On Tue 19-05-15 16:13:02, Mel Gorman wrote: [...] > :ffffffff811c160f: je ffffffff811c1630 <mem_cgroup_try_charge+0x40> > :ffffffff811c1611: xor %eax,%eax > :ffffffff811c1613: xor %ebx,%ebx > 1 1.7e-05 :ffffffff811c1615: mov %rbx,(%r12) > 7 1.2e-04 :ffffffff811c1619: add $0x10,%rsp > 1211 0.0203 :ffffffff811c161d: pop %rbx > 5 8.4e-05 :ffffffff811c161e: pop %r12 > 5 8.4e-05 :ffffffff811c1620: pop %r13 > 1249 0.0210 :ffffffff811c1622: pop %r14 > 7 1.2e-04 :ffffffff811c1624: pop %rbp > 5 8.4e-05 :ffffffff811c1625: retq > :ffffffff811c1626: nopw %cs:0x0(%rax,%rax,1) > 295 0.0050 :ffffffff811c1630: mov (%rdi),%rax > 160703 2.6973 :ffffffff811c1633: mov %edx,%r13d Huh, what? Even if this was off by one and the preceding instruction has consumed the time. This would be reading from page->flags but the page should be hot by the time we got here, no? > #### MEL: I was surprised to see this atrocity. It's a PageSwapCache check > #### /usr/src/linux-4.0-vanilla/./arch/x86/include/asm/bitops.h:311 > #### /usr/src/linux-4.0-vanilla/include/linux/page-flags.h:261 > #### /usr/src/linux-4.0-vanilla/mm/memcontrol.c:5473 -- Michal Hocko SUSE Labs -- 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>