From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751840AbbIQPNc (ORCPT ); Thu, 17 Sep 2015 11:13:32 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:38709 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751582AbbIQPNa (ORCPT ); Thu, 17 Sep 2015 11:13:30 -0400 Date: Thu, 17 Sep 2015 18:13:28 +0300 From: "Kirill A. Shutemov" To: Ebru Akagunduz Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, riel@redhat.com, iamjoonsoo.kim@lge.com, xiexiuqi@huawei.com, gorcunov@openvz.org, linux-kernel@vger.kernel.org, mgorman@suse.de, rientjes@google.com, vbabka@suse.cz, aneesh.kumar@linux.vnet.ibm.com, hughd@google.com, hannes@cmpxchg.org, mhocko@suse.cz, boaz@plexistor.com, raindel@mellanox.com Subject: Re: [RFC v5 3/3] mm: make swapin readahead to improve thp collapse rate Message-ID: <20150917151327.GA31549@node.dhcp.inet.fi> References: <1442259105-4420-1-git-send-email-ebru.akagunduz@gmail.com> <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1442259105-4420-4-git-send-email-ebru.akagunduz@gmail.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 14, 2015 at 10:31:45PM +0300, Ebru Akagunduz wrote: > This patch makes swapin readahead to improve thp collapse rate. > When khugepaged scanned pages, there can be a few of the pages > in swap area. > > With the patch THP can collapse 4kB pages into a THP when > there are up to max_ptes_swap swap ptes in a 2MB range. > > The patch was tested with a test program that allocates > 400B of memory, writes to it, and then sleeps. I force > the system to swap out all. Afterwards, the test program > touches the area by writing, it skips a page in each > 20 pages of the area. > > Without the patch, system did not swap in readahead. > THP rate was %65 of the program of the memory, it > did not change over time. > > With this patch, after 10 minutes of waiting khugepaged had > collapsed %99 of the program's memory. > > Signed-off-by: Ebru Akagunduz > Acked-by: Rik van Riel [ resend with correct TO/CC lists] >>From 9b28cf3159ff200d4a2543d73a06ae84d050aea2 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 17 Sep 2015 16:35:57 +0300 Subject: [PATCH] khugepaged: avoid usage of uninitialized variable 'isolated' MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In file included from include/trace/events/huge_memory.h:7:0, from mm/huge_memory.c:62: include/linux/tracepoint.h:141:5: warning: ‘isolated’ may be used uninitialized in this function [-Wmaybe-uninitialized] ((void(*)(proto))(it_func))(args); \ ^ mm/huge_memory.c:2327:6: note: ‘isolated’ was declared here int isolated, result = 0; We make use of isolated in error path before it get initialized. The patch also makes trivial cleanup of exit path of the function. Signed-off-by: Kirill A. Shutemov --- mm/huge_memory.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 5ad5c443cc94..857f92e85c38 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2656,8 +2656,6 @@ static void __collapse_huge_page_swapin(struct mm_struct *mm, trace_mm_collapse_huge_page_swapin(mm, swapped_in, 1); } - - static void collapse_huge_page(struct mm_struct *mm, unsigned long address, struct page **hpage, @@ -2669,7 +2667,7 @@ static void collapse_huge_page(struct mm_struct *mm, pgtable_t pgtable; struct page *new_page; spinlock_t *pmd_ptl, *pte_ptl; - int isolated, result = 0; + int isolated = 0, result = 0; unsigned long hstart, hend; struct mem_cgroup *memcg; unsigned long mmun_start; /* For mmu_notifiers */ @@ -2805,9 +2803,6 @@ static void collapse_huge_page(struct mm_struct *mm, result = SCAN_SUCCEED; out_up_write: up_write(&mm->mmap_sem); - trace_mm_collapse_huge_page(mm, isolated, result); - return; - out_nolock: trace_mm_collapse_huge_page(mm, isolated, result); return; -- Kirill A. Shutemov