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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8E13C433EF for ; Tue, 26 Apr 2022 01:58:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 266A56B0073; Mon, 25 Apr 2022 21:58:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 215456B0074; Mon, 25 Apr 2022 21:58:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0BADB6B0075; Mon, 25 Apr 2022 21:58:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id EFEF16B0073 for ; Mon, 25 Apr 2022 21:58:45 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id CD78021D9E for ; Tue, 26 Apr 2022 01:58:45 +0000 (UTC) X-FDA: 79397371410.28.4A9DB3E Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf31.hostedemail.com (Postfix) with ESMTP id 15FAC20047 for ; Tue, 26 Apr 2022 01:58:37 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id E2B46210E6; Tue, 26 Apr 2022 01:58:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1650938323; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=W56qHWh5atZr7qX9LectLL9QyYdxoZqmGcchx2rNVB4=; b=ogqpgOIm+QovqHgwGLsn9RVn9CyEzzokAjwoArjc0FitdWnkOX8V4EN9eIa5JXd1zom9/w BKmc/0RNe4fQgG/geFApwuWx0c+ez1vhbzfb6Gl41N3OXAXS0rOg58JN+oTJLKnnwDm/RM MlqqJbvANe/Nq9sY4aQCB9pAuWLHQ0o= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1650938323; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=W56qHWh5atZr7qX9LectLL9QyYdxoZqmGcchx2rNVB4=; b=BuMEFM+hfm66Z/j3I5avfIiqZkmeyrUkcBGq3lyfGbZ51Qxqd0VwInnFDlXpWOuEdZuGgc PtQcE7PMEG1QHFBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id A75BD13A97; Tue, 26 Apr 2022 01:58:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id VfdrGNFRZ2LhDgAAMHmgww (envelope-from ); Tue, 26 Apr 2022 01:58:41 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 From: "NeilBrown" To: "Miaohe Lin" Cc: "Christoph Hellwig" , "David Howells" , linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Andrew Morton" Subject: Re: [PATCH 09/10] MM: submit multipage write for SWP_FS_OPS swap-space In-reply-to: <033ccf1a-c6b5-fd77-0ad0-4915ff07bc15@huawei.com> References: <164859751830.29473.5309689752169286816.stgit@noble.brown>, <164859778128.29473.5191868522654408537.stgit@noble.brown>, <033ccf1a-c6b5-fd77-0ad0-4915ff07bc15@huawei.com> Date: Tue, 26 Apr 2022 11:58:37 +1000 Message-id: <165093831774.1648.3187486020864614234@noble.neil.brown.name> Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=ogqpgOIm; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=BuMEFM+h; spf=pass (imf31.hostedemail.com: domain of neilb@suse.de designates 195.135.220.28 as permitted sender) smtp.mailfrom=neilb@suse.de; dmarc=pass (policy=none) header.from=suse.de X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 15FAC20047 X-Stat-Signature: 79ix6ui9rioedqa8ards3czou4hwkgaa X-HE-Tag: 1650938317-29385 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 18 Apr 2022, Miaohe Lin wrote: > On 2022/3/30 7:49, NeilBrown wrote: > > swap_writepage() is given one page at a time, but may be called repeatedly > > in succession. > > For block-device swapspace, the blk_plug functionality allows the > > multiple pages to be combined together at lower layers. > > That cannot be used for SWP_FS_OPS as blk_plug may not exist - it is > > only active when CONFIG_BLOCK=3Dy. Consequently all swap reads over NFS > > are single page reads. > >=20 > > With this patch we pass a pointer-to-pointer via the wbc. > > swap_writepage can store state between calls - much like the pointer > > passed explicitly to swap_readpage. After calling swap_writepage() some > > number of times, the state will be passed to swap_write_unplug() which > > can submit the combined request. > >=20 > > Reviewed-by: Christoph Hellwig > > Signed-off-by: NeilBrown > ... > > =20 > > static int swap_writepage_fs(struct page *page, struct writeback_control= *wbc) > > { > > - struct swap_iocb *sio; > > + struct swap_iocb *sio =3D NULL; > > struct swap_info_struct *sis =3D page_swap_info(page); > > struct file *swap_file =3D sis->swap_file; > > - struct address_space *mapping =3D swap_file->f_mapping; > > - struct iov_iter from; > > - int ret; > > + loff_t pos =3D page_file_offset(page); > > =20 > > set_page_writeback(page); > > unlock_page(page); > > - sio =3D mempool_alloc(sio_pool, GFP_NOIO); > > - init_sync_kiocb(&sio->iocb, swap_file); > > - sio->iocb.ki_complete =3D sio_write_complete; > > - sio->iocb.ki_pos =3D page_file_offset(page); > > - sio->bvec[0].bv_page =3D page; > > - sio->bvec[0].bv_len =3D PAGE_SIZE; > > - sio->bvec[0].bv_offset =3D 0; > > - iov_iter_bvec(&from, WRITE, &sio->bvec[0], 1, PAGE_SIZE); > > - ret =3D mapping->a_ops->swap_rw(&sio->iocb, &from); > > - if (ret !=3D -EIOCBQUEUED) > > - sio_write_complete(&sio->iocb, ret); > > - return ret; > > + if (wbc->swap_plug) > > + sio =3D *wbc->swap_plug; > > + if (sio) { > > + if (sio->iocb.ki_filp !=3D swap_file || > > + sio->iocb.ki_pos + sio->pages * PAGE_SIZE !=3D pos) { > > + swap_write_unplug(sio); > > + sio =3D NULL; > > + } > > + } > > + if (!sio) { > > + sio =3D mempool_alloc(sio_pool, GFP_NOIO); > > + init_sync_kiocb(&sio->iocb, swap_file); > > + sio->iocb.ki_complete =3D sio_write_complete; > > + sio->iocb.ki_pos =3D pos; > > + sio->pages =3D 0; > > + } > > + sio->bvec[sio->pages].bv_page =3D page; > > + sio->bvec[sio->pages].bv_len =3D PAGE_SIZE; >=20 > Many thanks for your patch. And sorry for late responding and newbie questi= on. Does swap_writepage_fs > support transhuge page now? We could come across transhuge page here. But b= v_len =3D=3D PAGE_SIZE and pages > =3D=3D 1 is assumed here. Do we need something like below: >=20 > sio->bvec[sio->pages].bv_len =3D thp_size(page); > sio->pages +=3D thp_nr_pages(page); Yes, that probably makes sense. I'll have a closer look and maybe resend later this week. Thanks, NeilBrown >=20 > Thanks! :) >=20 > > + sio->bvec[sio->pages].bv_offset =3D 0; > ... > > . > >=20 >=20 >=20