From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [PATCH 30/45] vmscan: lumpy pageout Date: Wed, 7 Oct 2009 23:00:47 +0800 Message-ID: <20091007150047.GA9848@localhost> References: <8acda98c0910070338n7220fdabo8c7f8f9e7d21ef6c@mail.gmail.com> <20091007111454.GB15936@localhost> <8acda98c0910070437g1498f99eua9a5ad71e6c2bae4@mail.gmail.com> <20091007132924.GB20855@localhost> <20091007134254.GA26244@localhost> <20091007142054.GA6798@localhost> <8acda98c0910070750x6428b96fgdeee5946d1408888@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andrew Morton , Theodore Tso , Christoph Hellwig , Dave Chinner , Chris Mason , Peter Zijlstra , "Li, Shaohua" , Myklebust Trond , "jens.axboe@oracle.com" , Jan Kara , Nick Piggin , "linux-fsdevel@vger.kernel.org" To: Nikita Danilov Return-path: Received: from mga03.intel.com ([143.182.124.21]:60391 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751233AbZJGPBw (ORCPT ); Wed, 7 Oct 2009 11:01:52 -0400 Content-Disposition: inline In-Reply-To: <8acda98c0910070750x6428b96fgdeee5946d1408888@mail.gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Oct 07, 2009 at 10:50:17PM +0800, Nikita Danilov wrote: > 2009/10/7 Wu Fengguang : >=20 > [...] >=20 > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if (bdi_cap_writ= eback_dirty(mapping->backing_dev_info) && > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 !m= apping->a_ops->writepages) { > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 wbc.range_start =3D (page->index + 1) << PAGE_CACHE_SHIFT; > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 wbc.nr_to_write =3D LUMPY_PAGEOUT_PAGES - 1; > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 generic_writepages(mapping, &wbc); > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 iput(inode); >=20 > I am afraid calling iput() from within pageout code is not generally > safe: it can trigger a lot of file system activity (think > open-unlinked file) that is not supposed to happen in the > direct-reclaim context. Limiting pageout clustering to kswapd might b= e > a better idea---this would improve direct-reclaim latency too, but > still, file systems are not designed for re-entrant calls to iput(). Good point, thanks! --- vmscan: lumpy pageout When pageout a dirty page, try to piggy back more consecutive dirty pages (up to 512KB) to improve IO efficiency. Only ext3/reiserfs which don't have its own aops->writepages are supported in this initial version. CC: Dave Chinner CC: Nikita Danilov Signed-off-by: Wu Fengguang --- mm/page-writeback.c | 12 ++++++++++++ mm/vmscan.c | 20 ++++++++++++++++++++ 2 files changed, 32 insertions(+) --- linux.orig/mm/vmscan.c 2009-10-07 21:39:13.000000000 +0800 +++ linux/mm/vmscan.c 2009-10-07 22:59:57.000000000 +0800 @@ -344,6 +344,8 @@ typedef enum { PAGE_CLEAN, } pageout_t; =20 +#define LUMPY_PAGEOUT_PAGES (512 * 1024 / PAGE_CACHE_SIZE) + /* * pageout is called by shrink_page_list() for each dirty page. * Calls ->writepage(). @@ -398,6 +400,10 @@ static pageout_t pageout(struct page *pa .nonblocking =3D 1, .for_reclaim =3D 1, }; + struct inode *inode =3D NULL; + + if (current_is_kswapd()) + inode =3D igrab(mapping->host); =20 SetPageReclaim(page); res =3D mapping->a_ops->writepage(page, &wbc); @@ -405,10 +411,24 @@ static pageout_t pageout(struct page *pa handle_write_error(mapping, page, res); if (res =3D=3D AOP_WRITEPAGE_ACTIVATE) { ClearPageReclaim(page); + iput(inode); return PAGE_ACTIVATE; } =20 /* + * only write_cache_pages() supports for_reclaim for now + * ignore shmem for now, thanks to Nikita. + */ + if (current_is_kswapd() && + bdi_cap_writeback_dirty(mapping->backing_dev_info) && + !mapping->a_ops->writepages) { + wbc.range_start =3D (page->index + 1) << PAGE_CACHE_SHIFT; + wbc.nr_to_write =3D LUMPY_PAGEOUT_PAGES - 1; + generic_writepages(mapping, &wbc); + iput(inode); + } + + /* * Wait on writeback if requested to. This happens when * direct reclaiming a large contiguous area and the * first attempt to free a range of pages fails. --- linux.orig/mm/page-writeback.c 2009-10-07 21:39:13.000000000 +0800 +++ linux/mm/page-writeback.c 2009-10-07 22:57:55.000000000 +0800 @@ -805,6 +805,11 @@ int write_cache_pages(struct address_spa break; } =20 + if (wbc->for_reclaim && done_index !=3D page->index) { + done =3D 1; + break; + } + if (nr_to_write !=3D wbc->nr_to_write && done_index + WB_SEGMENT_DIST < page->index && --wbc->nr_segments <=3D 0) { @@ -846,6 +851,13 @@ continue_unlock: if (!clear_page_dirty_for_io(page)) goto continue_unlock; =20 + /* + * active and unevictable pages will be checked at + * rotate time + */ + if (wbc->for_reclaim) + SetPageReclaim(page); + ret =3D (*writepage)(page, wbc, data); if (unlikely(ret)) { if (ret =3D=3D AOP_WRITEPAGE_ACTIVATE) { -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html