Date: Fri, 1 Feb 2008 13:57:09 -0000 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Steven Hartland" <killing@multiplay.co.uk>, "Eric Anderson" <anderson@freebsd.org> Cc: Dieter <freebsd@sopwith.solgatos.com>, freebsd-performance@freebsd.org Subject: Re: newfs locks entire machine for 20seconds Message-ID: <018701c864da$57020f20$b6db87d4@multiplay.co.uk> References: <200801310147.BAA04522@sopwith.solgatos.com><47A2A606.9080702@freebsd.org><002201c86499$7861ac20$b6db87d4@multiplay.co.uk><47A30EA7.7050506@freebsd.org> <016401c864d6$73251c50$b6db87d4@multiplay.co.uk>
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----- Original Message -----
From: "Steven Hartland" <killing@multiplay.co.uk>
> ----- Original Message -----
> From: "Eric Anderson" <anderson@freebsd.org>
>> Wait - if it returns EAGAIN for a while, then look at that code above.
>> It will hold the sysctl lock for some indefinite amount of time. Maybe
>> it should look like this instead:
>>
>>
>> do {
>> SYSCTL_LOCK();
>> req.oldidx = 0;
>> req.newidx = 0;
>> error = sysctl_root(0, name, namelen, &req);
>> SYSCTL_UNLOCK();
>> } while (error == EAGAIN);
>>
>> if (req.lock == REQ_WIRED && req.validlen > 0)
>> vsunlock(req.oldptr, req.validlen);
>>
>
> Tried no difference unfortunately, possibly its give the closeness
> of the lock unlock its just reacquiring the lock straight after releasing
> it hence not giving the other thread chance to run / obtain the lock?
In an attempt to prove this is in fact the issue I've tried with the
locking around this code removed, yes dangerous but just as a test :)
It does indeed prevent the extended lockup so this is the right area.
Regards
Steve
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