From patchwork Tue Jan 9 07:13:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13514342 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F11548F52; Tue, 9 Jan 2024 07:16:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4T8Mg66JCwz4f3jq6; Tue, 9 Jan 2024 15:16:34 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id C5D991A01A9; Tue, 9 Jan 2024 15:16:36 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgBnOBHS8pxl4SM0AQ--.32279S4; Tue, 09 Jan 2024 15:16:36 +0800 (CST) From: Yu Kuai To: ming.lei@redhat.com, hch@lst.de, bvanassche@acm.org, axboe@kernel.dk Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH for-6.8/block] block: support to account io_ticks precisely Date: Tue, 9 Jan 2024 15:13:32 +0800 Message-Id: <20240109071332.2216253-1-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgBnOBHS8pxl4SM0AQ--.32279S4 X-Coremail-Antispam: 1UD129KBjvJXoWfJr43Kr17ZrWxWFWDWFWxZwb_yoWkXF4xp3 yDAF47ta40gF48uFykta43J3Wagw4vkr47Ar43CryYyFnrKr1fZ3WvvFWYqF4xZrZ7AayU Zr48AayDC398W3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvY14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v2 6r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0J UdHUDUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ From: Yu Kuai Currently, io_ticks is accounted based on sampling, specifically update_io_ticks() will always account io_ticks by 1 jiffies from bdev_start_io_acct()/blk_account_io_start(), and the result can be inaccurate, for example(HZ is 250): Test script: fio -filename=/dev/sda -bs=4k -rw=write -direct=1 -name=test -thinktime=4ms Test result: util is about 90%, while the disk is really idle. In order to account io_ticks precisely, update_io_ticks() must know if there are IO inflight already, and this requires overhead slightly, hence precise io accounting is disabled by default, and user can enable it through sysfs entry. Noted that for rq-based devcie, part_stat_local_inc/dec() and part_in_flight() is used to track inflight instead of iterating tags, which is not supposed to be used in fast path because 'tags->lock' is grabbed in blk_mq_find_and_get_req(). Signed-off-by: Yu Kuai --- Changes from RFC v1: - remove the new parameter for update_io_ticks(); - simplify update_io_ticks(); - use swith in queue_iostats_store(); - add missing part_stat_local_dec() in blk_account_io_merge_request(); Changes from RFC v2: - fix that precise is ignored for the first io in update_io_ticks(); Documentation/ABI/stable/sysfs-block | 8 ++++-- block/blk-core.c | 10 +++++-- block/blk-merge.c | 3 ++ block/blk-mq-debugfs.c | 2 ++ block/blk-mq.c | 11 +++++++- block/blk-sysfs.c | 42 ++++++++++++++++++++++++++-- block/blk.h | 1 + block/genhd.c | 2 +- include/linux/blk-mq.h | 1 + include/linux/blkdev.h | 3 ++ 10 files changed, 74 insertions(+), 9 deletions(-) diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block index 1fe9a553c37b..79027bf2661a 100644 --- a/Documentation/ABI/stable/sysfs-block +++ b/Documentation/ABI/stable/sysfs-block @@ -358,8 +358,12 @@ What: /sys/block//queue/iostats Date: January 2009 Contact: linux-block@vger.kernel.org Description: - [RW] This file is used to control (on/off) the iostats - accounting of the disk. + [RW] This file is used to control the iostats accounting of the + disk. If this value is 0, iostats accounting is disabled; If + this value is 1, iostats accounting is enabled, but io_ticks is + accounted by sampling and the result is not accurate; If this + value is 2, iostats accounting is enabled and io_ticks is + accounted precisely, but there will be slightly more overhead. What: /sys/block//queue/logical_block_size diff --git a/block/blk-core.c b/block/blk-core.c index 9520ccab3050..c70dc311e3b7 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -954,11 +954,15 @@ EXPORT_SYMBOL_GPL(iocb_bio_iopoll); void