linux-kernel - Re: Fwd: NFS , Kjournald - status D (uninterruptible sleep)

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Message-ID: <e9aeeef80712170841u6c908f0cg3b008b995ecd63f4@mail.gmail.com>
Date:	Mon, 17 Dec 2007 14:41:18 -0200
From:	Denis <denismpa@...il.com>
To:	"Jan Kara" <jack@...e.cz>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Fwd: NFS , Kjournald - status D (uninterruptible sleep) - maquina lenta.

2007/12/17, Jan Kara <jack@...e.cz>:
> > Dears, I've got a double dual xeon wich sometimes is getting too slow.
> >
> >
> > While i was observing one of these slowly times, I realized the time
> > wait of processors come close to 100% and nfsd and kjournald process
> > become to D status (uniterruptible sleep) .Does someone know why this
> > can be happening or how can I troubleshoot it?
> >
> > Below is a 'draw' of my top at one of these moments.
> >
> > [root@...mo src]# top
> > top - 10:59:02 up 6 days, 19:30, 17 users,  load average: 14.77, 13.46, 13.00
> > Tasks: 189 total,   1 running, 188 sleeping,   0 stopped,   0 zombie
> > Cpu0  :  0.0% us,  0.4% sy,  0.0% ni,  0.2% id, 98.5% wa,  0.0% hi,  0.9% si
> > Cpu1  :  0.0% us,  0.4% sy,  0.0% ni,  0.0% id, 99.6% wa,  0.0% hi,  0.0% si
> > Cpu2  :  0.0% us,  0.2% sy,  0.0% ni,  7.8% id, 92.0% wa,  0.0% hi,  0.0% si
> > Cpu3  :  0.2% us,  0.8% sy,  0.0% ni,  0.0% id, 98.7% wa,  0.2% hi,  0.0% si
>  All processors are in iowait - i.e. waiting for IO.
>
> > Mem:   4025540k total,  4018264k used,     7276k free,     7908k buffers
> > Swap:  4096564k total,     3288k used,  4093276k free,  3553252k cached
> >
> >  3941 root      15   0     0    0    0 D    2  0.0  80:29.30 nfsd
> >  3938 root      15   0     0    0    0 D    1  0.0  81:02.02 nfsd
> >  2459 root      15   0     0    0    0 D    1  0.0  30:57.04 kjournald
> >  3937 root      15   0     0    0    0 D    1  0.0  82:07.99 nfsd
> >    96 root      15   0     0    0    0 S    0  0.0  34:12.48 kswapd0
> >  3940 root      15   0     0    0    0 D    0  0.0  80:22.55 nfsd
> >  3942 root      15   0     0    0    0 D    0  0.0  80:23.66 nfsd
> >  3939 root      15   0     0    0    0 D    0  0.0  82:22.55 nfsd
>  It seems like heavy disk/network activity. You can try running
> vmstat 1
>  It will print every second the situation of your memory / IO
> subsystem. You should especially see the ---io--- column ('bi' means
> blocks in, 'bo' blocks outputted). I guess they'd contain some
> non-trivial values...

>
>                                                                Honza
> --
> Jan Kara <jack@...e.cz>
> SuSE CR Labs
>

Hello, Jan.

The output of my vmstat look like this:

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 0  1   3612 239600   2828 3364300    0    0  1494  1300   10     4  0  3 80 17
 0  1   3612 187756   2872 3413420    0    0    44 24608 4274 10679  0 12 72 17
 0  1   3612 153196   2900 3446100    0    0    28 17248 3349  6018  0  7 72 20
 0  4   3612 134804   2908 3453980    0    0     8 61140 1795  4528  0  3 31 65
 1  0   3612 144592   2920 3458796    0    0     4 18972 1689  2102  0  2 37 62
 0  2   3612  86936   2980 3512048    0    0    56 26656 4554 14563  0 13 69 18
 0  2   3612  45424   3024 3552532    0    0    40 19076 3774  8148  0  9 71 20
 0  1   3612  15792   3048 3579368    0    0    44 25696 4430 11954  0 12 72 16
 0  4   3612   7892   3064 3576972    0    0    16 74808 2430 12205  0  6 57 37
 0  1   3612  17828   3080 3581512    0    0     8 18832 2423  6117  0  5 50 45
 1  0   3612  16944   3068 3581048    0    0    40 26816 4126 15803  0 12 66 22
 0  0   3612  16032   3128 3578200    0    0    60 32640 5137 23987  0 15 68 17
 1  0   3612  15664   3144 3576620    0    0    56 33200 5178 17395  0 15 71 14
 0  5   3612   7956   3160 3573272    0    0    20 74092 2077  5504  0  4 54 41
 0  6   3612  12212   3168 3578568    0    0     8 30936 1964  3848  0  3 42 55
 1  1   3612  15752   3200 3579760    0    0    24 22352 2975  9692  0  8 60 32
 0  1   3612  16696   3240 3577340    0    0    40 22496 3954 15224  0 12 71 17
 2  0   3612  15472   3212 3576824    0    0    40 26624 4466 14382  0 13 71 16
 1  3   3612   5908   3228 3575924    0    0    16 72304 2328  8965  0  5 39 55
 0  1   3612  14188   3244 3579512    0    0     8 17892 2169  4147  0  4 57 39
 0  2   3612  17136   3292 3575520    0    0    56 28100 4672 16158  0 15 69 16


So, the bo, appears to be the problem.

>  BTW: I guess the processes wake up eventually, don't they?
Yes, they eventually wake up for a while and then get in
initerruptible sleep again

Considering that the BO is the problem, what can I try to fix it?

Thanks,
-- 
Denis Anjos.
Cisco Certified Network Associate.
Universidade Federal do ABC
Santo André - SP - BR
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