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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 ECAB3C4361B for ; Fri, 11 Dec 2020 08:52:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B490E23F34 for ; Fri, 11 Dec 2020 08:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405551AbgLKIv6 (ORCPT ); Fri, 11 Dec 2020 03:51:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403782AbgLKIv1 (ORCPT ); Fri, 11 Dec 2020 03:51:27 -0500 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BCF6C0613D3 for ; Fri, 11 Dec 2020 00:50:47 -0800 (PST) Received: by mail-pf1-x444.google.com with SMTP id t8so6588962pfg.8 for ; Fri, 11 Dec 2020 00:50:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=u7JMQZvgEid85bk0GRu+K67PTTlqfUvEzJX5XdyMvGY=; b=Z9f6tLQdp5fCaD6n/7Ur4nGvTRVEFx2v/Toe16VwLUVIWZ+5kvYWvHCoFj0gOTK4Sy eroHC2dDh2sAeJhFHNdLUZuf21OvuhqgQGLgAywB9cHnHEzyzASqUzbZhbUCl1a6OwIB Lz70OpRDOGZ90/V/f0ysDRV3XlB2S+rN+vNaN/F9uYcDuQ/5Hbk7jg+CUMtm1mkh06s/ ACMDMJtdHAA0qNBJFeBLSaUcTlxUEuSFXjdEESWr6ss9sxdoY4SPSuKK/hJq/oy39gFc iy9MX8U3MHdxq20mvr48Vo0r6HnoPr7BajjqHb0FThJvTZTvkeTQpxZgFxRrMwZ7aC8B YmaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=u7JMQZvgEid85bk0GRu+K67PTTlqfUvEzJX5XdyMvGY=; b=qoTpazY85MTHa/9fatOtQpUulPzHsvzk/Epo5hDM6B0aiqR5V1dKdV8qDuA7gXL7t6 brXSN3YrjC1W92k8TjFLa+Bx0SDO81syzSDia01LD1h19NdCBx2fC649Z32Mtk5bCR+/ qaeJDYD8vJhOtB1+xUTqCoNWX6Uwnmkq7cytfJbjpSA4eyDV2k1AVhZrTALSFd3tKmkH CW4YQ/DSlG6a9+8AjsTCdwV3F3Q7CGev4IkY/zV2Y7A1Ew3kZ0AlmedqLiXABCzj8j1D I1jf0e4mDtS59puBZqMmW81vqygANyqEAO6e6026eVVOPdfVqdcd64Szi7mbISikGjav 4r4A== X-Gm-Message-State: AOAM530OhduQmugJxMK9wlxFkD2Atl+/bbGRcVcnbdSyi1aLCmOJ52dN oC1kCPVcaxFtw6U0UJfyTR4= X-Google-Smtp-Source: ABdhPJxZGCPgoXMVSDU7P4uxq956WQzvkQ//3O/oyEGZjNcQA086pt1QTGOfPUVyxxJKZiPJtD3YlA== X-Received: by 2002:a62:1b16:0:b029:19e:238:8627 with SMTP id b22-20020a621b160000b029019e02388627mr3884431pfb.52.1607676646528; Fri, 11 Dec 2020 00:50:46 -0800 (PST) Received: from ubuntu ([125.132.45.8]) by smtp.gmail.com with ESMTPSA id e3sm8754901pfe.154.2020.12.11.00.50.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Dec 2020 00:50:45 -0800 (PST) Date: Fri, 11 Dec 2020 17:50:39 +0900 From: Levi Yun To: dushistov@mail.ru, arnd@arndb.de, akpm@linux-foundation.org, gustavo@embeddedor.com, vilhelm.gray@gmail.com, richard.weiyang@linux.alibaba.com, andriy.shevchenko@linux.intel.com, joseph.qi@linux.alibaba.com, skalluru@marvell.com, yury.norov@gmail.com, jpoimboe@redhat.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH] lib/find_bit_bench: fix the unmatched iterations cnt Message-ID: <20201211085039.GA7619@ubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We should have same iteration count when we walk the same bitmap regardless of using find_next_bit or find_last_bit. When we run the find_bit_benchmark.ko, we sometime get unmatched iterations count below: Start testing find_bit() with random-filled bitmap [+...] find_next_bit: 875085 ns, 163755 iterations < [+...] find_next_zero_bit: 865319 ns, 163926 iterations [+...] find_last_bit: 611807 ns, 163756 iterations < [+...] find_first_bit: 1601016 ns, 16335 iterations [+...] find_next_and_bit: 