Re: [boost] [interprocess]why message_queue receive() will consume so much CPU resource

Subject: Re: [boost] [interprocess]why message_queue receive() will consume so much CPU resource
From: Christian Schladetsch (christian.schladetsch_at_[hidden])
Date: 2009-09-10 05:42:38

I think this is best dealt with by the OS.

On Wed, Sep 9, 2009 at 9:40 PM, <jon_zhou_at_[hidden]> wrote:

> Hi there:
>
> I think the "sched_yield" will put itself to the end of the waiting queue
> If there is no other waiting task, the program will be scheduled again
> soon.
>
> Which is the better way to receive msg?
>
> #1
> While (1)
> {
> Mq.receive(...)
> }
>
> Or
> #2
> While (1)
> {
> if (!Mq.try_receive())
>  sleep(xx)
> }
>
> I think the former can get the best throughput performance but the latter
> can get the less resource used.
>
> Any comments?
>
> Thanks
> Jon
>
>
>
> -----Original Message-----
> From: ZHOU,JON (A-China,ex2)
> Sent: Tuesday, September 08, 2009 9:55 PM
> To: ZHOU,JON (A-China,ex2); 'boost_at_[hidden]'
> Subject: RE: [interprocess]why message_queue receive() will consume so much
> CPU resource
>
> The code can trap in sched_yield (),(see below)
>
> why it still consume high CPU resource?
>
>
> (gdb) bt
> #0  0xffffe410 in __kernel_vsyscall ()
> #1  0x401b706c in sched_yield () from /lib/tls/libc.so.6
> #2  0x0804e88f in thread_yield ()
>    at
> ../boost138inst/include/boost-1_38/boost/interprocess/detail/os_thread_functions.hpp:1
> 04
> #3  0x0804c22b in
> boost::interprocess::interprocess_condition::do_timed_wait (
>    this=0x40018018, tout_enabled=false, abs_time=@0xbff77a70,
> mut=@0x40018014)
>    at
> ../boost138inst/include/boost-1_38/boost/interprocess/sync/emulation/interprocess_cond
> ition.hpp:125
> #4  0x0804bfc2 in boost::interprocess::interprocess_condition::do_wait
> (this=0x40018018,
>    mut=@0x40018014)
>    at
> ../boost138inst/include/boost-1_38/boost/interprocess/sync/emulation/interprocess_cond
> ition.hpp:70
>
> -----Original Message-----
> From: ZHOU,JON (A-China,ex2)
> Sent: Tuesday, September 08, 2009 10:21 AM
> To: boost_at_[hidden]; ZHOU,JON (A-China,ex2)
> Subject: [interprocess]why message_queue receive() will consume so much CPU
> resource
>
> Hi there
>
> I just found that message_queue::receive() or message_queue:: timed_receive
> () consume high CPU
> resource, (99% CPU) the code like the below:
>
> //create message_queue
>
> date d(2009,Sep,8); //an arbitrary date
> //construct a time by adding up some durations durations
> ptime t1(d, hours(0)+minutes(0)+seconds(1)+millisec(0));
>
>
> while (1)
> {
>  for(int i = 0; i < 100; ++i){
>    int number;
>    //mq.receive(&number, sizeof(number), recvd_size, priority);
>    mq.timed_receive(&number, sizeof(number), recvd_size, priority,t1);
>  }
> }
>
> As I know, both the receive() & timed_receive() are block method, there
> should be sleep mechanism inside. why it still need so much CPU resource?
>
> Thanks
> jon
>
>
>
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