Re: kswapd continuously active

[Jan Engelhardt]

On Monday 2010-01-25 14:22, Jan Engelhardt wrote:
>On Monday 2010-01-25 14:06, Jens Axboe wrote:
>>> 
>>> with 2.6.32.2 on sparc64 I am seeing that there is a sync(1) process 
>>> busy in D state, with the following trace:
>>> 
>>> sync          D 000000000079299c  7552  4851      1 0x208061101000004
>>> Call Trace:
>>>  [000000000053ca58] bdi_sched_wait+0xc/0x1c[...]
>>>  [000000000053ca78] sync_inodes_sb+0x10/0xfc
>>> 
>>> kswapd is also active all the time, writing something to disk[...]
>>
>>That doesn't sound good. What does /proc/meminfo say? What file systems
>>are you using?

>January 25			Feb-05
>MemTotal:        8166752 kB	8166752
>MemFree:         3243552 kB	3781776
>Buffers:          207968 kB	4912
>Cached:          2728216 kB	2684400
>SwapCached:            0 kB	0
>Active:          2203136 kB	495624
>Inactive:        2152544 kB	3263136
>Active(anon):    1167256 kB	488168
>Inactive(anon):   252952 kB	583912
>Active(file):    1035880 kB	7456
>Inactive(file):  1899592 kB	2679224
>Unevictable:           0 kB	0
>Mlocked:               0 kB	0
>SwapTotal:             0 kB	0
>SwapFree:              0 kB	0
>Dirty:            141624 kB	2662184
>Writeback:             0 kB	..

Today this happened again. So I looked at /proc/meminfo to paste today's
values next to those from January. That is when I noticed the "Dirty"
value - and thus I ran

	watch -d -n 1 'grep Dirty /proc/meminfo'

What I see is that the dirty amount - a sync is currently running -
only decreases with at most 400 KB/sec, often less than that.
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