Date: Mon, 15 Dec 2008 23:01:30 -0700 (MST) 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 Message-ID: <20081215.230130.74702477.imp@bsdimp.com> In-Reply-To: <200812150330.DAA27074@sopwith.solgatos.com> References: <200812150330.DAA27074@sopwith.solgatos.com>
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> 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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