Hi, Am 14.10.2016 um 15:19 schrieb Stefan Priebe - Profihost AG: > Dear julian, > > Am 14.10.2016 um 14:26 schrieb Julian Taylor: >> On 10/14/2016 08:28 AM, Stefan Priebe - Profihost AG wrote: >>> Hello list, >>> >>> while running the same workload on two machines (single xeon and a dual >>> xeon) both with 64GB RAM. >>> >>> I need to run echo 3 >/proc/sys/vm/drop_caches every 15-30 minutes to >>> keep the speed as good as on the non numa system. I'm not sure whether >>> this is related to numa. >>> >>> Is there any sysctl parameter to tune? >>> >>> Tested with vanilla v4.8.1 >>> >>> Greets, >>> Stefan >> >> hi, >> why do you think this is related to btrfs? > > was just an idea as i couldn't find any other difference between those > systems. > >> This is easy to diagnose but recording some kernel stacks during the > > problem with perf. > > you just mean perf top? Does it also show locking problems? As i see not > much CPU usage in that case.
perf top looks like this: 5,46% libc-2.19.so [.] memset 5,26% [kernel] [k] page_fault 3,63% [kernel] [k] clear_page_c_e 1,38% [kernel] [k] _raw_spin_lock 1,06% [kernel] [k] get_page_from_freelist 0,83% [kernel] [k] copy_user_enhanced_fast_string 0,79% [kernel] [k] release_pages 0,68% [kernel] [k] handle_mm_fault 0,57% [kernel] [k] free_hot_cold_page 0,55% [kernel] [k] handle_pte_fault 0,54% [kernel] [k] __pagevec_lru_add_fn 0,45% [kernel] [k] unmap_page_range 0,45% [kernel] [k] __mod_zone_page_state 0,43% [kernel] [k] page_add_new_anon_rmap 0,38% [kernel] [k] free_pcppages_bulk > >> The only known issue that has this type of workaround that I know of are >> transparent huge pages. > > I already disabled thp by: > echo never > /sys/kernel/mm/transparent_hugepage/enabled > > cat /proc/meminfo says: > HugePages_Total: 0 > HugePages_Free: 0 > HugePages_Rsvd: 0 > HugePages_Surp: 0 > > > > Greets, > Stefan > >> >> cheers, >> Julian -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
