From patchwork Wed Nov 28 00:42:13 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikulas Patocka X-Patchwork-Id: 10701673 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6D53718B8 for ; Wed, 28 Nov 2018 00:43:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5B71A2C90A for ; Wed, 28 Nov 2018 00:43:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4733F2C921; Wed, 28 Nov 2018 00:43:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A48FD2C91D for ; Wed, 28 Nov 2018 00:43:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726457AbeK1Lmm (ORCPT ); Wed, 28 Nov 2018 06:42:42 -0500 Received: from 109-183-129-149.customers.tmcz.cz ([109.183.129.149]:56966 "EHLO leontynka.twibright.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726500AbeK1Lmm (ORCPT ); Wed, 28 Nov 2018 06:42:42 -0500 Received: from debian.vm ([192.168.192.2]) by leontynka.twibright.com with smtp (Exim 4.89) (envelope-from ) id 1gRnwI-0007s5-Qk; Wed, 28 Nov 2018 01:42:51 +0100 Received: by debian.vm (sSMTP sendmail emulation); Wed, 28 Nov 2018 01:42:50 +0100 Message-Id: <20181128004250.325095242@debian.vm> User-Agent: quilt/0.65 Date: Wed, 28 Nov 2018 01:42:13 +0100 From: Mikulas Patocka To: Jens Axboe Cc: Mike Snitzer , dm-devel@redhat.com, linux-block@vger.kernel.org, "Alasdair G. Kergon" , Christoph Hellwig , Mikulas Patocka Subject: [PATCH 2/3] block: switch to per-cpu in-flight counters MIME-Version: 1.0 Content-Disposition: inline; filename=block-percpu-inflight.patch Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Now when part_round_stats is gone, we can switch to per-cpu in-flight counters. We use the local-atomic type local_t, so that if part_inc_in_flight or part_dec_in_flight is reentrantly called from an interrupt, the value will be correct. The other counters could be corrupted due to reentrant interrupt, but the corruption only results in slight counter skew - the in_flight counter must be exact, so it needs local_t. Signed-off-by: Mikulas Patocka --- block/bio.c | 4 ++-- block/blk-core.c | 4 ++-- block/blk-merge.c | 2 +- block/genhd.c | 47 +++++++++++++++++++++++++++++++++++------------ drivers/md/dm.c | 4 +--- include/linux/genhd.h | 7 ++++--- 6 files changed, 45 insertions(+), 23 deletions(-) Index: linux-block/block/genhd.c =================================================================== --- linux-block.orig/block/genhd.c 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/block/genhd.c 2018-11-28 00:09:59.000000000 +0100 @@ -45,53 +45,76 @@ static void disk_add_events(struct gendi static void disk_del_events(struct gendisk *disk); static void disk_release_events(struct gendisk *disk); -void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int rw) +void part_inc_in_flight(struct request_queue *q, int cpu, struct hd_struct *part, int rw) { if (queue_is_mq(q)) return; - atomic_inc(&part->in_flight[rw]); + local_inc(per_cpu_ptr(part->dkstats, cpu)->in_flight); if (part->partno) - atomic_inc(&part_to_disk(part)->part0.in_flight[rw]); + local_inc(per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight); } -void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, int rw) +void part_dec_in_flight(struct request_queue *q, int cpu, struct hd_struct *part, int rw) { if (queue_is_mq(q)) return; - atomic_dec(&part->in_flight[rw]); + local_dec(per_cpu_ptr(part->dkstats, cpu)->in_flight); if (part->partno) - atomic_dec(&part_to_disk(part)->part0.in_flight[rw]); + local_dec(per_cpu_ptr(part_to_disk(part)->part0.dkstats, cpu)->in_flight); } void part_in_flight(struct request_queue *q, struct hd_struct *part, unsigned int inflight[2]) { + int cpu; + if (queue_is_mq(q)) { blk_mq_in_flight(q, part, inflight); return; } - inflight[0] = atomic_read(&part->in_flight[0]) + - atomic_read(&part->in_flight[1]); + inflight[0] = 0; + for_each_possible_cpu(cpu) { + inflight[0] += local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[0]) + + local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[1]); + } + if ((int)inflight[0] < 0) + inflight[0] = 0; + if (part->partno) { part = &part_to_disk(part)->part0; - inflight[1] = atomic_read(&part->in_flight[0]) + - atomic_read(&part->in_flight[1]); + inflight[1] = 0; + for_each_possible_cpu(cpu) { + inflight[1] += local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[0]) + + local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[1]); + } + if ((int)inflight[1] < 0) + inflight[1] = 0; } } void part_in_flight_rw(struct request_queue *q, struct hd_struct *part, unsigned int inflight[2]) { + int cpu; + if (queue_is_mq(q)) { blk_mq_in_flight_rw(q, part, inflight); return; } - inflight[0] = atomic_read(&part->in_flight[0]); - inflight[1] = atomic_read(&part->in_flight[1]); + inflight[0] = 0; + inflight[1] = 