On Tuesday 20 November 2007 06:55:52 Mark Hahn wrote:
> > I know this is a high end configuration, but no latency critical
> > component is at any limit, 4 CPUs are idling, PCI-X busses are
> > far away from being saturated.
>
> yes, but what about memory? I speculate that this is an Intel-based
> system that is relatively memory-starved.
Yes, its an intel system, since still has problems to deliver AMD quadcores.
Anyway, I don't believe the systems memory bandwidth is only
6 x 280 MB/s = 1680 MB/s (280 MB/s is the maximum I measured per scsi
channel). Actually, the measured bandwith of this system is 4 GB/s.
With 2.6.23 and enabled debugging we now nicely get softlockups.
[ 187.913000] Call Trace:
[ 187.917128] [<ffffffff8020d3c1>] show_trace+0x41/0x70
[ 187.922401] [<ffffffff8020d400>] dump_stack+0x10/0x20
[ 187.927667] [<ffffffff80269949>] softlockup_tick+0x129/0x180
[ 187.933529] [<ffffffff80240c9d>] update_process_times+0x7d/0xa0
[ 187.939676] [<ffffffff8021c634>] smp_local_timer_interrupt+0x34/0x60
[ 187.946275] [<ffffffff8021c71a>] smp_apic_timer_interrupt+0x4a/0x70
[ 187.952731] [<ffffffff8020c7db>] apic_timer_interrupt+0x6b/0x70
[ 187.958848] [<ffffffff881ca5e3>] :raid456:handle_stripe+0xe23/0xf50
[ 187.965360] [<ffffffff881cb365>] :raid456:raid5d+0x2d5/0x3e0
[ 187.971267] [<ffffffff881a0ff9>] :md_mod:md_thread+0x39/0x130
[ 187.977246] [<ffffffff8024c73c>] kthread+0x6c/0xa0
[ 187.982225] [<ffffffff8020c9b8>] child_rip+0xa/0x12
[ 187.988910]
[ 207.232587] BUG: soft lockup detected on CPU#1!
[ 207.237405]
[ 207.237405] Call Trace:
[ 207.241672] [<ffffffff8020d3c1>] show_trace+0x41/0x70
[ 207.247049] [<ffffffff8020d400>] dump_stack+0x10/0x20
[ 207.252470] [<ffffffff80269949>] softlockup_tick+0x129/0x180
[ 207.258513] [<ffffffff80240c9d>] update_process_times+0x7d/0xa0
[ 207.264651] [<ffffffff8021c634>] smp_local_timer_interrupt+0x34/0x60
[ 207.271222] [<ffffffff8021c71a>] smp_apic_timer_interrupt+0x4a/0x70
[ 207.277698] [<ffffffff8020c7db>] apic_timer_interrupt+0x6b/0x70
[ 207.283819] [<ffffffff8023c6c9>] __do_softirq+0x59/0x100
[ 207.289332] [<ffffffff8020cd2c>] call_softirq+0x1c/0x30
[ 207.294743] [<ffffffff8020f165>] do_softirq+0x75/0xe0
[ 207.299998] [<ffffffff8020ee72>] do_IRQ+0xc2/0x1b0
[ 207.305010] [<ffffffff8020c076>] ret_from_intr+0x0/0xf
[ 207.310346] [<ffffffff80515606>] _spin_unlock_irq+0x26/0x30
[ 207.316111] [<ffff8101234d97a8>]
[ 207.319509] DWARF2 unwinder stuck at 0xffff8101234d97a8
[ 207.324905] Leftover inexact backtrace:
[ 207.328843] [<ffffffff80515565>] _spin_unlock_irqrestore+0x55/0x70
[ 207.335236] [<ffffffff8025517d>] trace_hardirqs_on+0xbd/0x160
[ 207.341184] [<ffffffff881a0ff9>] :md_mod:md_thread+0x39/0x130
[ 207.347123] [<ffffffff8024cdf0>] autoremove_wake_function+0x0/0x30
[ 207.353504] [<ffffffff8024cdf0>] autoremove_wake_function+0x0/0x30
[ 207.359898] [<ffffffff881a0fc0>] :md_mod:md_thread+0x0/0x130
[ 207.365761] [<ffffffff8024c73c>] kthread+0x6c/0xa0
[ 207.370765] [<ffffffff8020c9b8>] child_rip+0xa/0x12
[ 207.375855] [<ffffffff8020c0cc>] restore_args+0x0/0x30
[ 207.381172] [<ffffffff8024c6d0>] kthread+0x0/0xa0
[ 207.386089] [<ffffffff8020c9ae>] child_rip+0x0/0x12
[ 207.391169]
[ 219.044383] BUG: soft lockup detected on CPU#1!
(gdb) l *(handle_stripe+0xe23)
0x5613 is in handle_stripe (drivers/md/raid5.c:1853).
1848
1849 static void end_reshape(raid5_conf_t *conf);
1850
1851 static int page_is_zero(struct page *p)
1852 {
1853 char *a = page_address(p);
1854 return ((*(u32*)a) == 0 &&
1855 memcmp(a, a+4, STRIPE_SIZE-4)==0);
1856 }
1857
Any ideas how to debug this?
Thanks,
Bernd
--
Bernd Schubert
Q-Leap Networks GmbH
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