Date: Mon, 22 Dec 2008 19:21:49 -0800 From: Sean Bruno <sbruno@miralink.com> To: Dieter <freebsd@sopwith.solgatos.com> Cc: freebsd-firewire@freebsd.org, bug-followup@freebsd.org Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be lost Message-ID: <4950594D.50208@miralink.com> In-Reply-To: <200812210524.FAA02070@sopwith.solgatos.com> References: <200812210524.FAA02070@sopwith.solgatos.com>
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Dieter wrote: > In message <494DAEB1.1070909@miralink.com>, Sean Bruno writes: > > >> I setup my system to execute a bus reset every 1 second, simultaneously, >> I started copying a large >> file onto the system see if anything would happen. >> >> I saw no change to copy speed reported by SCP during the entire >> transaction. I also see no change >> to the system load while this is occurring. >> > > Does your system have a RS-232 console or VGA console? > The problem might be specific to RS-232. > > I have both. I disabled my serial console to test, no change when using the VGA console only. >> This seems indicative of "something else" going on. >> > > Any idea what this "something else" might be? > > Does anyone have a clue why my spl calls are returning 0 ? > > I confirmed that spl's are complete no-ops since rel 5. So, you want to ignore them as they are just markers now where locking should be implemented. I went back in your original submission and I can see a significant drop in I/O when resetting the F/W bus. If I have the following running: dd if=/dev/zero of=/dev/ad6 bs=64k Then I see about 64MB/S normally. When I reset any firewire bus, I see the throughput drop as reported by iostat by a significant amount(2-4 MB/s). I am assuming that the firewire driver is holding a very heavy lock here that is cascading down to the printf(). At least, that would be my ASSumption. :) I will continue to poke around. You are not crazy Dieter. Sean
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