On Tue, Jun 8, 2010 at 6:55 AM, Hiroshi DOYU <Hiroshi.DOYU@xxxxxxxxx> wrote: > From: ext Ohad Ben-Cohen <ohad@xxxxxxxxxx> > Subject: Re: [PATCH v3 4/4] omap: mailbox: convert block api to kfifo > Date: Tue, 8 Jun 2010 05:11:50 +0200 > >> Hi Deepak, >> >> On Mon, Jun 7, 2010 at 6:27 PM, Deepak Chitriki <deepak.chitriki@xxxxxx> wrote: >>>> Ohad Ben-Cohen wrote: >>>> Somewhat relevant note about mailbox performance: omap_mbox_msg_send >>>> often (i.e. when the kfifo is empty) can just send the message >>>> directly, without triggering the tasklet to do that. Applying such a >>>> change will substantially improve the mailbox performance, and will >>>> make the shift to workqueues even more reasonable. I've got a patch >>>> for that, I'll post it soon. >>>> >>> >>> tasklet is run in atomic context,so I wonder how mailbox performance will >>> increase if you switch from tasklet to workqueue? >> >> In general moving from tasklet to workqueues will probably increase >> some scheduling latencies. >> >> Nevertheless, if we'll send mailbox messages directly whenever >> possible, without triggering any deferred context, we'll be improving >> mailbox performance on average, because most of the time we will get >> rid of the scheduling latencies entirely. > > I think that this depends on the situation. > > 1) too many messages are coming, buffering and tasklet works > efficiently at onece, for good throughput. > 2) too few messages, the latency won't be a problem? Or some PM case > may be concerned. > > I guess that most of the case, we just care about the throughput of > encoding and decoding, but I am afraid that data themselves are sent > via shared memory and the traffic of mailbox message may not be so > big. I'd like to see the actual data for practical usecases. > > Does TI have some typical test pattern to measure throughput? Or Felipe? What exactly are you interested in? The amount of messages being sent on typical video encoding/decoding scenarios? My guess is that it would be one or two messages per frame (60 msgs/s tops). -- Felipe Contreras -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
