Andi Kleen wrote:
Hmm.. The system hanging up for 5 minutes
I've actually seen that before on different systems. Sometimes
under some IO loads writes can be really starved for that long
and they block the calling process. Normally it only happened
when a very slow IO device (like slow USB storage) was involved
e.g. typical trace:
sshd D ffff810001072b20 0 11554 3381 11556 11127 (NOTLB)
ffff810114dffb08 0000000000000086 5353535353535353 5353535353535353
5353535353535353 000000000000057e ffff81014b344af0 ffff81014b404770
000001ede41c7140 ffff81014b344cc8 5353535300000001 5353535353535353
Call Trace:
[<ffffffff802e8cc2>] start_this_handle+0x2f4/0x37b
[<ffffffff802e8e16>] journal_start+0xcd/0x105
[<ffff81014b11e800>]
DWARF2 unwinder stuck at 0xffff81014b11e800
Leftover inexact backtrace:
[<ffffffff802da5f5>] ext3_dirty_inode+0x28/0x7b
[<ffffffff80291bbb>] __mark_inode_dirty+0x2c/0x17d
[<ffffffff80256611>] do_generic_mapping_read+0x3b0/0x3c2
[<ffffffff80255415>] file_read_actor+0x0/0xd6
[<ffffffff80256d8b>] generic_file_aio_read+0x164/0x1b8
[<ffffffff80278774>] do_sync_read+0xc9/0x10c
[<ffffffff80241ecc>] autoremove_wake_function+0x0/0x2e
[<ffffffff80531aef>] cond_resched+0x34/0x3b
[<ffffffff80258f27>] __alloc_pages+0x5e/0x2ae
[<ffffffff8027365a>] cache_alloc_refill+0xf1/0x1f8
[<ffffffff80278ade>] vfs_read+0xa8/0x14e
[<ffffffff8027bbbd>] kernel_read+0x38/0x4c
[<ffffffff8027d6d4>] do_execve+0x105/0x1f9
[<ffffffff80207bc9>] sys_execve+0x33/0x8b
[<ffffffff80209857>] stub_execve+0x67/0xb0
I've got quite a lot of processes in journal_start -> start_this_handle.
I suppose they're waiting for the transaction to finish.
It could be that with 8GB of RAM you've got a ton of buffered writes
piled up which the kernel has decided need to be written out and which
takes 5 minutes.. That amount of time seems a bit extreme to be blocking
other IO, though..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page: http://www.roberthancock.com/
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