Date: Mon, 17 May 2004 13:30:45 +0200 From: "Carlos Velasco" <freebsd@newipnet.com> To: "Bruce Evans" <bde@zeta.org.au> Cc: freebsd-mobile@freebsd.org Subject: Re[5]: Modem + Network in Xircom cards, and maybe others Message-ID: <200405171330450414.08078360@192.168.128.16> In-Reply-To: <20040506151240.J19057@gamplex.bde.org> References: <200405021259230046.12648609@192.168.128.16> <200405022224250625.14440A3D@192.168.128.16> <20040505233435.B15444@gamplex.bde.org> <200405051746300245.2039F9A4@192.168.128.16> <20040506151240.J19057@gamplex.bde.org>
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On 06/05/2004 at 16:44 Bruce Evans wrote:
>On Wed, 5 May 2004, Carlos Velasco wrote:
>
>> On 06/05/2004 at 0:26 Bruce Evans wrote:
>>
>> >However, you may need only this part of it. This part permits software
>> >interrupts to be delayed by 38 ticks instead of the expected maximim
>> >of 2 ticks. I keep forgetting to fix this. Scaling by hz is not quite
Yes, this patch in sio.c seems to work perfectly. So I think sio swi is
being delayed somewhere by Giant or any other thing.
>> >right, because hz may be set to values that are too small to work all
>> >the time or even most of the time. There is a clamp to 128 (min), but
>> >this is a bit small. E.g., with hz = 1000 and speed = 115200, the
>> >original code in the above gives cp4ticks = 44 and ibufsize = 128. If
what about if we fix the value or making it adjustable via sysctl?
>The broken interrupt priorities are easy to see in "ps laxw | sort -n +4"
>output. Note that the highest priorities are numerically lowest:
> 0 27 0 0 -48 0 0 12 - WL ?? 0:00.06 (swi8:
>tty:cy+ clock)
>
> [I think this is supposed to be the low priority softclock ithread
> (the "slow" cy and sio SWIs attach to it and misname themselves as
> tty:cy and tty:sio instead of clk:cy and clk:sio). It actually has
> _highest_ priority among SWIs, so the problem is sort of the opposite
> of what I thought, but mostly worse. The "slow" cy and sio SWIs
> actually have the same bogus high priority, so they don't compete
> with other SWIs. However, they compete with softclock, and all
> other SWIs have lower priority than softclock so they don't even
> compete with it. This is the reverse of what is supposed to
> happen. I think softclock starts with the correct low priority, but
> its priority gets clobbered when the cy and sio SWIs attach to it.
>
> 0 37 0 0 -48 0 0 12 - WL ?? 0:00.00 (swi0:
>tty:cy+)
>
> [I think this is the "fast" cy and sio SWI. Verbose names which get
> truncated complicate debugging.]
I have here:
0 22 0 0 -80 0 0 12 - WL ?? 0:00.01 (irq11:
cbb0 cbb1+)
...
0 28 0 0 -48 0 0 12 - WL ?? 0:01.74 (swi8:
tty:sio clock)
0 39 0 0 -48 0 0 12 - WL ?? 0:00.00 (swi0:
tty:sio)
So, I assume you are right.
>> I believe this patch to sio.c is only a temporary solution that should
be
>> removed when GIANT dissapears in most drivers, am I right?
>
>No, it (the cp4ticks one) is a more general patch, though it is temporary
>because it is not in its final form. Best-case interrupt latency cannot
>be guaranteed for SWIs, and even a saftey margin of a factor of 4 is not
>enough even without the Giant and priority bugs, since it doesn't scale
>right when "hz" is configured to large values, and configuring "hz" to
>too-large values is now encouraged by DEVICE_POLLING.
Could we commit it or something similar?
I think sio is normal mode is broken for high speeds cause this like my
problem with modem pccard.
Regards,
Carlos Velasco
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