update_io_ticks(struct block_device *part, unsigned long now, bool end) { unsigned long stamp; + bool precise = blk_queue_precise_io_stat(part->bd_queue); again: stamp = READ_ONCE(part->bd_stamp); - if (unlikely(time_after(now, stamp))) { - if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) - __part_stat_add(part, io_ticks, end ? now - stamp : 1); + if (unlikely(time_after(now, stamp)) && + likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) { + if (end || (precise && part_in_flight(part))) + __part_stat_add(part, io_ticks, now - stamp); + else if (!precise) + __part_stat_add(part, io_ticks, 1); } if (part->bd_partno) { part = bdev_whole(part); diff --git a/block/blk-merge.c b/block/blk-merge.c index 2d470cf2173e..ea5553766f90 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -779,6 +779,9 @@ static void blk_account_io_merge_request(struct request *req) if (blk_do_io_stat(req)) { part_stat_lock(); part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); + if (req->rq_flags & RQF_PRECISE_IO_STAT) + part_stat_local_dec(req->part, + in_flight[op_is_write(req_op(req))]); part_stat_unlock(); } } diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 5cbeb9344f2f..4d745fc07a8a 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -86,6 +86,7 @@ static const char *const blk_queue_flag_name[] = { QUEUE_FLAG_NAME(FAIL_IO), QUEUE_FLAG_NAME(NONROT), QUEUE_FLAG_NAME(IO_STAT), + QUEUE_FLAG_NAME(PRECISE_IO_STAT), QUEUE_FLAG_NAME(NOXMERGES), QUEUE_FLAG_NAME(ADD_RANDOM), QUEUE_FLAG_NAME(SYNCHRONOUS), @@ -252,6 +253,7 @@ static const char *const rqf_name[] = { RQF_NAME(FAILED), RQF_NAME(QUIET), RQF_NAME(IO_STAT), + RQF_NAME(PRECISE_IO_STAT), RQF_NAME(PM), RQF_NAME(HASHED), RQF_NAME(STATS), diff --git a/block/blk-mq.c b/block/blk-mq.c index fb29ff5cc281..5b82bafbb740 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -360,8 +360,11 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, if (data->flags & BLK_MQ_REQ_PM) data->rq_flags |= RQF_PM; - if (blk_queue_io_stat(q)) + if (blk_queue_io_stat(q)) { data->rq_flags |= RQF_IO_STAT; + if (blk_queue_precise_io_stat(q)) + data->rq_flags |= RQF_PRECISE_IO_STAT; + } rq->rq_flags = data->rq_flags; if (data->rq_flags & RQF_SCHED_TAGS) { @@ -999,6 +1002,9 @@ static inline void blk_account_io_done(struct request *req, u64 now) update_io_ticks(req->part, jiffies, true); part_stat_inc(req->part, ios[sgrp]); part_stat_add(req->part, nsecs[sgrp], now - req->start_time_ns); + if (req->rq_flags & RQF_PRECISE_IO_STAT) + part_stat_local_dec(req->part, + in_flight[op_is_write(req_op(req))]); part_stat_unlock(); } } @@ -1021,6 +1027,9 @@ static inline void blk_account_io_start(struct request *req) part_stat_lock(); update_io_ticks(req->part, jiffies, false); + if (req->rq_flags & RQF_PRECISE_IO_STAT) + part_stat_local_inc(req->part, + in_flight[op_is_write(req_op(req))]); part_stat_unlock(); } } diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 40bab5975c56..3753fc28d467 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -303,7 +303,6 @@ queue_##name##_store(struct request_queue *q, const char *page, size_t count) \ QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1); QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0); -QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0); QUEUE_SYSFS_BIT_FNS(stable_writes, STABLE_WRITES, 0); #undef QUEUE_SYSFS_BIT_FNS @@ -468,6 +467,45 @@ static ssize_t queue_dax_show(struct request_queue *q, char *page) return queue_var_show(blk_queue_dax(q), page); } +static ssize_t queue_iostats_show(struct request_queue *q, char *page) +{ + int val = 0; + + if (blk_queue_io_stat(q)) + val = blk_queue_precise_io_stat(q) ? 