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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 B68F7C433F5 for ; Wed, 8 Sep 2021 02:59:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1ACC61153 for ; Wed, 8 Sep 2021 02:59:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345895AbhIHDBB (ORCPT ); Tue, 7 Sep 2021 23:01:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:59046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347322AbhIHDA5 (ORCPT ); Tue, 7 Sep 2021 23:00:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B005361102; Wed, 8 Sep 2021 02:59:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1631069989; bh=LSZnqdKr26eTreoRKsmvAbakBcOQrQwUjMLtOIxvhd0=; h=Date:From:To:Subject:In-Reply-To:From; b=GNtKwPHejKgiZTQDsEow+krpINbSCSNS46HDhVEXLG0+FpVnQBJRoyVw5/5wjcm28 rBywGPuhI81t8k9vSs3kcL9P0MWaasM3McBSvCsCEs3NXaE9k3WgjmSAsngHMOvQvd AnsgVSY79xeL4rGtKBshpLkLrpWkFsoKdnYh6g1E= Date: Tue, 07 Sep 2021 19:59:48 -0700 From: Andrew Morton To: aklimov@redhat.com, akpm@linux-foundation.org, alobakin@pm.me, andriy.shevchenko@linux.intel.com, dennis@kernel.org, jolsa@redhat.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, ulf.hansson@linaro.org, will@kernel.org, wsa+renesas@sang-engineering.com, yury.norov@gmail.com Subject: [patch 123/147] vsprintf: rework bitmap_list_string Message-ID: <20210908025948.a-7N5QB_n%akpm@linux-foundation.org> In-Reply-To: <20210907195226.14b1d22a07c085b22968b933@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yury Norov Subject: vsprintf: rework bitmap_list_string bitmap_list_string() is very ineffective when printing bitmaps with long ranges of set bits because it calls find_next_bit for each bit in the bitmap. We can do better by detecting ranges of set bits. In my environment, before/after is 943008/31008 ns. [yury.norov@gmail.com: don't increment buf in bitmap_list_string] Link: https://lkml.kernel.org/r/20210817193735.269942-1-yury.norov@gmail.com Link: https://lkml.kernel.org/r/20210814211713.180533-18-yury.norov@gmail.com Signed-off-by: Yury Norov Tested-by: Wolfram Sang Cc: Alexander Lobakin Cc: Alexey Klimov Cc: Andy Shevchenko Cc: Dennis Zhou Cc: Jiri Olsa Cc: Ulf Hansson Cc: Will Deacon Signed-off-by: Andrew Morton --- lib/vsprintf.c | 24 +++++++----------------- 1 file changed, 7 insertions(+), 17 deletions(-) --- a/lib/vsprintf.c~vsprintf-rework-bitmap_list_string +++ a/lib/vsprintf.c @@ -1241,20 +1241,13 @@ char *bitmap_list_string(char *buf, char struct printf_spec spec, const char *fmt) { int nr_bits = max_t(int, spec.field_width, 0); - /* current bit is 'cur', most recently seen range is [rbot, rtop] */ - int cur, rbot, rtop; bool first = true; + int rbot, rtop; if (check_pointer(&buf, end, bitmap, spec)) return buf; - rbot = cur = find_first_bit(bitmap, nr_bits); - while (cur < nr_bits) { - rtop = cur; - cur = find_next_bit(bitmap, nr_bits, cur + 1); - if (cur < nr_bits && cur <= rtop + 1) - continue; - + for_each_set_bitrange(rbot, rtop, bitmap, nr_bits) { if (!first) { if (buf < end) *buf = ','; @@ -1263,15 +1256,12 @@ char *bitmap_list_string(char *buf, char first = false; buf = number(buf, end, rbot, default_dec_spec); - if (rbot < rtop) { - if (buf < end) - *buf = '-'; - buf++; - - buf = number(buf, end, rtop, default_dec_spec); - } + if (rtop == rbot + 1) + continue; - rbot = cur; + if (buf < end) + *buf = '-'; + buf = number(buf + 1, end, rtop - 1, default_dec_spec); } return buf; } _