LOR on nfs: vfs_vnops.c:301 kern_descrip.c:1580

[pluknet]

On 18 August 2010 17:46, Kostik Belousov <kostikbel at gmail.com> wrote:
> On Wed, Aug 18, 2010 at 02:43:19PM +0400, pluknet wrote:
>> On 18 August 2010 12:07, pluknet <pluknet at gmail.com> wrote:
>> > On 17 August 2010 20:04, Kostik Belousov <kostikbel at gmail.com> wrote:
>> >
>> >>
>> >> 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.
>> >
>>
>> So, I modified the patch to defer proc_create() with taskqueue(9).
>> Below is `time make -j5 buildkernel WITHOUT_MODULES=yes` perf. evaluation.
>> Done on 4-way CPU on clean /usr/obj with /usr/src & /usr/obj both
>> nfs-mounted over 1Gbit LAN.
>>
>> clean old
>> 1137.985u 239.411s 7:42.15 298.0%       6538+2133k 87+43388io 226pf+0w
>>
>> clean new
>> 1134.755u 240.032s 7:41.25 298.0%       6553+2133k 87+43367io 224pf+0w
>>
>> Patch needs polishing, though it generally works.
>> Not sure if shep_chan (or whatever name it will get) needs locking.
> As I said yesterday, if several requests to create nfsiod coming one
> after another, you would loose all but the last.
>
> You should put the requests into the list, probably protected by
> nfs_iod_mtx.
>

How about this patch? Still several things to ask.
1) I used malloc instance w/ M_NOWAIT, since it's called with nfs_iod_mtx held.
2) Probably busy/done gymnastics is a wrong mess. Your help is appreciated.
3) if (1) is fine, is it right to use fail: logic (i.e. set
NFSIOD_NOT_AVAILABLE)
on memory shortage? Not tested.

There are debug printf() left intentionally to see how 3 contexts run under load
to each other. I attached these messages as well if that makes sense.

-- 
wbr,
pluknet
-------------- next part --------------
A non-text attachment was scrubbed...
Name: dmesg.out
Type: application/octet-stream
Size: 5158 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-current/attachments/20100818/efbe27f0/dmesg.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: nfsiod_tq_lock.diff
Type: text/x-patch
Size: 4542 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-current/attachments/20100818/efbe27f0/nfsiod_tq_lock.bin