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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CC30C636CA for ; Thu, 15 Jul 2021 18:52:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81AA6613C4 for ; Thu, 15 Jul 2021 18:52:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241357AbhGOSyS (ORCPT ); Thu, 15 Jul 2021 14:54:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52636 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239773AbhGOSuZ (ORCPT ); Thu, 15 Jul 2021 14:50:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8F1F2613D0; Thu, 15 Jul 2021 18:47:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626374852; bh=zIOGho+xru4zoi4b+B/R8U5ZpRrPePcpzgoepV2FLus=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hMhEINag088GwdseXLKFW3wsWefAKEO7DnfzV5LK6AheI3yc2DwhTti3ZItRySIEU O+MCadchNe53oWdT5sAH+y+0oxan5STujXADPWeQxbKHQBKjYkTH0mkmekehzTYV4s NWCI9dZSPTvaoSnS/MTAUjf8Plh41K/VysIm+RuY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Mike Snitzer , Sasha Levin Subject: [PATCH 5.10 052/215] dm writecache: dont split bios when overwriting contiguous cache content Date: Thu, 15 Jul 2021 20:37:04 +0200 Message-Id: <20210715182608.597407892@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210715182558.381078833@linuxfoundation.org> References: <20210715182558.381078833@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikulas Patocka [ Upstream commit ee50cc19d80e9b9a8283d1fb517a778faf2f6899 ] If dm-writecache overwrites existing cached data, it splits the incoming bio into many block-sized bios. The I/O scheduler does merge these bios into one large request but this needless splitting and merging causes performance degradation. Fix this by avoiding bio splitting if the cache target area that is being overwritten is contiguous. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin --- drivers/md/dm-writecache.c | 38 ++++++++++++++++++++++++++++++-------- 1 file changed, 30 insertions(+), 8 deletions(-) diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 8628c4aa2e85..64c2980aaa54 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -1360,14 +1360,18 @@ read_next_block: } else { do { bool found_entry = false; + bool search_used = false; if (writecache_has_error(wc)) goto unlock_error; e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0); if (e) { - if (!writecache_entry_is_committed(wc, e)) + if (!writecache_entry_is_committed(wc, e)) { + search_used = true; goto bio_copy; + } if (!WC_MODE_PMEM(wc) && !e->write_in_progress) { wc->overwrote_committed = true; + search_used = true; goto bio_copy; } found_entry = true; @@ -1404,13 +1408,31 @@ bio_copy: sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT); while (bio_size < bio->bi_iter.bi_size) { - struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec); - if (!f) - break; - write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector + - (bio_size >> SECTOR_SHIFT), wc->seq_count); - writecache_insert_entry(wc, f); - wc->uncommitted_blocks++; + if (!search_used) { + struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec); + if (!f) + break; + write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector + + (bio_size >> SECTOR_SHIFT), wc->seq_count); + writecache_insert_entry(wc, f); + wc->uncommitted_blocks++; + } else { + struct wc_entry *f; + struct rb_node *next = rb_next(&e->rb_node); + if (!next) + break; + f = container_of(next, struct wc_entry, rb_node); + if (f != e + 1) + break; + if (read_original_sector(wc, f) != + read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT)) + break; + if (unlikely(f->write_in_progress)) + break; + if (writecache_entry_is_committed(wc, f)) + wc->overwrote_committed = true; + e = f; + } bio_size += wc->block_size; current_cache_sec += wc->block_size >> SECTOR_SHIFT; } -- 2.30.2