From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx185.postini.com [74.125.245.185]) by kanga.kvack.org (Postfix) with SMTP id 3246F6B0031 for ; Thu, 5 Sep 2013 03:27:19 -0400 (EDT) Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 5 Sep 2013 12:46:34 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 98C751258053 for ; Thu, 5 Sep 2013 12:57:09 +0530 (IST) Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r857R9EM46465132 for ; Thu, 5 Sep 2013 12:57:10 +0530 Received: from d28av05.in.ibm.com (localhost [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r857RApT013644 for ; Thu, 5 Sep 2013 12:57:10 +0530 Date: Thu, 5 Sep 2013 15:27:08 +0800 From: Wanpeng Li Subject: Re: [PATCH] mm/thp: fix comments in transparent_hugepage_flags Message-ID: <20130905072708.GA15294@hacker.(null)> Reply-To: Wanpeng Li References: <1378301422-9468-1-git-send-email-wujianguo@huawei.com> <5227e870.ab42320a.62d4.3d12SMTPIN_ADDED_BROKEN@mx.google.com> <5227F4B6.40009@huawei.com> <20130905033704.GA18909@hacker.(null)> <52280058.5070803@huawei.com> <52280f92.e72b320a.2501.6de1SMTPIN_ADDED_BROKEN@mx.google.com> <522825E4.7080404@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <522825E4.7080404@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jianguo Wu Cc: Jianguo Wu , akpm@linux-foundation.org, aarcange@redhat.com, kirill.shutemov@linux.intel.com, mgorman@suse.de, xiaoguangrong@linux.vnet.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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 >>>>>>> --- >>>>>>> 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 herei 1/4 ? > >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@kvack.org. For more info on Linux MM, >>>>>>> see: http://www.linux-mm.org/ . >>>>>>> Don't email: email@kvack.org >>>>>> >>>>>> -- >>>>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in >>>>>> the body to majordomo@kvack.org. For more info on Linux MM, >>>>>> see: http://www.linux-mm.org/ . >>>>>> Don't email: email@kvack.org >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>>> . >>>> >>> >>> >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org >> >> > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org