Hello Linux Experts, Good morning/Good day !
Please look the attached Screen shot of Top output taken from a DB server. You would noticed 2 Uninterruptible process (in state 'D') in it. PIDs 9900 & 11240. In this server, we often experienced performance issue. When we investigate that time, we had noticed one or more processes in D state occupying hung chunk of Memory causing the high I/O wait on the server and the server would be running out of Physical Memory, which inturn would cause more Page swapping. Most of them we ended up rebooting the server to bring the server to Normal performance. Bcoz the 'kill -9' doesn't work with Uninterruptable process.
Now as a proactive measure, we are keeping close eye on this server. Today I found there are 2 Uninterruptable processes (in D state) shown on the top output. I waited for about an hour but the state isn't tend to changing to Sleep or Running. I have the liberty to kill any process on this server, so I tried 'kill -9', it didn't work. I checked the Memory segments occupied by this processes by running 'pmap -x' command.
Now my question is, Can I clear all the Memory segments that are associated with these processes in D state ? Please let me know. Thanks in advance !
[root@mlck-chi-pdb02 ~]# pmap -x 9900
9900: oraclePMLCKI1 (LOCAL=NO)
Address Kbytes RSS Anon Locked Mode Mapping
0000000000400000 99776 - - - r-x-- oracle
000000000666f000 532 - - - rw--- oracle
00000000066f4000 676 - - - rwx-- [ anon ]
0000000060000000 32768 - - - rw-s- [ shmid=0x38002 ]
0000000080000000 4177920 - - - rw-s- [ shmid=0x40003 ]
0000000180000000 4177920 - - - rw-s- [ shmid=0x48004 ]
0000000280000000 575488 - - - rw-s- [ shmid=0x50005 ]
0000002a95556000 8 - - - rw--- [ anon ]
0000002a95558000 4 - - - r-x-- libcwait.so
0000002a95559000 1020 - - - ----- libcwait.so
0000002a95658000 4 - - - rw--- libcwait.so
0000002a95659000 148 - - - r-x-- libskgxp10.so
0000002a9567e000 1024 - - - ----- libskgxp10.so
0000002a9577e000 8 - - - rw--- libskgxp10.so
0000002a95780000 940 - - - r-x-- libhasgen10.so
0000002a9586b000 1020 - - - ----- libhasgen10.so
0000002a9596a000 24 - - - rw--- libhasgen10.so
0000002a95970000 20 - - - rw--- [ anon ]
0000002a95975000 8 - - - r-x-- libskgxn2.so
0000002a95977000 1020 - - - ----- libskgxn2.so
0000002a95a76000 4 - - - rw--- libskgxn2.so