Konstantin Prokazoff kprokazov at svr.kiev.ua
Tue Nov 22 09:59:25 GMT 2005

Now, have checking non-FAST handler. Have some interest moments, such as
error codes, like:
Short write: 0/15 (Programming error)
Write to 137 (fdno) failed: Programming error
Maybe server becomes overloaded? (4xE1, Xeon 3G)

Best regards,
        Konstantin Prokazoff
Center Of Excellence, S_V_R Ltd., Kyiv HQs, Ukraine
Official business-partner & DevConnect member of Avaya Inc.
Regional development & support center of Digium Inc.
Tel. +38 044 594 1781, ext. 1038
Fax. +38 044 234 0455

----- Original Message ----- 
From: "John Baldwin" <jhb at freebsd.org>
To: <freebsd-hackers at freebsd.org>
Cc: "Konstantin Prokazoff" <kprokazov at svr.kiev.ua>
Sent: Monday, November 21, 2005 5:38 PM
Subject: Re: poll()/select()

> On Monday 21 November 2005 08:14 am, Konstantin Prokazoff wrote:
> > Thanks for comment,
> >
> >     I think, after kernel inspection, problem (maybe) in preemption.
> > syscall to poll or select holds sellock, and if another thread (process)
> > tries to syscall or we have taken interrupt (where handler use
> > selrecord/selwakeup too), kernel will deadlock.
> >     I have this situation cause to INTR_FAST interrupt handler in device
> > driver for Digium's PCI board, which provides 4 T1/E1 interfaces.
> > 100% repetitive.
> >     Another way to avoid such deadlock - provide different
> > for select/poll mechanism.
> You can't call selwakeup() from an INTR_FAST handler.  Try removing
> and see if it fixes your issue.  If you want to use INTR_FAST, then
> that you can only use spin mutexes in your handler, and that any more
> complicated work like selwakeup() that uses regular mutexes will have to
> deferred either by using a swi handler or dispatching a task to the Fast
> taskqueue.
> -- 
> John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
> "Power Users Use the Power to Serve"  =  http://www.FreeBSD.org

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