Hi Jianguo, On Thu, Sep 05, 2013 at 02:34:12PM +0800, Jianguo Wu wrote: >On 2013/9/5 12:58, Wanpeng Li wrote: > >> Hi Jianguo, >> On Thu, Sep 05, 2013 at 11:54:00AM +0800, Jianguo Wu wrote: >>> On 2013/9/5 11:37, Wanpeng Li wrote: >>> >>>> On Thu, Sep 05, 2013 at 11:04:22AM +0800, Jianguo Wu wrote: >>>>> Hi Wanpeng, >>>>> >>>>> On 2013/9/5 10:11, Wanpeng Li wrote: >>>>> >>>>>> Hi Jianguo, >>>>>> On Wed, Sep 04, 2013 at 09:30:22PM +0800, Jianguo Wu wrote: >>>>>>> Since commit d39d33c332(thp: enable direct defrag), defrag is enable >>>>>>> for all transparent hugepage page faults by default, not only in >>>>>>> MADV_HUGEPAGE regions. >>>>>>> >>>>>>> Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx> >>>>>>> --- >>>>>>> mm/huge_memory.c | 6 ++---- >>>>>>> 1 file changed, 2 insertions(+), 4 deletions(-) >>>>>>> >>>>>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>>>>>> index a92012a..abf047e 100644 >>>>>>> --- a/mm/huge_memory.c >>>>>>> +++ b/mm/huge_memory.c >>>>>>> @@ -28,10 +28,8 @@ >>>>>>> >>>>>>> /* >>>>>>> * By default transparent hugepage support is enabled for all mappings >>>>>> >>>>>> This is also stale. TRANSPARENT_HUGEPAGE_ALWAYS is not configured by default in >>>>>> order that avoid to risk increase the memory footprint of applications w/o a >>>>>> guaranteed benefit. >>>>>> >>>>> >>>>> Right, how about this: >>>>> >>>>> By default transparent hugepage support is disabled in order that avoid to risk >>>> >>>> I don't think it's disabled. TRANSPARENT_HUGEPAGE_MADVISE is configured >>>> by default. >>>> >>> >>> Hi Wanpeng, >>> >>> We have TRANSPARENT_HUGEPAGE and TRANSPARENT_HUGEPAGE_ALWAYS/TRANSPARENT_HUGEPAGE_MADVISE, >>> TRANSPARENT_HUGEPAGE_ALWAYS or TRANSPARENT_HUGEPAGE_MADVISE is configured only if TRANSPARENT_HUGEPAGE >>> is configured. >>> >>> By default, TRANSPARENT_HUGEPAGE=n, and TRANSPARENT_HUGEPAGE_ALWAYS is configured when TRANSPARENT_HUGEPAGE=y. >>> >>> commit 13ece886d9(thp: transparent hugepage config choice): >>> >>> config TRANSPARENT_HUGEPAGE >>> - bool "Transparent Hugepage Support" if EMBEDDED >>> + bool "Transparent Hugepage Support" >>> depends on X86 && MMU >>> - default y >>> >>> +choice >>> + prompt "Transparent Hugepage Support sysfs defaults" >>> + depends on TRANSPARENT_HUGEPAGE >>> + default TRANSPARENT_HUGEPAGE_ALWAYS >>> >> >> mmotm tree: >> >> grep 'TRANSPARENT_HUGEPAGE' .config >> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y >> CONFIG_TRANSPARENT_HUGEPAGE=y >> # CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS is not set >> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y >> >> distro: >> >> grep 'TRANSPARENT_HUGEPAGE' config-3.8.0-26-generic >> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y >> CONFIG_TRANSPARENT_HUGEPAGE=y >> # CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS is not set >> CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y >> > >Hi Wanpeng, > >I'm a little confused, at mm/Kconfig, TRANSPARENT_HUGEPAGE is not configured by default. > >and in x86_64, linus tree: > >$make defconfig >$grep 'TRANSPARENT_HUGEPAGE' .config >CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y ># CONFIG_TRANSPARENT_HUGEPAGE is not set > Ah, ok, maybe distro enable them. Regards, Wanpeng Li >Do i misunderstand something here？ > >Thanks > >> >>> Thanks, >>> Jianguo Wu >>> >>>> Regards, >>>> Wanpeng Li >>>> >>>>> increase the memory footprint of applications w/o a guaranteed benefit, and >>>>> khugepaged scans all mappings when transparent hugepage enabled. >>>>> Defrag is invoked by khugepaged hugepage allocations and by page faults for all >>>>> hugepage allocations. >>>>> >>>>> Thanks, >>>>> Jianguo Wu >>>>> >>>>>> Regards, >>>>>> Wanpeng Li >>>>>> >>>>>>> - * and khugepaged scans all mappings. Defrag is only invoked by >>>>>>> - * khugepaged hugepage allocations and by page faults inside >>>>>>> - * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived >>>>>>> - * allocations. >>>>>>> + * and khugepaged scans all mappings. Defrag is invoked by khugepaged >>>>>>> + * hugepage allocations and by page faults for all hugepage allocations. >>>>>>> */ >>>>>>> unsigned long transparent_hugepage_flags __read_mostly = >>>>>>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS >>>>>>> -- >>>>>>> 1.8.1.2 >>>>>>> >>>>>>> -- >>>>>>> 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> >>>>>> >>>>>> -- >>>>>> 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> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>>> . >>>> >>> >>> >> >> -- >> 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> >> >> > > -- 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>