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=-12.8 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 999A3C07E96 for ; Thu, 15 Jul 2021 15:50:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CB6E613CF for ; Thu, 15 Jul 2021 15:50:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239199AbhGOPxS (ORCPT ); Thu, 15 Jul 2021 11:53:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238841AbhGOPxR (ORCPT ); Thu, 15 Jul 2021 11:53:17 -0400 Received: from mail-qt1-x82b.google.com (mail-qt1-x82b.google.com [IPv6:2607:f8b0:4864:20::82b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7269FC06175F for ; Thu, 15 Jul 2021 08:50:24 -0700 (PDT) Received: by mail-qt1-x82b.google.com with SMTP id d1so4852898qto.4 for ; Thu, 15 Jul 2021 08:50:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=zdJ5ZjcavwcHHbMqn+hbi9ZtU6+DEG5Y1d3HPh4pGFc=; b=d2L/sE9pxIM+mizWsal43cYbqpELvR3/1xAUM1YqHB2Ah++CRoBLk7d3Tfl7QTJGCs ZtuvUQMiZGzWEsVRHb5CHEkz3r1gmTOtBkKoL48BGULgS30KkA4H50wEhE3oXX2bwMT2 tJwZpzSfe0Av6bP6wUSZtYi+NV3wMjoso/T4a91IpCmArB0gR0Lw1e5adE7eOFG7taGu 2rDH/K/h8URg73xUHe/rn8m2AIWAzZGLo6MAbwQ3R14e8Dr97hGTYiiA/38g4NtauX8X 5wKraclDzqmdp3vzXHqJhfyZ/N9LBBs8jA9Oz3/bRBH3ErMSV9sQs2nglWfhsYpsyoS0 XqZg== 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:references :mime-version:content-disposition:in-reply-to; bh=zdJ5ZjcavwcHHbMqn+hbi9ZtU6+DEG5Y1d3HPh4pGFc=; b=rUMqb3Iz0pc3okvHafMUX+fAqlc9qoKEuky+PCmga4xXCCW2viGpaUleL7+ffP2ptF vwHL84IjJ0cZPd+EEO4qGHg/OKnNsMxpD2FojuwI/L2r29FwksYokfkIK15m1RItk7fl qXWbGX35LSVUi0YIu472HbFekSGs7UXuyRk+b9nItP9LkAv+KAAjviqEIqaZuGO+ZzIM uKA6ehJS1Sx5tct8H6flizUzGXhuszGGVJLJn6t0y9haWCE+1r0y5L3VBsezifcaZilv DXbjYPTGM2Gt434UMtZAT1L4MK9nD3wNXAaja4xAcAWeHSSIo2Aeyqul/NRto/YU5uAa Ytgw== X-Gm-Message-State: AOAM5302i6nTxKDylOhwi4BXmbYj/3PsrivMV3uepXSAFqEuztexeoVL uGL3qUpzurmAVxsh8HvMjx4= X-Google-Smtp-Source: ABdhPJxqTexUkfy/+clU20gVzdJQ2zM0BLKh1Lmpydjsv2w3mO6pcXgZudwaDWgCC3bQsleiViXDCg== X-Received: by 2002:ac8:1005:: with SMTP id z5mr4641488qti.255.1626364222971; Thu, 15 Jul 2021 08:50:22 -0700 (PDT) Received: from localhost ([207.98.216.60]) by smtp.gmail.com with ESMTPSA id j20sm2115806qtq.14.2021.07.15.08.50.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Jul 2021 08:50:22 -0700 (PDT) Date: Thu, 15 Jul 2021 08:50:21 -0700 From: Yury Norov To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Andy Shevchenko , Rasmus Villemoes , Petr Mladek , Sergey Senozhatsky , Tejun Heo Subject: Re: [PATCH 2/2] bitmap: introduce for_each_set_bitrange Message-ID: References: <20210709034519.2859777-1-yury.norov@gmail.com> <20210709034519.2859777-3-yury.norov@gmail.com> <20210709095950.6a451ccb@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210709095950.6a451ccb@oasis.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 09, 2021 at 09:59:50AM -0400, Steven Rostedt wrote: > On Thu, 8 Jul 2021 20:45:19 -0700 > Yury Norov wrote: > > > bitmap_list_string() is very ineffective when printing bitmaps with long > > ranges of set bits because it calls find_next_bit for each bit. We can do > > better by detecting ranges of set bits. > > > > This patch introduces a macro for_each_set_bitrange and uses it in > > bitmap_list_string(). In my environment, before/after is 943008/31008 ns. > > > > Signed-off-by: Yury Norov > > --- > > include/linux/find.h | 7 +++++++ > > lib/vsprintf.c | 40 ++++++++++++++++------------------------ > > 2 files changed, 23 insertions(+), 24 deletions(-) > > > > diff --git a/include/linux/find.h b/include/linux/find.h > > index ae9ed52b52b8..1a5ed45dc81b 100644 > > --- a/include/linux/find.h > > +++ b/include/linux/find.h > > @@ -301,6 +301,13 @@ unsigned long find_next_bit_le(const void *addr, unsigned > > (bit) < (size); \ > > (bit) = find_next_zero_bit((addr), (size), (bit) + 1)) > > > > +#define for_each_set_bitrange(b, e, addr, size) \ > > The above needs a kerneldoc header. OK. > > > + for ((b) = find_next_bit((addr), (size), 0), \ > > + (e) = find_next_zero_bit((addr), (size), (b) + 1); \ > > + (b) < (size); \ > > + (b) = find_next_bit((addr), (size), (e) + 1), \ > > + (e) = find_next_zero_bit((addr), (size), (b) + 1)) > > + > > /** > > * for_each_set_clump8 - iterate over bitmap for each 8-bit clump with set bits > > * @start: bit offset to start search and to store the current iteration offset > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > > index 87acf66f0e4c..1ee54dace71e 100644 > > --- a/lib/vsprintf.c > > +++ b/lib/vsprintf.c > > @@ -1240,38 +1240,30 @@ char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap, > > 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; > > + char *start = buf; > > + int b, e; > > > > 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(b, e, bitmap, nr_bits) { > > + buf = number(buf, end, b, default_dec_spec); > > + if (e == b + 1) > > + goto put_comma; > > Using a goto to skip a few lines instead of just having the reverse > conditional is rather sloppy IMO. > > if (e != b + 1) { > if (buf < end) > *buf = '-'; > buf++; > buf = number(buf, end, e - 1, default_dec_spec); > } > > Is much clearer. I don't think it's clearer, but as you wish. > > > > - if (!first) { > > - if (buf < end) > > - *buf = ','; > > - buf++; > > - } > > - first = false; > > + if (buf < end) > > + *buf = '-'; > > > > - buf = number(buf, end, rbot, default_dec_spec); > > - if (rbot < rtop) { > > - if (buf < end) > > - *buf = '-'; > > - buf++; > > + buf = number(++buf, end, e - 1, default_dec_spec); > > +put_comma: > > + if (buf < end) > > + *buf = ','; > > + buf++; > > + } > > > > - buf = number(buf, end, rtop, default_dec_spec); > > - } > > + if (buf > start) > > + buf--; > > If the above is to undo the last comma, please put back the first logic. > > -- Steve You're asking me to move part of the logic inside the loop which generally should be avoided. Is there any particular reason to do this? > > > > > - rbot = cur; > > - } > > return buf; > > } > >