From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CC24ECAAD8 for ; Thu, 22 Sep 2022 01:16:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230325AbiIVBQb (ORCPT ); Wed, 21 Sep 2022 21:16:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230347AbiIVBQC (ORCPT ); Wed, 21 Sep 2022 21:16:02 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31EFFAB1B7 for ; Wed, 21 Sep 2022 18:15:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663809339; x=1695345339; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=7JGgeiKPZDSphe46TEdkWdM/ODuTtoo1WqFDi/uvOlw=; b=Lf14jrjkmm8HfzjYKRhJUdInsFk1MRU04TOE8YCAskNKsbNK4TolnylD aq9JZLSS5HjHoSHMNjz6JYJLaP7+wSj+p64I/hukgv5wwvg54vW/KDoPn Mo8wVIK2afeBjL8xT85Vs8a4kygw2o9dqhfPUCeHetUAY+TmWkRKi5VbB JtS1WNsCi4t1Gjl5QX4ucu/V9icwCVHKv5vCqPd0eoGkLsGWoz75tnine p/7XVtcmzKcI/Rr/5KAvUgQSKEjjWpYQXz4dq/CVCSd2MsbUwBdymEDpe ZVcRH2zhBKeE6wdqatnz0SbPsLq7hOfR+TnZYAu7fYczJ7pFz3H0xNpJG g==; X-IronPort-AV: E=McAfee;i="6500,9779,10477"; a="364144338" X-IronPort-AV: E=Sophos;i="5.93,334,1654585200"; d="scan'208";a="364144338" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2022 18:14:28 -0700 X-IronPort-AV: E=Sophos;i="5.93,334,1654585200"; d="scan'208";a="794895421" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Sep 2022 18:14:25 -0700 From: "Huang, Ying" To: Zi Yan Cc: , , Andrew Morton , Yang Shi , Baolin Wang , Oscar Salvador , "Matthew Wilcox" Subject: Re: [RFC 1/6] mm/migrate_pages: separate huge page and normal pages migration References: <20220921060616.73086-1-ying.huang@intel.com> <20220921060616.73086-2-ying.huang@intel.com> <7192F7C6-CA9F-4184-832F-673D2ED5061D@nvidia.com> Date: Thu, 22 Sep 2022 09:14:17 +0800 In-Reply-To: <7192F7C6-CA9F-4184-832F-673D2ED5061D@nvidia.com> (Zi Yan's message of "Wed, 21 Sep 2022 11:55:41 -0400") Message-ID: <87mtasky6u.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Zi, Thank you for comments! Zi Yan writes: > On 21 Sep 2022, at 2:06, Huang Ying wrote: > >> This is a preparation patch to batch the page unmapping and moving for >> the normal pages and THPs. Based on that we can batch the TLB >> shootdown during the page migration and make it possible to use some >> hardware accelerator for the page copying. >> >> In this patch the huge page (PageHuge()) and normal page and THP >> migration is separated in migrate_pages() to make it easy to change >> the normal page and THP migration implementation. >> >> Signed-off-by: "Huang, Ying" >> Cc: Zi Yan >> Cc: Yang Shi >> Cc: Baolin Wang >> Cc: Oscar Salvador >> Cc: Matthew Wilcox >> --- >> mm/migrate.c | 73 +++++++++++++++++++++++++++++++++++++++++++++------- >> 1 file changed, 64 insertions(+), 9 deletions(-) > > Maybe it would be better to have two subroutines for hugetlb migration > and normal page migration respectively. migrate_pages() becomes very > large at this point. Yes. migrate_pages() becomes even larger with this patchset. I will consider more about how to deal with that. I will try the method in your comments in [3/6] for that too. Best Regards, Huang, Ying >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 571d8c9fd5bc..117134f1c6dc 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1414,6 +1414,66 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, >> >> trace_mm_migrate_pages_start(mode, reason); >> >> + for (pass = 0; pass < 10 && retry; pass++) { >> + retry = 0; >> + >> + list_for_each_entry_safe(page, page2, from, lru) { >> + nr_subpages = compound_nr(page); >> + cond_resched(); >> + >> + if (!PageHuge(page)) >> + continue; >> + >> + rc = unmap_and_move_huge_page(get_new_page, >> + put_new_page, private, page, >> + pass > 2, mode, reason, >> + &ret_pages); >> + /* >> + * The rules are: >> + * Success: hugetlb page will be put back >> + * -EAGAIN: stay on the from list >> + * -ENOMEM: stay on the from list >> + * -ENOSYS: stay on the from list >> + * Other errno: put on ret_pages list then splice to >> + * from list >> + */ >> + switch(rc) { >> + case -ENOSYS: >> + /* Hugetlb migration is unsupported */ >> + nr_failed++; >> + nr_failed_pages += nr_subpages; >> + list_move_tail(&page->lru, &ret_pages); >> + break; >> + case -ENOMEM: >> + /* >> + * When memory is low, don't bother to try to migrate >> + * other pages, just exit. >> + */ >> + nr_failed++; >> + nr_failed_pages += nr_subpages + nr_retry_pages; >> + goto out; >> + case -EAGAIN: >> + retry++; >> + nr_retry_pages += nr_subpages; >> + break; >> + case MIGRATEPAGE_SUCCESS: >> + nr_succeeded += nr_subpages; >> + break; >> + default: >> + /* >> + * Permanent failure (-EBUSY, etc.): >> + * unlike -EAGAIN case, the failed page is >> + * removed from migration page list and not >> + * retried in the next outer loop. >> + */ >> + nr_failed++; >> + nr_failed_pages += nr_subpages; >> + break; >> + } >> + } >> + } >> + nr_failed += retry; >> + retry = 1; >> thp_subpage_migration: >> for (pass = 0; pass < 10 && (retry || thp_retry); pass++) { >> retry = 0; >> @@ -1431,18 +1491,14 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, >> cond_resched(); >> >> if (PageHuge(page)) >> - rc = unmap_and_move_huge_page(get_new_page, >> - put_new_page, private, page, >> - pass > 2, mode, reason, >> - &ret_pages); >> - else >> - rc = unmap_and_move(get_new_page, put_new_page, >> + continue; >> + >> + rc = unmap_and_move(get_new_page, put_new_page, >> private, page, pass > 2, mode, >> reason, &ret_pages); >> /* >> * The rules are: >> - * Success: non hugetlb page will be freed, hugetlb >> - * page will be put back >> + * Success: page will be freed >> * -EAGAIN: stay on the from list >> * -ENOMEM: stay on the from list >> * -ENOSYS: stay on the from list >> @@ -1468,7 +1524,6 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, >> nr_thp_split++; >> break; >> } >> - /* Hugetlb migration is unsupported */ >> } else if (!no_subpage_counting) { >> nr_failed++; >> } >> -- >> 2.35.1 > > > -- > Best Regards, > Yan, Zi