0; + for_each_possible_cpu(cpu) { + inflight[0] += local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[0]); + inflight[1] += local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[1]); + } + if ((int)inflight[0] < 0) + inflight[0] = 0; + if ((int)inflight[1] < 0) + inflight[1] = 0; } struct hd_struct *__disk_get_part(struct gendisk *disk, int partno) Index: linux-block/include/linux/genhd.h =================================================================== --- linux-block.orig/include/linux/genhd.h 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/include/linux/genhd.h 2018-11-28 00:09:59.000000000 +0100 @@ -17,6 +17,7 @@ #include #include #include +#include #ifdef CONFIG_BLOCK @@ -89,6 +90,7 @@ struct disk_stats { unsigned long merges[NR_STAT_GROUPS]; unsigned long io_ticks; unsigned long time_in_queue; + local_t in_flight[2]; }; #define PARTITION_META_INFO_VOLNAMELTH 64 @@ -122,7 +124,6 @@ struct hd_struct { int make_it_fail; #endif unsigned long stamp; - atomic_t in_flight[2]; #ifdef CONFIG_SMP struct disk_stats __percpu *dkstats; #else @@ -380,9 +381,9 @@ void part_in_flight(struct request_queue unsigned int inflight[2]); void part_in_flight_rw(struct request_queue *q, struct hd_struct *part, unsigned int inflight[2]); -void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, +void part_dec_in_flight(struct request_queue *q, int cpu, struct hd_struct *part, int rw); -void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, +void part_inc_in_flight(struct request_queue *q, int cpu, struct hd_struct *part, int rw); static inline struct partition_meta_info *alloc_part_info(struct gendisk *disk) Index: linux-block/block/bio.c =================================================================== --- linux-block.orig/block/bio.c 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/block/bio.c 2018-11-28 00:09:59.000000000 +0100 @@ -1688,7 +1688,7 @@ void generic_start_io_acct(struct reques update_io_ticks(cpu, part, jiffies); part_stat_inc(cpu, part, ios[sgrp]); part_stat_add(cpu, part, sectors[sgrp], sectors); - part_inc_in_flight(q, part, op_is_write(op)); + part_inc_in_flight(q, cpu, part, op_is_write(op)); part_stat_unlock(); } @@ -1707,7 +1707,7 @@ void generic_end_io_acct(struct request_ part_stat_add(cpu, part, time_in_queue, duration); if (part->partno) part_stat_add(cpu, &part_to_disk(part)->part0, time_in_queue, duration); - part_dec_in_flight(q, part, op_is_write(req_op)); + part_dec_in_flight(q, cpu, part, op_is_write(req_op)); part_stat_unlock(); } Index: linux-block/block/blk-merge.c =================================================================== --- linux-block.orig/block/blk-merge.c 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/block/blk-merge.c 2018-11-28 00:09:59.000000000 +0100 @@ -690,7 +690,7 @@ static void blk_account_io_merge(struct cpu = part_stat_lock(); part = req->part; - part_dec_in_flight(req->q, part, rq_data_dir(req)); + part_dec_in_flight(req->q, cpu, part, rq_data_dir(req)); hd_struct_put(part); part_stat_unlock(); Index: linux-block/block/blk-core.c =================================================================== --- linux-block.orig/block/blk-core.c 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/block/blk-core.c 2018-11-28 00:09:59.000000000 +0100 @@ -1356,7 +1356,7 @@ void blk_account_io_done(struct request part_stat_add(cpu, part, nsecs[sgrp], now - req->start_time_ns); part_stat_add(cpu, part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); part_stat_add(cpu, &part_to_disk(part)->part0, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); - part_dec_in_flight(req->q, part, rq_data_dir(req)); + part_dec_in_flight(req->q, cpu, part, rq_data_dir(req)); hd_struct_put(part); part_stat_unlock(); @@ -1391,7 +1391,7 @@ void blk_account_io_start(struct request part = &rq->rq_disk->part0; hd_struct_get(part); } - part_inc_in_flight(rq->q, part, rw); + part_inc_in_flight(rq->q, cpu, part, rw); rq->part = part; } Index: linux-block/drivers/md/dm.c =================================================================== --- linux-block.orig/drivers/md/dm.c 2018-11-28 00:09:59.000000000 +0100 +++ linux-block/drivers/md/dm.c 2018-11-28 00:09:59.000000000 +0100 @@ -663,8 +663,7 @@ static void start_io_acct(struct dm_io * generic_start_io_acct(md->queue, bio_op(bio), bio_sectors(bio), &dm_disk(md)->part0); - atomic_set(&dm_disk(md)->part0.in_flight[rw], - atomic_inc_return(&md->pending[rw])); + atomic_inc(&md->pending[rw]); if (unlikely(dm_stats_used(&md->stats))) dm_stats_account_io(&md->stats, bio_data_dir(bio), @@ -693,7 +692,6 @@ static void end_io_acct(struct dm_io *io * a flush. */ pending = atomic_dec_return(&md->pending[rw]); - atomic_set(&dm_disk(md)->part0.in_flight[rw], pending); pending += atomic_read(&md->pending[rw^0x1]); /* nudge anyone waiting on suspend queue */