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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 BFD70C7618F for ; Wed, 24 Jul 2019 21:35:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BB712147A for ; Wed, 24 Jul 2019 21:35:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="D6p/PrBk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726087AbfGXVfe (ORCPT ); Wed, 24 Jul 2019 17:35:34 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:42732 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728975AbfGXVfd (ORCPT ); Wed, 24 Jul 2019 17:35:33 -0400 Received: by mail-wr1-f68.google.com with SMTP id x1so33498162wrr.9; Wed, 24 Jul 2019 14:35:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=j4tIopvAHkt6FY4+Y6Lo4ek2c4j4aI85q+AB/SfNRnc=; b=D6p/PrBkf2krwRDhBuggO0pHzDW+CSh8oL9w/WHeL78RBaY91ZrNOSjRmb2SBBv/Kq qkMTxBTl1Q+Y4etncnKwowcc5fYK465lgufSAKjZXFXm/Vv1hgLyRKP/SZpCFQgeUd6Q 11V8Cr56cPFUbr0f0DNujBVWnUSfI6LiyMKt2uAKoD3f/P65/lPdMIdPeETkK4gEwv3/ 0itvG89pKiXuChSkAFScMn1y26v2qbAqmnu34m5V1hUaCFsbYRc7MvL0wGpX8dL50EHa 6fMBcTlui8Q0XTQp2vNt+cEtYmRWvJ0b4eOsjN2TyzEIFySu/3i7fqe4fIpRMszFDV3r YbGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=j4tIopvAHkt6FY4+Y6Lo4ek2c4j4aI85q+AB/SfNRnc=; b=NVe2v+Mv9LsbX9DYCfcY4pamm6wOUCQdrbwBteJtQ/l//nXnNbiV1CEtWhYBa+h8rc W42Nv9sfQ3mkhbFRGPobsxHRNghUy2BCD/0apzYeyolI3QkbxCsN6W0CG2yHT/Yk53gL yiUpYhdipd6UGOaJBP6jmvzLpkHhkFwLSqT9d1aWjR3sqH6Lwwc0PVVRVMtuvbrL+hhR B+07Nr57ksZQuC19u1z69/s9KzCY7Q5K4hjMxKj4yZ6yUbAapKjm6JQRVn4PlVBGoZ4T nrjBs3z/bo+AXHLdxvxVPpGrcvZP1rNr95AQZrW2z3hgAZoGR38Axt41LlVGHl35XcIx DPEw== X-Gm-Message-State: APjAAAX+ouXIkqrdzPwSlFOOA0aVuI5Z+94XQ3234vK87npnQOI0QYVc VXwtLPpuOcFTDEdpTw7HWjQr48tEvZc= X-Google-Smtp-Source: APXvYqwQ73lwEU3624dO60K7D8kB608876TJQjODVoYvDQh1fzmClfqiIYiati0TxV5Xo1EO4kcD8A== X-Received: by 2002:a05:6000:4b:: with SMTP id k11mr86584228wrx.82.1564004132132; Wed, 24 Jul 2019 14:35:32 -0700 (PDT) Received: from localhost.localdomain ([109.126.147.168]) by smtp.gmail.com with ESMTPSA id u186sm80799083wmu.26.2019.07.24.14.35.30 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 14:35:31 -0700 (PDT) From: "Pavel Begunkov (Silence)" To: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, josef@toxicpanda.com Cc: Pavel Begunkov Subject: [RESEND RFC PATCH 1/2] blk-iolatency: Fix zero mean in previous stats Date: Thu, 25 Jul 2019 00:35:09 +0300 Message-Id: <0b930bf6ebcc309748419877eb34fe50cb747299.1560510935.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Message-ID: <20190724213509.GMlLgUy1dH9wi13EQn8RWJ7sTghjmObwzujqasPwSnc@z> From: Pavel Begunkov struct blk_rq_stat has two implicit states in which it can be: (1) per-cpu intermediate stats (i.e. staging, intermediate) (2) final stats / aggregation of (1) (see blk_rq_stat_collect) The states use different sets of fields. E.g. (1) uses @batch but not @mean, and vise versa for (2). So, any function that uses struct blk_rq_stat has implicit assumptions about the states. blk_rq_stat_sum() expects @src to be in (1) and @dst in (2). iolatency_check_latencies() violates that (passing struct blk_rq_stat, previously used as @dst, as @src). As a result, iolat->cur_stat.rqs.mean is always 0 for non-ssd devices. Use 2 distinct functions instead: one to collect intermediate stats (i.e. with valid batch), and the second one for merging already accumulated stats (i.e. with valid mean). Signed-off-by: Pavel Begunkov --- block/blk-iolatency.c | 21 ++++++++++++++++----- block/blk-stat.c | 20 ++++++++++++++++++-- block/blk-stat.h | 3 ++- 3 files changed, 36 insertions(+), 8 deletions(-) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index d22e61bced86..fc8ce1a0ae21 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -199,7 +199,7 @@ static inline void latency_stat_init(struct