[Click] Core performance checkins

[Beyers Cronje]

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> 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> 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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>> click at amsterdam.lcs.mit.edu
>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>>
>
>