400645 ns, 74040 iterations [+...] Start testing find_bit() with sparse bitmap [+...] find_next_bit: 9942 ns, 654 iterations [+...] find_next_zero_bit: 1678445 ns, 327027 iterations [+...] find_last_bit: 7131 ns, 654 iterations [+...] find_first_bit: 551383 ns, 654 iterations [+...] find_next_and_bit: 3027 ns, 1 iterations Normally, this is happen when the last bit of bitmap was set. This patch fix the unmatched iterations count between test_find_next_bit and test_find_last_bit. Signed-off-by: Levi Yun --- lib/find_bit_benchmark.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c index 5637c5711db9..766e0487852b 100644 --- a/lib/find_bit_benchmark.c +++ b/lib/find_bit_benchmark.c @@ -35,14 +35,14 @@ static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata; */ static int __init test_find_first_bit(void *bitmap, unsigned long len) { - unsigned long i, cnt; + unsigned long i = 0, cnt = 0; ktime_t time; time = ktime_get(); - for (cnt = i = 0; i < len; cnt++) { + do { i = find_first_bit(bitmap, len); __clear_bit(i, bitmap); - } + } while (i++ < len && ++cnt); time = ktime_get() - time; pr_err("find_first_bit: %18llu ns, %6ld iterations\n", time, cnt); @@ -51,12 +51,13 @@ static int __init test_find_first_bit(void *bitmap, unsigned long len) static int __init test_find_next_bit(const void *bitmap, unsigned long len) { - unsigned long i, cnt; + unsigned long i = 0, cnt = 0; ktime_t time; time = ktime_get(); - for (cnt = i = 0; i < BITMAP_LEN; cnt++) - i = find_next_bit(bitmap, BITMAP_LEN, i) + 1; + do { + i = find_next_bit(bitmap, BITMAP_LEN, i); + } while (i++ < BITMAP_LEN && ++cnt); time = ktime_get() - time; pr_err("find_next_bit: %18llu ns, %6ld iterations\n", time, cnt); @@ -65,12 +66,13 @@ static int __init test_find_next_bit(const void *bitmap, unsigned long len) static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len) { - unsigned long i, cnt; + unsigned long i = 0, cnt = 0; ktime_t time; time = ktime_get(); - for (cnt = i = 0; i < BITMAP_LEN; cnt++) - i = find_next_zero_bit(bitmap, len, i) + 1; + do { + i = find_next_zero_bit(bitmap, len, i); + } while (i++ < BITMAP_LEN && ++cnt); time = ktime_get() - time; pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt); @@ -84,12 +86,11 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long len) time = ktime_get(); do { - cnt++; l = find_last_bit(bitmap, len); if (l >= len) break; len = l; - } while (len); + } while (len >= 0 && ++cnt); time = ktime_get() - time; pr_err("find_last_bit: %18llu ns, %6ld iterations\n", time, cnt); @@ -99,12 +100,13 @@ static int __init test_find_last_bit(const void *bitmap, unsigned long len) static int __init test_find_next_and_bit(const void *bitmap, const void *bitmap2, unsigned long len) { - unsigned long i, cnt; + unsigned long i = 0, cnt = 0; ktime_t time; time = ktime_get(); - for (cnt = i = 0; i < BITMAP_LEN; cnt++) - i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1); + do { + i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i); + } while (i++ < BITMAP_LEN && ++cnt); time = ktime_get() - time; pr_err("find_next_and_bit: %18llu ns, %6ld iterations\n", time, cnt); -- 2.27.0