Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753958AbbFOFke (ORCPT ); Mon, 15 Jun 2015 01:40:34 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:33821 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751386AbbFOFkZ (ORCPT ); Mon, 15 Jun 2015 01:40:25 -0400 MIME-Version: 1.0 X-Originating-IP: [212.25.79.130] In-Reply-To: <1434294283-8699-3-git-send-email-ebru.akagunduz@gmail.com> References: <1434294283-8699-1-git-send-email-ebru.akagunduz@gmail.com> <1434294283-8699-3-git-send-email-ebru.akagunduz@gmail.com> From: Leon Romanovsky Date: Mon, 15 Jun 2015 08:40:03 +0300 Message-ID: Subject: Re: [RFC 2/3] mm: make optimistic check for swapin readahead To: Ebru Akagunduz Cc: Linux-MM , Andrew Morton , kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange , riel@redhat.com, iamjoonsoo.kim@lge.com, Xiexiuqi , gorcunov@openvz.org, "linux-kernel@vger.kernel.org" , Mel Gorman , rientjes@google.com, Vlastimil Babka , aneesh.kumar@linux.vnet.ibm.com, hughd@google.com, Johannes Weiner , mhocko@suse.cz, boaz@plexistor.com, raindel@mellanox.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5288 Lines: 131 On Sun, Jun 14, 2015 at 6:04 PM, Ebru Akagunduz wrote: > This patch makes optimistic check for swapin readahead > to increase thp collapse rate. Before getting swapped > out pages to memory, checks them and allows up to a > certain number. It also prints out using tracepoints > amount of unmapped ptes. > > Signed-off-by: Ebru Akagunduz > --- > include/trace/events/huge_memory.h | 11 +++++++---- > mm/huge_memory.c | 13 ++++++++++--- > 2 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h > index 4b9049b..53c9f2e 100644 > --- a/include/trace/events/huge_memory.h > +++ b/include/trace/events/huge_memory.h > @@ -9,9 +9,9 @@ > TRACE_EVENT(mm_khugepaged_scan_pmd, > > TP_PROTO(struct mm_struct *mm, unsigned long vm_start, bool writable, > - bool referenced, int none_or_zero, int collapse), > + bool referenced, int none_or_zero, int collapse, int unmapped), > > - TP_ARGS(mm, vm_start, writable, referenced, none_or_zero, collapse), > + TP_ARGS(mm, vm_start, writable, referenced, none_or_zero, collapse, unmapped), > > TP_STRUCT__entry( > __field(struct mm_struct *, mm) > @@ -20,6 +20,7 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, > __field(bool, referenced) > __field(int, none_or_zero) > __field(int, collapse) > + __field(int, unmapped) > ), > > TP_fast_assign( > @@ -29,15 +30,17 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, > __entry->referenced = referenced; > __entry->none_or_zero = none_or_zero; > __entry->collapse = collapse; > + __entry->unmapped = unmapped; > ), > > - TP_printk("mm=%p, vm_start=%04lx, writable=%d, referenced=%d, none_or_zero=%d, collapse=%d", > + TP_printk("mm=%p, vm_start=%04lx, writable=%d, referenced=%d, none_or_zero=%d, collapse=%d, unmapped=%d", > __entry->mm, > __entry->vm_start, > __entry->writable, > __entry->referenced, > __entry->none_or_zero, > - __entry->collapse) > + __entry->collapse, > + __entry->unmapped) > ); > > TRACE_EVENT(mm_collapse_huge_page, > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 9bb97fc..22bc0bf 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -24,6 +24,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -2639,11 +2640,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, > { > pmd_t *pmd; > pte_t *pte, *_pte; > - int ret = 0, none_or_zero = 0; > + int ret = 0, none_or_zero = 0, unmapped = 0; > struct page *page; > unsigned long _address; > spinlock_t *ptl; > - int node = NUMA_NO_NODE; > + int node = NUMA_NO_NODE, max_ptes_swap = HPAGE_PMD_NR/8; Sorry for asking, my knoweldge of THP is very limited, but why did you choose this default value? >From the discussion followed by your patch (https://lkml.org/lkml/2015/2/27/432), I got an impression that it is not necessary right value. > bool writable = false, referenced = false; > > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > @@ -2657,6 +2658,12 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, > for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; > _pte++, _address += PAGE_SIZE) { > pte_t pteval = *_pte; > + if (is_swap_pte(pteval)) { > + if (++unmapped <= max_ptes_swap) > + continue; > + else > + goto out_unmap; > + } > if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { > if (!userfaultfd_armed(vma) && > ++none_or_zero <= khugepaged_max_ptes_none) > @@ -2701,7 +2708,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, > out_unmap: > pte_unmap_unlock(pte, ptl); > trace_mm_khugepaged_scan_pmd(mm, vma->vm_start, writable, referenced, > - none_or_zero, ret); > + none_or_zero, ret, unmapped); > if (ret) { > node = khugepaged_find_target_node(); > /* collapse_huge_page will return with the mmap_sem released */ > -- > 1.9.1 > > -- > 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 -- Leon Romanovsky | Independent Linux Consultant www.leon.nu | leon@leon.nu -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/