[dpdk-dev] [dpdk-dev, 1/3] rte_interrupts: add rte_eal_intr_exit to shut down IRQ thread

[Liang, Cunming]

Hi Thomas,

Base on the previous conversation, at least it requires v2 to reword some comments.

> > >> 2. I propose to add addition comments on rte_epoll_wait() API
> > >> description. For any signal, it causes an error return, user needs
> > >> to handle.
> > > Agreed.

In addition, one conversion is not close.

> > >> the default termination handler
> > > I am not so experienced with this "default termination handler". Can
> someone
> > > clarify what it is so I could comment better about it?
> > For example, you're handling SIGINT. After finishing your necessary app
> > cleanup, then 'signal(SIGINT, SIG_DFL); raise(SIGINT);'.
> > The default signal handler can terminate the interrupt thread.

> > >> 1. Can you explain and add patch comments why default signal handler
> > >> is not good enough to terminate app.
> > > Yes if someone call tell me more about what it is so I can check it.

Thanks,
Cunming

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> Sent: Saturday, July 09, 2016 1:36 AM
> To: Liang, Cunming <cunming.liang at intel.com>
> Cc: Matthew Hall <mhall at mhcomputing.net>; dev at dpdk.org
> Subject: Re: [dpdk-dev,1/3] rte_interrupts: add rte_eal_intr_exit to shut down
> IRQ thread
> 
> Cunming, what is the status of this patchset, please?
> 
> 2016-03-23 11:24, Liang, Cunming:
> > Hi Mattew,
> >
> > Thank you for your time.
> >
> > On 3/22/2016 3:39 PM, Matthew Hall wrote:
> > > On Mon, Mar 21, 2016 at 03:58:44PM +0800, Liang, Cunming wrote:
> > >> the default termination handler
> > > I am not so experienced with this "default termination handler". Can
> someone
> > > clarify what it is so I could comment better about it?
> > For example, you're handling SIGINT. After finishing your necessary app
> > cleanup, then 'signal(SIGINT, SIG_DFL); raise(SIGINT);'.
> > The default signal handler can terminate the interrupt thread.
> >
> > >
> > >> If EINTR is caused by some non-term purpose signals, are you going
> > >> to exit the interrupt thread any way?
> > > We should discuss what makes sense here. I'm just trying to get some things
> > > working and finding EINTR was getting eaten and causing infinite looping.
> > SIGINT/SIGTERM causes EINTR return, while SIGUSR1 also can cause the
> > EINTR return. For the dedicated EAL interrupt thread, it won't be
> > expected to exit for all kinds of the cause.
> > On this view, I'm in favor of your patch which cancel the interrupt
> > thread, but don't directly return by the EINTR.
> >
> > >
> > >> Without setting 'PTHREAD_CREATE_DETACHED' won't cause the infinite
> > >> loop. However by using pthread_cancel to terminate the thread,
> > >> indeed it's necessary to set 'PTHREAD_CREATE_DETACHED'.
> > > My general understanding is that PTHREAD_CREATE_DETACHED should be
> used for
> > > any thread, which should not keep a process open by itself if it is executing,
> > > i.e. a "daemon thread". I believe the interrupt thread qualifies as such a
> > > thread if I have understood everything right (which is hard to promise when
> > > you only work in DPDK in spare time).
> > >
> > >> It looks like 'pthread_cancel' is the right way and I saw it
> > >> continue keeps current EINTR handling in EAL interrupt thread.
> > > It is one option. Depending what makes the most sense.
> > >
> > >> 1. Can you explain and add patch comments why default signal handler
> > >> is not good enough to terminate app.
> > > Yes if someone call tell me more about what it is so I can check it.
> > >
> > >> 2. I propose to add addition comments on rte_epoll_wait() API
> > >> description. For any signal, it causes an error return, user needs
> > >> to handle.
> > > Agreed.
> > >
> > >> 3. Will you do a favorite to add 'PTHREAD_CREATE_DETACHED' to all
> > >> EAL pthread too.
> > > As a spare time developer I am a bit conservative about too large of a scope
> > > and messing with code for other threads or features I didn't personally use or
> > > test. This is because I don't have the same QA resources as Intel / 6WIND /
> > > etc.. Some help from a full time developer would be great here.
> > All right, reasonable to me.
> >
> > >
> > >> Cunming
> > > Matthew.
> >
>