2 : 1; + + return queue_var_show(val, page); +} + +static ssize_t +queue_iostats_store(struct request_queue *q, const char *page, size_t count) +{ + unsigned long nr; + int ret = queue_var_store(&nr, page, count); + + if (ret < 0) + return ret; + + switch (nr) { + case 0: + blk_queue_flag_clear(QUEUE_FLAG_IO_STAT, q); + blk_queue_flag_clear(QUEUE_FLAG_PRECISE_IO_STAT, q); + break; + case 1: + blk_queue_flag_set(QUEUE_FLAG_IO_STAT, q); + blk_queue_flag_clear(QUEUE_FLAG_PRECISE_IO_STAT, q); + break; + case 2: + blk_queue_flag_set(QUEUE_FLAG_IO_STAT, q); + blk_queue_flag_set(QUEUE_FLAG_PRECISE_IO_STAT, q); + break; + default: + return -EINVAL; + } + + return count; +} + #define QUEUE_RO_ENTRY(_prefix, _name) \ static struct queue_sysfs_entry _prefix##_entry = { \ .attr = { .name = _name, .mode = 0444 }, \ @@ -489,6 +527,7 @@ QUEUE_RO_ENTRY(queue_max_segments, "max_segments"); QUEUE_RO_ENTRY(queue_max_integrity_segments, "max_integrity_segments"); QUEUE_RO_ENTRY(queue_max_segment_size, "max_segment_size"); QUEUE_RW_ENTRY(elv_iosched, "scheduler"); +QUEUE_RW_ENTRY(queue_iostats, "iostats"); QUEUE_RO_ENTRY(queue_logical_block_size, "logical_block_size"); QUEUE_RO_ENTRY(queue_physical_block_size, "physical_block_size"); @@ -534,7 +573,6 @@ static struct queue_sysfs_entry queue_hw_sector_size_entry = { }; QUEUE_RW_ENTRY(queue_nonrot, "rotational"); -QUEUE_RW_ENTRY(queue_iostats, "iostats"); QUEUE_RW_ENTRY(queue_random, "add_random"); QUEUE_RW_ENTRY(queue_stable_writes, "stable_writes"); diff --git a/block/blk.h b/block/blk.h index 1ef920f72e0f..1154e87a4022 100644 --- a/block/blk.h +++ b/block/blk.h @@ -344,6 +344,7 @@ static inline bool blk_do_io_stat(struct request *rq) } void update_io_ticks(struct block_device *part, unsigned long now, bool end); +unsigned int part_in_flight(struct block_device *part); static inline void req_set_nomerge(struct request_queue *q, struct request *req) { diff --git a/block/genhd.c b/block/genhd.c index d74fb5b4ae68..92d03cd24c79 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -118,7 +118,7 @@ static void part_stat_read_all(struct block_device *part, } } -static unsigned int part_in_flight(struct block_device *part) +unsigned int part_in_flight(struct block_device *part) { unsigned int inflight = 0; int cpu; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index a676e116085f..bd925421bc4a 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -44,6 +44,7 @@ typedef __u32 __bitwise req_flags_t; #define RQF_QUIET ((__force req_flags_t)(1 << 11)) /* account into disk and partition IO statistics */ #define RQF_IO_STAT ((__force req_flags_t)(1 << 13)) +#define RQF_PRECISE_IO_STAT ((__force req_flags_t)(1 << 14)) /* runtime pm request */ #define RQF_PM ((__force req_flags_t)(1 << 15)) /* on IO scheduler merge hash */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e1e705aef51e..81c9784baff2 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -516,6 +516,7 @@ struct request_queue { #define QUEUE_FLAG_NONROT 6 /* non-rotational device (SSD) */ #define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */ #define QUEUE_FLAG_IO_STAT 7 /* do disk/partitions IO accounting */ +#define QUEUE_FLAG_PRECISE_IO_STAT 8 /* do disk/partitions IO accounting precisely */ #define QUEUE_FLAG_NOXMERGES 9 /* No extended merges */ #define QUEUE_FLAG_ADD_RANDOM 10 /* Contributes to random pool */ #define QUEUE_FLAG_SYNCHRONOUS 11 /* always completes in submit context */ @@ -556,6 +557,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); #define blk_queue_stable_writes(q) \ test_bit(QUEUE_FLAG_STABLE_WRITES, &(q)->queue_flags) #define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags) +#define blk_queue_precise_io_stat(q) \ + test_bit(QUEUE_FLAG_PRECISE_IO_STAT, &(q)->queue_flags) #define blk_queue_add_random(q) test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags) #define blk_queue_zone_resetall(q) \ test_bit(QUEUE_FLAG_ZONE_RESETALL, &(q)->queue_flags)