swap_pager forgetting device?
Wolfgang Zenker
wolfgang at lyxys.ka.sub.org
Mon Feb 20 05:28:21 PST 2006
Hello,
I have a strange effect on a heavily used webserver (Apache 1.3 & PHP5)
running 5.4-RELEASE-p11.
This machine did use a lot of its 16 GB of swap last Friday, but recovered
since then with now 46 MB of swap being used:
# swapinfo
Device 1K-blocks Used Avail Capacity
/dev/da0s1b 16777216 46652 16730564 0%
Now I see messages like these in syslog:
Feb 20 12:20:03 www1 kernel: swap_pager: indefinite wait buffer: device: [NULL], blkno: 94333, size: 8192
Feb 20 12:20:03 www1 kernel: swap_pager: indefinite wait buffer: device: [NULL], blkno: 42814, size: 32768
I guess they are related to these processes:
# ps axuw | grep 'D.*httpd'
www 4130 0.0 0.5 36996 19248 ?? DL Fri07PM 0:13.02 /usr/local/sbin/httpd -DSSL
www 4140 0.0 0.0 7944 8 ?? DE Fri07PM 0:06.86 /usr/local/sbin/httpd -DSSL
www 4182 0.0 0.3 35696 9220 ?? DL Fri07PM 0:07.85 /usr/local/sbin/httpd -DSSL
www 4184 0.0 0.2 35808 8424 ?? DL Fri07PM 0:09.89 /usr/local/sbin/httpd -DSSL
Looks to me like the swap_pager swapped out blocks used by these processes
and somehow managed to "forget" the device.
Anyone seen this before?
Wolfgang
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