Messages in this thread | | | Date | Mon, 25 Jan 2010 14:22:39 +0100 (CET) | From | Jan Engelhardt <> | Subject | Re: kswapd continuously active |
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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 >> [000000000079299c] __wait_on_bit+0x58/0xb8 >> [0000000000792a5c] out_of_line_wait_on_bit+0x60/0x74 >> [000000000053ca3c] bdi_sync_writeback+0x6c/0x7c >> [000000000053ca78] sync_inodes_sb+0x10/0xfc >> [0000000000540dd0] __sync_filesystem+0x50/0x88 >> [0000000000540ec8] sync_filesystems+0xc0/0x124 >> [0000000000540f80] sys_sync+0x1c/0x48 >> [0000000000406294] linux_sparc_syscall+0x34/0x44 >> >> kswapd is also active all the time, writing something to disk - LED is >> blinking, and that's been going on for over half an hour despite the box >> being not busy. How do I see what kswapd is still flushing to disk? Even >> if all RAM (8 GB) was filled with dirty data, syncing it out would not >> take that long - that is to say, the sync process should have long >> exited. > >That doesn't sound good. What does /proc/meminfo say? What file systems >are you using?
Eventually that day, the sync finished; not sure what triggered that. Usually, meminfo looks like when the box is doing something:
14:08 ares:~ > cat /proc/meminfo MemTotal: 8166752 kB MemFree: 3243552 kB Buffers: 207968 kB Cached: 2728216 kB SwapCached: 0 kB Active: 2203136 kB Inactive: 2152544 kB Active(anon): 1167256 kB Inactive(anon): 252952 kB Active(file): 1035880 kB Inactive(file): 1899592 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 141624 kB Writeback: 0 kB AnonPages: 1421448 kB Mapped: 49904 kB Shmem: 680 kB Slab: 429784 kB SReclaimable: 315760 kB SUnreclaim: 114024 kB KernelStack: 9248 kB PageTables: 6120 kB Quicklists: 10560 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 4083376 kB Committed_AS: 1626280 kB VmallocTotal: 1069547520 kB VmallocUsed: 28816 kB VmallocChunk: 1069518664 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 4096 kB 14:16 ares:~ > w 14:17:13 up 6:26, 2 users, load average: 21.09, 24.41, 22.49
This is used as a compile box, and there are lots of files created and deleted when there is work - a new chroot for every package basically, with a total of about 300K such "floating" files. Filesystem is ext4.
/dev/sda4 / ext4 rw,relatime,barrier=1,data=ordered 0 0
Now that I see barrier=1, maybe I should turn that off in the future like I did with XFS around 2.6.17[1].
[1] http://lkml.indiana.edu/hypermail/linux/kernel/0605.2/1110.html
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