From patchwork Sat Oct 7 00:55:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaohua Li X-Patchwork-Id: 9990971 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id ADDE4603FA for ; Sat, 7 Oct 2017 00:56:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9FA9928C6A for ; Sat, 7 Oct 2017 00:56:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9427F28D96; Sat, 7 Oct 2017 00:56:26 +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=-6.9 required=2.0 tests=BAYES_00,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 38CC428C6A for ; Sat, 7 Oct 2017 00:56:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752461AbdJGA4Z (ORCPT ); Fri, 6 Oct 2017 20:56:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:55104 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752191AbdJGA4Y (ORCPT ); Fri, 6 Oct 2017 20:56:24 -0400 Received: from shli-virt.localdomain (unknown [199.201.64.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D335F21908; Sat, 7 Oct 2017 00:56:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D335F21908 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=fail smtp.mailfrom=shli@fb.com From: Shaohua Li To: linux-block@vger.kernel.org Cc: vgoyal@redhat.com, tj@kernel.org, axboe@kernel.dk, Kernel-team@fb.com, Shaohua Li , Omar Sandoval Subject: [PATCH V2 1/3] blk-stat: delete useless code Date: Fri, 6 Oct 2017 17:55:59 -0700 Message-Id: <74821887899a7d05c6429e03f0dc49a079c446b9.1507337347.git.shli@fb.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: References: In-Reply-To: References: 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 From: Shaohua Li Fix two issues: - the per-cpu stat flush is unnecessary, nobody uses per-cpu stat except sum it to global stat. We can do the calculation there. The flush just wastes cpu time. - some fields are signed int/s64. I don't see the point. Cc: Omar Sandoval Signed-off-by: Shaohua Li Reviewed-by: Omar Sandoval --- block/blk-stat.c | 45 +++++++-------------------------------------- include/linux/blk_types.h | 5 ++--- 2 files changed, 9 insertions(+), 41 deletions(-) diff --git a/block/blk-stat.c b/block/blk-stat.c index c52356d..3a2f3c9 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -11,8 +11,6 @@ #include "blk-mq.h" #include "blk.h" -#define BLK_RQ_STAT_BATCH 64 - struct blk_queue_stats { struct list_head callbacks; spinlock_t lock; @@ -23,45 +21,21 @@ static void blk_stat_init(struct blk_rq_stat *stat) { stat->min = -1ULL; stat->max = stat->nr_samples = stat->mean = 0; - stat->batch = stat->nr_batch = 0; -} - -static void blk_stat_flush_batch(struct blk_rq_stat *stat) -{ - const s32 nr_batch = READ_ONCE(stat->nr_batch); - const s32 nr_samples = READ_ONCE(stat->nr_samples); - - if (!nr_batch) - return; - if (!nr_samples) - stat->mean = div64_s64(stat->batch, nr_batch); - else { - stat->mean = div64_s64((stat->mean * nr_samples) + - stat->batch, - nr_batch + nr_samples); - } - - stat->nr_samples += nr_batch; - stat->nr_batch = stat->batch = 0; + stat->batch = 0; } +/* src is a per-cpu stat, mean isn't initialized */ static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) { - blk_stat_flush_batch(src); - if (!src->nr_samples) return; dst->min = min(dst->min, src->min); dst->max = max(dst->max, src->max); - if (!dst->nr_samples) - dst->mean = src->mean; - else { - dst->mean = div64_s64((src->mean * src->nr_samples) + - (dst->mean * dst->nr_samples), - dst->nr_samples + src->nr_samples); - } + dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples, + dst->nr_samples + src->nr_samples); + dst->nr_samples += src->nr_samples; } @@ -69,13 +43,8 @@ static void __blk_stat_add(struct blk_rq_stat *stat, u64 value) { stat->min = min(stat->min, value); stat->max = max(stat->max, value); - - if (stat->batch + value < stat->batch || - stat->nr_batch + 1 == BLK_RQ_STAT_BATCH) - blk_stat_flush_batch(stat); - stat->batch += value; - stat->nr_batch++; + stat->nr_samples++; } void blk_stat_add(struct request *rq) @@ -84,7 +53,7 @@ void blk_stat_add(struct request *rq) struct blk_stat_callback *cb; struct blk_rq_stat *stat; int bucket; - s64 now, value; + u64 now, value; now = __blk_stat_time(ktime_to_ns(ktime_get())); if (now < blk_stat_time(&rq->issue_stat)) diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index a2d2aa7..3385c89 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -329,11 +329,10 @@ static inline bool blk_qc_t_is_internal(blk_qc_t cookie) } struct blk_rq_stat { - s64 mean; + u64 mean; u64 min; u64 max; - s32 nr_samples; - s32 nr_batch; + u32 nr_samples; u64 batch; };