iolatency_grp *iolat, blk_rq_stat_init(&stat->rqs); } -static inline void latency_stat_sum(struct iolatency_grp *iolat, +static inline void latency_stat_merge(struct iolatency_grp *iolat, struct latency_stat *sum, struct latency_stat *stat) { @@ -207,7 +207,18 @@ static inline void latency_stat_sum(struct iolatency_grp *iolat, sum->ps.total += stat->ps.total; sum->ps.missed += stat->ps.missed; } else - blk_rq_stat_sum(&sum->rqs, &stat->rqs); + blk_rq_stat_merge(&sum->rqs, &stat->rqs); +} + +static inline void latency_stat_collect(struct iolatency_grp *iolat, + struct latency_stat *sum, + struct latency_stat *stat) +{ + if (iolat->ssd) { + sum->ps.total += stat->ps.total; + sum->ps.missed += stat->ps.missed; + } else + blk_rq_stat_collect(&sum->rqs, &stat->rqs); } static inline void latency_stat_record_time(struct iolatency_grp *iolat, @@ -531,7 +542,7 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) for_each_online_cpu(cpu) { struct latency_stat *s; s = per_cpu_ptr(iolat->stats, cpu); - latency_stat_sum(iolat, &stat, s); + latency_stat_collect(iolat, &stat, s); latency_stat_init(iolat, s); } preempt_enable(); @@ -552,7 +563,7 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) /* Somebody beat us to the punch, just bail. */ spin_lock_irqsave(&lat_info->lock, flags); - latency_stat_sum(iolat, &iolat->cur_stat, &stat); + latency_stat_merge(iolat, &iolat->cur_stat, &stat); lat_info->nr_samples -= iolat->nr_samples; lat_info->nr_samples += latency_stat_samples(iolat, &iolat->cur_stat); iolat->nr_samples = latency_stat_samples(iolat, &iolat->cur_stat); @@ -913,7 +924,7 @@ static size_t iolatency_ssd_stat(struct iolatency_grp *iolat, char *buf, for_each_online_cpu(cpu) { struct latency_stat *s; s = per_cpu_ptr(iolat->stats, cpu); - latency_stat_sum(iolat, &stat, s); + latency_stat_collect(iolat, &stat, s); } preempt_enable(); diff --git a/block/blk-stat.c b/block/blk-stat.c index 940f15d600f8..78389182b5d0 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -26,7 +26,7 @@ void blk_rq_stat_init(struct blk_rq_stat *stat) } /* src is a per-cpu stat, mean isn't initialized */ -void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) +void blk_rq_stat_collect(struct blk_rq_stat *dst, struct blk_rq_stat *src) { if (!src->nr_samples) return; @@ -40,6 +40,21 @@ void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) dst->nr_samples += src->nr_samples; } +void blk_rq_stat_merge(struct blk_rq_stat *dst, struct blk_rq_stat *src) +{ + if (!src->nr_samples) + return; + + dst->min = min(dst->min, src->min); + dst->max = max(dst->max, src->max); + + dst->mean = div_u64(src->mean * src->nr_samples + + dst->mean * dst->nr_samples, + dst->nr_samples + src->nr_samples); + + dst->nr_samples += src->nr_samples; +} + void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value) { stat->min = min(stat->min, value); @@ -90,7 +105,8 @@ static void blk_stat_timer_fn(struct timer_list *t) cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); for (bucket = 0; bucket < cb->buckets; bucket++) { - blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); + blk_rq_stat_collect(&cb->stat[bucket], + &cpu_stat[bucket]); blk_rq_stat_init(&cpu_stat[bucket]); } } diff --git a/block/blk-stat.h b/block/blk-stat.h index 17b47a86eefb..5597ecc34ef5 100644 --- a/block/blk-stat.h +++ b/block/blk-stat.h @@ -165,7 +165,8 @@ static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb, } void blk_rq_stat_add(struct blk_rq_stat *, u64); -void blk_rq_stat_sum(struct blk_rq_stat *, struct blk_rq_stat *); +void blk_rq_stat_collect(struct blk_rq_stat *dst, struct blk_rq_stat *src); +void blk_rq_stat_merge(struct blk_rq_stat *dst, struct blk_rq_stat *src); void blk_rq_stat_init(struct blk_rq_stat *); #endif -- 2.22.0