[Click] Core performance checkins
Eddie Kohler
kohler at cs.ucla.edu
Thu Feb 10 09:15:21 EST 2011
I'm very sorry about this regression... Unfortunately due to travel it's going
to hard to look at this until the weekend. I would rather not yet revert
coreperformance. Can you handle this situation?
Eddie
On 02/09/2011 05:22 AM, Beyers Cronje wrote:
> Hi Eddie,
>
> Some info that I'm sure will help debugging. I configured click
> with --enable-schedule-debugging=extra and also enabled NOTIFIERQUEUE_DEBUG
>
> It seems Unqueue gets stuck in the pending list. See the output below:
>
> read q.length
> 1000
>
> read q.notifier_state
> notifier on
> task 0x19387b0 [uq :: Unqueue] scheduled
>
> read uq.scheduled
> true /* but pending */
>
> read uq.notifier
> empty.0/1:1*
>
>
> Unqueue stays in this scheduled but pending state for an undetermined period
> of time, up to minutes some times.
>
> Any idea where I can start on fixing this bug?
>
> Beyers
>
>
> On Wed, Feb 9, 2011 at 2:52 AM, Beyers Cronje <bcronje at gmail.com
> <mailto:bcronje at gmail.com>> wrote:
>
> Update - Strange, after typing my previous email I checked again, and all
> of a sudden Unqueue was pulling packets again. Not sure if me breaking
> into Click with gdb kick-started, it again :) or if it's a intermittent issue.
>
>
> On Wed, Feb 9, 2011 at 2:41 AM, Beyers Cronje <bcronje at gmail.com
> <mailto:bcronje at gmail.com>> wrote:
>
> Hi Eddie,
>
> Since running this merge I've been experiencing issues with usermode
> multithreading. I'm using commit 9419098acbdc20837e37f3033c40661809431f8d
> I do believe the issues are related to the changes of this merged, as
> I was running the same config on pre-coreperformance merge code
> without any issues.
>
> *Simplified Config used:*
>
> fd::FromDAG(/dev/dag0) -> cl1::Classifier(12/0800) -> MarkIPHeader(14)
> -> ipc1::IPClassifier(udp port 1646);
> sfp::SFP();
> q::ThreadSafeQueue;
> log::Logger(sfp, 1800);
>
> ipc1 -> RadAccounting -> q;
> q -> uq::Unqueue -> aupcc::Counter -> sfp;
>
> StaticThreadSched(fd 0, uq 1, log 2);
>
> *Problem Description:*
> The 3 threads in the config: FromDAG and Unqueue do what their names
> indicate, and Logger has a timer that schedules its task once every
> 30min. Everything runs fine initially and then somewhere along the
> line Unqueue stops pulling packets from the queue which leads to a
> constant queue overflow. When this happens I can see FromDAG is still
> working as q.drops increases constantly, and Logger also fires away
> every 30min. Note push rate from FromDAG is quite high, but
> what RadAccounting pushes into queue is very low ~ 100pps, which means
> queue is most of the time empty and Unqueue is not scheduled.
>
> Unfortunately I didn't configure debug scheduling, which would've
> helped. I did notice Unqueue.scheduled always returned true, even
> though it never actually ran. Not sure if the following will help, gdb
> shows the following:
>
> (gdb) info threads
> 3 Thread 0x7fa422559700 (LWP 27205) 0x000000392cedb0b3 in poll ()
> from /lib64/libc.so.6
> 2 Thread 0x7fa421d58700 (LWP 27206) 0x000000392cedcee3 in select
> () from /lib64/libc.so.6
> * 1 Thread 0x7fa432cfb740 (LWP 27197) FromDAG::process_packet
> (this=0x1afc570, erf_record=0x7fa423258bf0, rlen=<value optimized
> out>) at ../elements/local/fromdag.cc:193
> (gdb) thread 2
> [Switching to thread 2 (Thread 0x7fa421d58700 (LWP 27206))]#0
> 0x000000392cedb0b3 in poll () from /lib64/libc.so.6
> (gdb) bt
> #0 0x000000392cedb0b3 in poll () from /lib64/libc.so.6
> #1 0x000000000058bc36 in Master::run_selects_poll (this=0x1afacc0,
> thread=0x1afb8b0, more_tasks=false) at ../lib/master.cc:862
> #2 0x000000000058c4ec in Master::run_selects (this=0x1afacc0,
> thread=0x1afb8b0) at ../lib/master.cc:1050
> #3 0x000000000057ddf1 in run_os (this=0x1afb8b0) at
> ../lib/routerthread.cc:447
> #4 RouterThread::driver (this=0x1afb8b0) at ../lib/routerthread.cc:568
> #5 0x0000000000556dc9 in thread_driver (user_data=<value optimized
> out>) at click.cc:414
> #6 0x000000392d206d5b in start_thread () from /lib64/libpthread.so.0
> #7 0x000000392cee4aad in clone () from /lib64/libc.so.6
> (gdb) thread 3
> [Switching to thread 3 (Thread 0x7fa422559700 (LWP 27205))]#0
> 0x000000392cedcee3 in select () from /lib64/libc.so.6
> (gdb) bt
> #0 0x000000392cedcee3 in select () from /lib64/libc.so.6
> #1 0x000000000058c4bf in Master::run_selects (this=0x1afacc0,
> thread=0x1afb7e0) at ../lib/master.cc:1015
> #2 0x000000000057ddf1 in run_os (this=0x1afb7e0) at
> ../lib/routerthread.cc:447
> #3 RouterThread::driver (this=0x1afb7e0) at ../lib/routerthread.cc:568
> #4 0x0000000000556dc9 in thread_driver (user_data=<value optimized
> out>) at click.cc:414
> #5 0x000000392d206d5b in start_thread () from /lib64/libpthread.so.0
> #6 0x000000392cee4aad in clone () from /lib64/libc.so.6
> (gdb) thread 1
> [Switching to thread 1 (Thread 0x7fa432cfb740 (LWP 27197))]#0
> 0x000000392d20ebfd in nanosleep () from /lib64/libpthread.so.0
> (gdb) bt
> #0 FromDAG::process_packet (this=0x1afc570,
> erf_record=0x7fa423258bf0, rlen=<value optimized out>) at
> ../elements/local/fromdag.cc:193
> #1 0x00000000004d6402 in FromDAG::run_task (this=0x1afc570) at
> ../elements/local/fromdag.cc:150
> #2 0x000000000057dbe6 in fire (this=0x1afb710) at
> ../include/click/task.hh:612
> #3 run_tasks (this=0x1afb710) at ../lib/routerthread.cc:410
> #4 RouterThread::driver (this=0x1afb710) at ../lib/routerthread.cc:600
> #5 0x0000000000558513 in main (argc=<value optimized out>,
> argv=<value optimized out>) at click.cc:639
>
> One thing to note, for various reasons I'm doing something very
> unclick-like with FromDAG where I allow it to block up to 10ms. For my
> specific requirements this is not a problem, but just in case it might
> affect the way the new task handling operates it's worth noting.
>
> Beyers
>
> On Sun, Feb 6, 2011 at 1:23 AM, Eddie Kohler <kohler at cs.ucla.edu
> <mailto:kohler at cs.ucla.edu>> wrote:
>
> Hi all,
>
> This is just a note to say that I've merged the "coreperformance"
> branch
> with master. There are several changes that may speed up particularly
> simple configurations, and that (more importantly) may make it
> easier to
> experiment with different multithreading setups. (For instance I
> believe switching a task from one thread to another is faster
> now.) Let
> me know if you experience any problems
>
> Eddie
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