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Date:      Wed, 18 Aug 2010 12:07:09 +0400
From:      pluknet <pluknet@gmail.com>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: LOR on nfs: vfs_vnops.c:301 kern_descrip.c:1580
Message-ID:  <AANLkTimyk0ZUnHpxxJuJtTya2U3npj_5Bm8brmwHfzr3@mail.gmail.com>
In-Reply-To: <20100817160445.GO2396@deviant.kiev.zoral.com.ua>
References:  <AANLkTimJ=d06D2z24QyRQ98zEa1Pemk4=vkNGLNiX90N@mail.gmail.com> <AANLkTi=22WWy8Z5VWqri1p70iRzyocD9bWvNHwJavZ%2Bj@mail.gmail.com> <20100816185456.GU2396@deviant.kiev.zoral.com.ua> <AANLkTimfZ=UCiX9eo9XCwcROwViFCxJoB-rD1JxdAt2B@mail.gmail.com> <20100817160445.GO2396@deviant.kiev.zoral.com.ua>

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On 17 August 2010 20:04, Kostik Belousov <kostikbel@gmail.com> wrote:
> On Tue, Aug 17, 2010 at 07:42:41PM +0400, pluknet wrote:
>> 2010/8/16 Kostik Belousov <kostikbel@gmail.com>:
>> > On Mon, Aug 16, 2010 at 09:07:24PM +0400, pluknet wrote:
>> >> On 16 August 2010 21:05, pluknet <pluknet@gmail.com> wrote:
>> >> > Hi.
>> >> >
>> >> > Seeing on mostly idle, recently updated current, while closing a file.
>> >> > Presumably never reported on ML.
>> [...]
>> >>
>> > Both LORs are valid. The fork performed deep inside the VFS call stack
>> > is obviously problematic. As a workaround, you may fix the number of
>> > nfsiods.
>> >
>> > Proper fix might consist of creating a shepherd thread which only task
>> > is to act on the requests on creating new nfsiods.
>> >
>> > Would you try to implement this ? I will provide the assistance, if needed.
>>
>> Hmm.. I tried to move kproc_create() under shepherd thread and now stuck
>> with cp process lockup in [bo_wwait] when cp'ing something on nfs: cp a b.
>> Did I screw up something?
>> See weird draft patch attached (weird, as I have no idea how to nicely
>> exchange data between nfs_nfsiodnew() and shep_thread() thread).
> Most likely, you loose the requests to create nfsiods since the
> existing request in the global variable shep_chan can be overwritten
> by new request. You should either sleep till existing request is serviced,
> or form a queue.

It turns out I passed pointer to pointer instead of pointer
(sorry for my poor English).

>
> Also please take a note of the John' suggestion to use the taskqueue.

I decided to go this road. Thank you both.
Now I do nfs buildkernel survive and prepare some benchmark results.

-- 
wbr,
pluknet



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