Date: Tue, 23 Dec 2008 03:30:04 GMT From: Sean Bruno <sbruno@miralink.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be lost Message-ID: <200812230330.mBN3U48o014560@freefall.freebsd.org>
index | next in thread | raw e-mail
The following reply was made to PR kern/118093; it has been noted by GNATS. 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 Date: Mon, 22 Dec 2008 19:21:49 -0800 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. Seanhelp
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200812230330.mBN3U48o014560>