Hi. I have a 3.13 (ubuntu LTS) server with 3TB of memory and under certain load conditions it can spiral off to 80+% system load. Per recommendation on IRC yesterday I have captured 2 perf reports (I'm new to perf, so I'm not sure they tell precisely whats needed. Bad situation (high sysload 80%+) Samples: 381K of event 'cycles', Event count (approx.): 1228296411165 + 27.84% postgres [kernel.kallsyms] [k] isolate_freepages_block + 21.08% psql [kernel.kallsyms] [k] isolate_freepages_block + 20.72% pg_restore [kernel.kallsyms] [k] isolate_freepages_block + 3.94% postgres postgres [.] pglz_compress + 2.86% postgres [kernel.kallsyms] [k] set_pageblock_flags_mask + 2.35% bacula-fd [kernel.kallsyms] [k] isolate_freepages_block + 2.07% pg_restore [kernel.kallsyms] [k] set_pageblock_flags_mask + 2.06% psql [kernel.kallsyms] [k] set_pageblock_flags_mask + 1.56% postgres libc-2.15.so [.] 0x000000000003c95f + 0.93% irqbalance [kernel.kallsyms] [k] isolate_freepages_block + 0.88% pg_restore [kernel.kallsyms] [k] isolate_freepages + 0.87% psql [kernel.kallsyms] [k] isolate_freepages + 0.86% postgres [kernel.kallsyms] [k] isolate_freepages + 0.81% postgres postgres [.] 0x000000000027ff5b + 0.60% postgres [kernel.kallsyms] [k] get_pageblock_flags_mask + 0.44% proc_pri [kernel.kallsyms] [k] isolate_freepages_block Good situation .. sysload < 5% Samples: 509K of event 'cycles', Event count (approx.): 1635259826919 + 21.14% postgres postgres [.] pglz_compress + 14.46% postgres postgres [.] 0x000000000016b643 + 10.11% postgres libc-2.15.so [.] 0x0000000000092f69 + 5.74% postgres postgres [.] s_lock + 2.86% postgres postgres [.] LWLockAcquire + 2.51% pg_restore [kernel.kallsyms] [k] isolate_freepages_block + 2.33% postgres postgres [.] NextCopyFromRawFields + 2.15% postgres postgres [.] LWLockRelease + 2.10% postgres postgres [.] _start + 1.93% postgres [kernel.kallsyms] [k] copy_user_enhanced_fast_string + 1.70% postgres [kernel.kallsyms] [k] change_pte_range + 1.61% postgres postgres [.] pg_verify_mbstr_len + 1.31% postgres postgres [.] hash_search_with_hash_value + 1.21% postgres libc-2.15.so [.] __strcoll_l + 0.86% kswapd0 [kernel.kallsyms] [k] __mem_cgroup_uncharge_common + 0.72% postgres postgres [.] heap_fill_tuple + 0.68% bacula-fd [kernel.kallsyms] [k] isolate_freepages_block + 0.66% postgres [kernel.kallsyms] [k] clear_page_c_e + 0.63% pg_restore [kernel.kallsyms] [k] copy_user_enhanced_fast_string Hugepages are disabled. All suggestions for configuration changes, etc are welcome? IO subsystem is not particulary busy in any of the situations. A sar output can be seen here: http://thread.gmane.org/gmane.linux.kernel/1908263 Jesper -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>