RE: [PATCH B 3/3] tidspbridge: decreate timeout to a saner value

From: "Guzman Lugo, Fernando" <x0095840@ti.com>
To: Felipe Contreras <felipe.contreras@gmail.com>
Cc: "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
	"Kanigeri, Hari" <h-kanigeri2@ti.com>,
	Hiroshi DOYU <hiroshi.doyu@nokia.com>,
	Ameya Palande <ameya.palande@nokia.com>,
	Felipe Contreras <felipe.contreras@nokia.com>
Subject: RE: [PATCH B 3/3] tidspbridge: decreate timeout to a saner value
Date: Thu, 19 Mar 2009 19:00:34 -0500	[thread overview]
Message-ID: <496565EC904933469F292DDA3F1663E60287D628DC@dlee06.ent.ti.com> (raw)
In-Reply-To: <94a0d4530903191435g7785a334v6e0a6988f344bbc@mail.gmail.com>

This is a stress test, it creates 4 processes and each process will do 1000 transfers using streams, so the trace is:

STRM_Issue ->  WMD_CHNL_AddIOReq  -> IO_Schedule

IO_Schedule schedules a call to IO_DPC using task let.

IO_DPC -> IO_DispatchChnl -> InputChnl -> CHNLSM_InterruptDSP2

Also      IO_DispatchChnl -> OutputChnl -> CHNLSM_InterruptDSP2.

As we can call a lot CHNLSM_InterruptDSP2 in this test, there is a problem with the timeout. However running other tests, videos and mp3 there no problems. I think we should change to 10ms, only to make sure there is no problem when CHNLSM_InterruptDSP2 is called a lot.

Let me know if you are agreed. Or have some comments about it.

Regards,
Fernando.

-----Original Message-----
From: Felipe Contreras [mailto:felipe.contreras@gmail.com] 
Sent: Thursday, March 19, 2009 3:35 PM
To: Guzman Lugo, Fernando
Cc: linux-omap@vger.kernel.org; Kanigeri, Hari; Hiroshi DOYU; Ameya Palande; Felipe Contreras
Subject: Re: [PATCH B 3/3] tidspbridge: decreate timeout to a saner value

On Thu, Mar 19, 2009 at 11:19 PM, Guzman Lugo, Fernando <x0095840@ti.com> wrote:
>
> Yes, I applied this; in fact I have applied all the patches. If I increase the timeout there are no problems. The test I run creates 4 process and each one does several a lot of calls to InputChnl and OutputChnl, so I think this test is using the mailbox a lot and would be better a bigger timeout. What do you think?

How fast are these messages sent? Can you track down which functions
are calling CHNLSM_InterruptDSP2 and making these timeouts happen.

I think it's safe to leave the timeout at 10, but that means it's
possible the code will be busy-looping up to 10 ms which will increase
the CPU load. Somebody from Nokia (Siarhei?) suggested to idle-wait
for the mbox empty irq, I think that's the best way to implement this,
but at least for the use cases I'm interested in (video
encoding/decoding) timeouts don't seem to be an issue anymore.

-- 
Felipe Contreras