Wow! using the legacy driver cut my DPC latency from average 100+ usecs to 25 usecs, my usual methods to reproduce raspy audio now fail. I'll have to see how things work with 192K sample rate, normal -- no freezes so far.
OS win 7 64, Quad 2.4GHz, TI firewire chipset. Dave W0DHB -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Gerald Youngblood Sent: Tuesday, June 29, 2010 11:06 AM To: Don Cc: Flex Edge Subject: Re: [FlexEdge] DPC Latency Don, Here is a recent quote from our FireWire chip vendor related to a problem in Windows 7. One of our FLEX-5000 customers works for Microsoft, knows the OHCI1394 development manager, and is trying to assist from the inside. This problem can cause distorted or "raspy" audio on some hardware configurations. We don't have any systems here that exhibit that problem but it can exist. The short term solution is to use the legacy driver mode as noted below. [BEGIN QUOTE] * * *Windows 7 Known Issue* Microsoft introduced a new 1394 OHCI bus driver in Windows 7. We have made several fixes in this release to improve performance when using this new bus driver. We have also added a workaround to the driver to avoid an intermittent BSOD in Microsoft's new OHCI bus driver when using Windows 7 64-bit on quad-core processors. Even after these changes we still found that the CPU usage is significantly higher when using the new 1394 OHCI bus driver on Windows 7. Upon investigation we have found a serious regression in Microsoft's new 1394 OHCI bus driver that is the source of this increased CPU usage (technical details: it is processing an interrupt and a DPC for every isochronous packet that is sent or received). We have not been able to find a way to work around this issue. We have also tested several other third-party 1394 products that use isochronous streaming and this issue occurs with all of them. We have reported this issue to Microsoftand are working with a 1394 support engineer who is currently investigating it. If this additional CPU overhead is an issue for users, they will have to use Microsoft's legacy 1394 OHCI bus driver until we either have a workaround or a hot-fix for this issue from Microsoft. We will send out additional information on this issue once we receive an official response from Microsoft. [END QUOTE] Regards, Gerald Gerald Youngblood, K5SDR President and CEO FlexRadio Systems(TM) 13091 Pond Springs Road, #250 Austin, TX 78729 Phone: 512-535-4713 Ext. 202 Email: [email protected] Web: www.flex-radio.com Tune In Excitement (TM) PowerSDR(TM) is a trademark of FlexRadio Systems On Tue, Jun 29, 2010 at 1:06 AM, Don <[email protected]> wrote: > Hello, > > Well installed Win Pro -7 64 bit about two weeks ago. > > I have noticed a couple of thins, my DPC use to average around 60-80 with > just PowerSDR running. Now it's around 300-400. > I also noticed that my CPU usage has almost tripled from around 2-5 % to > 12-17 %. It dose not seem to bother performance so it's mostly > a curiosity to me. For those of you who know (not me) dose Win 7 really > use that much more overhead? > > Anyway still having fun. > > Don kd6hq > _______________________________________________ > Flexedge mailing list > [email protected] > http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz > This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used > for posting topics related to SDR software development and experimentalist > who are using alpha and beta versions of the software. > _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using alpha and beta versions of the software. _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using alpha and beta versions of the software.
