2007/12/17, Jan Kara <[email protected]>:
> > 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@cromo 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 <[email protected]>
> 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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