From owner-freebsd-current  Thu Dec 20 12:41:34 2001
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Date: Thu, 20 Dec 2001 12:41:11 -0800 (PST)
From: John Baldwin <jhb@FreeBSD.org>
To: Luigi Rizzo <rizzo@aciri.org>
Subject: Re: vm_zeropage priority problems.
Cc: Peter Wemm <peter@wemm.org>, current@FreeBSD.org
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On 20-Dec-01 Luigi Rizzo wrote:
> On Thu, Dec 20, 2001 at 12:16:03PM -0800, John Baldwin wrote:
> ...
>> Priority propagation will already handle things ok.  We drop to pri_native
>> after we drop a lock (although if we still hold a contested lock we bump our
>> priority to the min(nativepri, highest priority of threads on contested
>> locks
>> we hold and drop to nativepri after dropping the last contested lock). 
> 
> ok, thanks for the clarification
> 
>> However, kthreads should tsleep() with their current priority, not PPAUSE.
> 
> "current" meaning pri_level or pri_native ? What if one tries to
> tsleep() while holding a lock and so its pri_level is raised ?

pri_level.  Calling tsleep() while holding a lock is a bug though. :)  Unless
you are calling msleep() with a lock that will be released.

> In the device polling code i did a tsleep on the "original" pri_level,
> but maybe pri_native is good enough.

pri_level is more correct.

-- 

John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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