Hi all,
we got a report about a system where fhgfs has a rather high latency
(fhgfs is running on top of xfs) and while investigating the system I
noticed that the system was rather cpu bound.
I'm not sure, but somehow CPU usage went down after disabling swap.
Is the lock contention a known issue?
kernel version: 3.8.2
spin_lock
# Overhead Command Shared Object Symbol
# ........ ............... ............................................................................................. ..............................................................................................................................
#
63.93% fhgfs-storage/M [kernel.kallsyms] 0xffffffff815d31bd k [k] _raw_spin_lock_irq
|
--- _raw_spin_lock_irq
|
|--99.44%-- shrink_inactive_list
| shrink_lruvec
| shrink_zone
| shrink_zones
| do_try_to_free_pages
| try_to_free_pages
| __alloc_pages_slowpath
| __alloc_pages_nodemask
| |
| |--99.98%-- alloc_pages_current
| | |
| | |--100.00%-- __page_cache_alloc
| | | |
| | | |--100.00%-- grab_cache_page_write_begin
| | | | xfs_vm_write_begin
| | | | generic_perform_write
| | | | generic_file_buffered_write
| | | | xfs_file_buffered_aio_write
| | | | xfs_file_aio_write
| | | | do_sync_write
| | | | vfs_write
| | | | sys_write
| | | | system_call_fastpath
| | | | 0x2aaaaba8f4ed
| | | --0.00%-- [...]
| | --0.00%-- [...]
| --0.02%-- [...]
--0.56%-- [...]
3.73% fhgfs-storage/M [kernel.kallsyms] 0xffffffff815d3533 k [k] _raw_spin_lock_irqsave
|
--- _raw_spin_lock_irqsave
|
|--97.82%-- pagevec_lru_move_fn
| |
| |--91.28%-- __pagevec_lru_add
| | |
| | |--86.17%-- __lru_cache_add
| | | add_to_page_cache_lru
| | | grab_cache_page_write_begin
| | | xfs_vm_write_begin
| | | generic_perform_write
| | | generic_file_buffered_write
| | | xfs_file_buffered_aio_write
| | | xfs_file_aio_write
| | | do_sync_write
| | | vfs_write
Thanks,
Bernd
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