3174fac] 0.000ms (+0.000ms): ep_poll_callback+0x14/0xf0 <ffffffff802dfbe4> (__wake_up_common+0x5a/0x90 <ffffffff8023126a>)
<idle> 0 6 11 00000000 00000002 [d3174fac] 0.000ms (+0.000ms): _spin_lock_irqsave+0x11/0x50 <ffffffff806dec91> (ep_poll_callback+0x29/0xf0 <ffffffff802dfbf9>)
<idle> 0 6 11 00000000 00000003 [d3174fac] 0.000ms (+12.218ms): _spin_lock+0x4/0x20 <ffffffff806de864> (task_rq_lock+0x54/0xa0 <ffffffff802329f4>)
<idle> 0 6 11 00000000 00000004 [d3177f66] 12.218ms (+0.000ms): native_smp_send_reschedule+0x4/0x60 <ffffffff8021f944> (resched_task+0x68/0x80 <ffffffff80230648>)
<idle> 0 6 11 00000000 00000005 [d3177f66] 12.218ms (+0.000ms): flat_send_IPI_mask+0x14/0xa0 <ffffffff80225b04> (native_smp_send_reschedule+0x3f/0x60 <ffffffff8021f97f>)
<idle> 0 6 11 00000000 00000006 [d3177f66] 12.218ms (+0.000ms): apic_wait_icr_idle+0x4/0x30 <ffffffff80220244> (flat_send_IPI_mask+0x31/0xa0 <ffffffff80225b21>)
<idle> 0 6 11 00000000 00000007 [d3177f66] 12.218ms (+0.000ms): _spin_unlock_irqrestore+0x9/0x40 <ffffffff806deb19> (try_to_wake_up+0x134/0x1f0 <ffffffff80237594>)
<idle> 0 6 11 00000000 00000008 [d3177f66] 12.218ms (+0.000ms): _spin_unlock_irqrestore+0x9/0x40 <ffffffff806deb19> (ep_poll_callback+0x40/0xf0 <ffffffff802dfc10>)
<idle> 0 6 11 00000000 00000009 [d3177f66] 12.218ms (+0.000ms): _spin_unlock_irqrestore+0x9/0x40 <ffffffff806deb19> (__wake_up_sync+0x55/0x70 <ffffffff80232835>)
<idle> 0 6 11 00000000 0000000a [d3177f66] 12.218ms (+0.000ms): _spin_unlock_irqrestore+0x1d/0x40 <ffffffff806deb2d> (__wake_up_sync+0x55/0x70 <ffffffff80232835>)
<idle> 0 6 11 00000000 0000000b [d3177f66] 12.218ms (+0.000ms): trace_hardirqs_on+0x10e/0x140 <ffffffff8027d15e> (__wake_up_sync+0x55/0x70 <ffffffff80232835>)
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
spin_lock & webcam problem DebianUser Linux - Hardware 7 02-04-2011 08:01 AM
How to enable more tracers in ftrace stella0302 Linux - Kernel 0 10-07-2009 09:02 AM
FTrace paolorallo Linux - Kernel 1 03-21-2009 11:25 PM
KDE 3.3.0 file manager doesn't show long filenames grayswander Linux - General 2 11-06-2004 06:50 AM
Having trouble with spin_lock in omnibook.o kernel module eggs Linux - Software 0 01-20-2003 10:00 PM

LinuxQuestions.org > Forums > Linux Forums > Linux - General

All times are GMT -5. The time now is 10:40 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration