Date: Tue, 16 Dec 2008 06:10:04 GMT From: Warner Losh <imp@bsdimp.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be lost Message-ID: <200812160610.mBG6A4we085419@freefall.freebsd.org>
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The following reply was made to PR kern/118093; it has been noted by GNATS.
From: Warner Losh <imp@bsdimp.com>
To: freebsd@sopwith.solgatos.com
Cc: freebsd-firewire@FreeBSD.org, freebsd-drivers@FreeBSD.org,
bug-followup@FreeBSD.org
Subject: Re: kern/118093: firewire bus reset hogs CPU, causing data to be
lost
Date: Mon, 15 Dec 2008 23:01:30 -0700 (MST)
> I found the source of this problem. When a firewire bus resets,
> the firewire driver prints a few lines to the console,
> using printf(9) and device_printf(9). I suspect that these are
> running at splfw aka splimp, locking out other i/o.
This can't be the case. There's no SPL involved at all. Maybe
removing the printfs causes an interrupt to be serviced faster,
resulting in what appears to be better performance...
> Commenting out the *printf() calls fixes the problem, but that
> isn't a good solution.
>
> Would changing the *printf() calls to log(9) calls be safe?
> ("safe" meaning other i/o doesn't get locked out)
>
> Ah, for the good old days when 19200 baud seemed fast...
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