11 Dec
2013
11 Dec
'13
10:32 p.m.
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> Von: sander.grendelman@gmail.com [sander.grendelman@gmail.com]" im A=
uftrag von "=0A=
> Gesendet: Mittwoch, 11. Dezember 2013 14:51=0A=
> An: Markus Stockhausen=0A=
> Cc: ovirt-users=0A=
> Betreff: Re: [Users] Abysmal network performance inside hypervisor node=
=0A=
> =0A=
> Then I'm also out of ideas.=0A=
> =0A=
> You could take al look at the options in /etc/vdsm/vdsm.conf=0A=
> ( information at /usr/share/doc/vdsm-*/vdsm.conf.sample )=0A=
=0A=
Ok, now it is getting crazy. Something is going on inside debugfs. =0A=
I do not know what activated it, but I have two candidates:=0A=
=0A=
1) DMA API debugging has been enabled. So I deactivated it with=0A=
echo Y > ./sys/kernel/debug/dma-api/disabled and instantly=0A=
throughput raises from 17MB/sec to 33MB/sec=0A=
=0A=
2) Another location I cannot identify up to know. A perf trace shows=0A=
the following consumption path.=0A=
=0A=
- 12,51% kworker/1:2 [kernel.kallsyms] [k] lock_is_held =
=0A=
- lock_is_held =0A=
- 82,25% __module_address =0A=
- 99,97% __module_text_address =0A=
is_module_text_address =0A=
__kernel_text_address =0A=
print_context_stack =0A=
dump_trace =0A=
save_stack_trace =0A=
- set_track =0A=
- 52,61% free_debug_processing =0A=
- __slab_free =0A=
- 93,67% kmem_cache_free =0A=
- 72,64% kfree_skbmem =0A=
- 91,34% __kfree_skb =0A=
- 92,58% napi_gro_receive =0A=
ipoib_ib_handle_rx_wc =0A=
ipoib_poll =0A=
net_rx_action =0A=
__do_softirq =0A=
call_softirq =0A=
- do_softirq =0A=
- 75,12% irq_exit =0A=
- 95,67% smp_apic_timer_interrupt =0A=
- apic_timer_interrupt =0A=
- 79,47% __slab_free =0A=
- 99,51% kmem_cache_free =0A=
- 99,19% nfs_free_request =0A=
nfs_release_request =0A=
nfs_readpage_release =0A=
nfs_read_completion =0A=
nfs_readdata_release =0A=
nfs_readpage_release_common =0A=
rpc_free_task =0A=
rpc_async_release =0A=
process_one_work =0A=
worker_thread =0A=
kthread =0A=
ret_from_fork =0A=
+ 0,81% nfs_readhdr_free =0A=
=0A=
Any idea what activates tracing for nfs kmem allocations?=0A=
=0A=
Markus=0A=
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