From: Michal Hocko <mhocko@kernel.org> To: "Odzioba, Lukasz" <lukasz.odzioba@intel.com> Cc: "Hansen, Dave" <dave.hansen@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "Shutemov, Kirill" <kirill.shutemov@intel.com>, "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> Subject: Re: mm: pages are not freed from lru_add_pvecs after process termination Date: Tue, 7 Jun 2016 13:19:46 +0200 [thread overview] Message-ID: <20160607111946.GJ12305@dhcp22.suse.cz> (raw) In-Reply-To: <D6EDEBF1F91015459DB866AC4EE162CC023F84C9@IRSMSX103.ger.corp.intel.com> On Tue 07-06-16 09:02:02, Odzioba, Lukasz wrote: [...] > //compile with: gcc bench.c -o bench_2M -fopenmp > //compile with: gcc -D SMALL_PAGES bench.c -o bench_4K -fopenmp > #include <stdio.h> > #include <sys/mman.h> > #include <omp.h> > > #define MAP_HUGE_SHIFT 26 > #define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT) > > #ifndef SMALL_PAGES > #define PAGE_SIZE (1024*1024*2) > #define MAP_PARAM (MAP_HUGE_2MB) Isn't MAP_HUGE_2MB ignored for !hugetlb pages? > #else > #define PAGE_SIZE (1024*4) > #define MAP_PARAM (0) > #endif > > void main() { > size_t size = ((60 * 1000 * 1000) / 288) * 1000; // 60GBs of memory 288 CPUs > #pragma omp parallel > { > unsigned int k; > for (k = 0; k < 10; k++) { > void *p = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_PARAM, -1, 0); I guess you want something like posix_memalign or start faulting in from an aligned address to guarantee you will fault 2MB pages. Also note that the default behavior for THP during the fault has changed recently (see 444eb2a449ef ("mm: thp: set THP defrag by default to madvise and add a stall-free defrag option") so you might need MADV_HUGEPAGE. Besides that I am really suspicious that this will be measurable at all. I would just go and spin a patch assuming you are still able to trigger OOM with the vanilla kernel. The bug fix is more important... -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: "Odzioba, Lukasz" <lukasz.odzioba@intel.com> Cc: "Hansen, Dave" <dave.hansen@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "Shutemov, Kirill" <kirill.shutemov@intel.com>, "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com> Subject: Re: mm: pages are not freed from lru_add_pvecs after process termination Date: Tue, 7 Jun 2016 13:19:46 +0200 [thread overview] Message-ID: <20160607111946.GJ12305@dhcp22.suse.cz> (raw) In-Reply-To: <D6EDEBF1F91015459DB866AC4EE162CC023F84C9@IRSMSX103.ger.corp.intel.com> On Tue 07-06-16 09:02:02, Odzioba, Lukasz wrote: [...] > //compile with: gcc bench.c -o bench_2M -fopenmp > //compile with: gcc -D SMALL_PAGES bench.c -o bench_4K -fopenmp > #include <stdio.h> > #include <sys/mman.h> > #include <omp.h> > > #define MAP_HUGE_SHIFT 26 > #define MAP_HUGE_2MB (21 << MAP_HUGE_SHIFT) > > #ifndef SMALL_PAGES > #define PAGE_SIZE (1024*1024*2) > #define MAP_PARAM (MAP_HUGE_2MB) Isn't MAP_HUGE_2MB ignored for !hugetlb pages? > #else > #define PAGE_SIZE (1024*4) > #define MAP_PARAM (0) > #endif > > void main() { > size_t size = ((60 * 1000 * 1000) / 288) * 1000; // 60GBs of memory 288 CPUs > #pragma omp parallel > { > unsigned int k; > for (k = 0; k < 10; k++) { > void *p = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_PARAM, -1, 0); I guess you want something like posix_memalign or start faulting in from an aligned address to guarantee you will fault 2MB pages. Also note that the default behavior for THP during the fault has changed recently (see 444eb2a449ef ("mm: thp: set THP defrag by default to madvise and add a stall-free defrag option") so you might need MADV_HUGEPAGE. Besides that I am really suspicious that this will be measurable at all. I would just go and spin a patch assuming you are still able to trigger OOM with the vanilla kernel. The bug fix is more important... -- Michal Hocko SUSE Labs -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-06-07 11:19 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-27 17:01 mm: pages are not freed from lru_add_pvecs after process termination Odzioba, Lukasz 2016-04-27 17:01 ` Odzioba, Lukasz 2016-04-27 17:11 ` Dave Hansen 2016-04-27 17:11 ` Dave Hansen 2016-04-28 14:37 ` Michal Hocko 2016-04-28 14:37 ` Michal Hocko 2016-05-02 13:00 ` Michal Hocko 2016-05-02 13:00 ` Michal Hocko 2016-05-04 19:41 ` Odzioba, Lukasz 2016-05-04 19:41 ` Odzioba, Lukasz 2016-05-04 20:16 ` Dave Hansen 2016-05-04 20:16 ` Dave Hansen 2016-05-04 20:36 ` Michal Hocko 2016-05-04 20:36 ` Michal Hocko 2016-05-05 7:21 ` Michal Hocko 2016-05-05 7:21 ` Michal Hocko 2016-05-05 17:25 ` Odzioba, Lukasz 2016-05-05 17:25 ` Odzioba, Lukasz 2016-05-11 7:38 ` Michal Hocko 2016-05-11 7:38 ` Michal Hocko 2016-05-06 15:10 ` Odzioba, Lukasz 2016-05-06 15:10 ` Odzioba, Lukasz 2016-05-06 16:04 ` Dave Hansen 2016-05-06 16:04 ` Dave Hansen 2016-05-11 7:53 ` Michal Hocko 2016-05-11 7:53 ` Michal Hocko 2016-05-13 11:29 ` Vlastimil Babka 2016-05-13 11:29 ` Vlastimil Babka 2016-05-13 12:05 ` Odzioba, Lukasz 2016-05-13 12:05 ` Odzioba, Lukasz 2016-06-07 9:02 ` Odzioba, Lukasz 2016-06-07 9:02 ` Odzioba, Lukasz 2016-06-07 11:19 ` Michal Hocko [this message] 2016-06-07 11:19 ` Michal Hocko 2016-06-08 8:51 ` Odzioba, Lukasz 2016-06-08 8:51 ` Odzioba, Lukasz 2016-05-02 14:39 ` Vlastimil Babka 2016-05-02 14:39 ` Vlastimil Babka 2016-05-02 15:01 ` Kirill A. Shutemov 2016-05-02 15:01 ` Kirill A. Shutemov 2016-05-02 15:13 ` Vlastimil Babka 2016-05-02 15:13 ` Vlastimil Babka 2016-05-02 15:49 ` Dave Hansen 2016-05-02 15:49 ` Dave Hansen 2016-05-02 16:02 ` Kirill A. Shutemov 2016-05-02 16:02 ` Kirill A. Shutemov 2016-05-03 7:37 ` Michal Hocko 2016-05-03 7:37 ` Michal Hocko 2016-05-03 10:07 ` Kirill A. Shutemov 2016-05-03 10:07 ` Kirill A. Shutemov
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