Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753979AbbFOFnN (ORCPT ); Mon, 15 Jun 2015 01:43:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41670 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751386AbbFOFnM (ORCPT ); Mon, 15 Jun 2015 01:43:12 -0400 Message-ID: <557E65E7.9010000@redhat.com> Date: Mon, 15 Jun 2015 01:43:03 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Leon Romanovsky , Ebru Akagunduz CC: Linux-MM , Andrew Morton , kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange , 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 Subject: Re: [RFC 2/3] mm: make optimistic check for swapin readahead References: <1434294283-8699-1-git-send-email-ebru.akagunduz@gmail.com> <1434294283-8699-3-git-send-email-ebru.akagunduz@gmail.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1804 Lines: 44 On 06/15/2015 01:40 AM, Leon Romanovsky wrote: > 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 >> @@ -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. I believe that Ebru's main focus for this initial version of the patch series was to get the _mechanism_ (patch 3) right, while having a fairly simple policy to drive it. Any suggestions on when it is a good idea to bring in pages from swap, and whether to treat resident-in-swap-cache pages differently from need-to-be-paged-in pages, and what other factors should be examined, are very welcome... -- All rights reversed -- 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/