Date: Wed, 8 Jul 2009 12:16:39 +0200 From: Piotr =?iso-8859-2?q?Zi=EAcik?= <kosmo@semihalf.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: Rafal Jaworowski <raj@semihalf.com>, freebsd-arm@freebsd.org, thompsa@freebsd.org, freebsd-usb@freebsd.org Subject: Re: CPU Cache and busdma usage in USB Message-ID: <200907081216.40100.kosmo@semihalf.com> In-Reply-To: <200907081103.45388.hselasky@c2i.net> References: <200906231035.43096.kosmo@semihalf.com> <37C51279-42D8-49DE-8249-0DA386EBB062@semihalf.com> <200907081103.45388.hselasky@c2i.net>
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Wednesday 08 July 2009 11:03:43 Hans Petter Selasky napisa=B3(a): > > And what about my patch suggestion in my previous e-mail having the same > subject. Does it work? > I have tested it and it does not work. By the way Writeback before Writebac= k=20 Invalidate did not change cache behaviour too much. Writeback invalidate=20 means flush all modified cache lines and then invalidate cache. However looking into logs which I have sent you yesterdat I see one differe= nce=20 which may be significant. My patch changes Invalidate into Writeback=20 Invalidate. In original code if driver write something to memory and then=20 invalidate cache, the write will be lost. With my patch after change will be written to memory and then cache will be invalidated. What do you think ? =2D-=20 Best Regards, Piotr Ziecik
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