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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09620C38142 for ; Sat, 28 Jan 2023 19:55:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234551AbjA1Tz0 (ORCPT ); Sat, 28 Jan 2023 14:55:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234507AbjA1TzY (ORCPT ); Sat, 28 Jan 2023 14:55:24 -0500 Received: from mail-qk1-x735.google.com (mail-qk1-x735.google.com [IPv6:2607:f8b0:4864:20::735]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85D47234D6 for ; Sat, 28 Jan 2023 11:55:22 -0800 (PST) Received: by mail-qk1-x735.google.com with SMTP id l1so3753321qkg.11 for ; Sat, 28 Jan 2023 11:55:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=qbp9QaNDZWJkPD4EX8FVMT1Tf9hwMQACYdEjENlwtsU=; b=aClggjBpSo0dFaEaJIufElfuIIXiVg48b4HEDmAU9Il3GXJe+8V6hwT1wUFfqXfdi+ QJghwDrMoX3LSPAixk1mbpVtS1vBSfdUDMwOU0T+WbZwOyiUjg4d7VI38XTuPhEzouhS GuTXr/D3Yp57OOflAFovkJwzpHbWPs5lId27yXFOl+PRX5IrlxURaHI8w3JYfBEUdC7F gRCdW2D4XrTfvLFJi+nowL6UO8ALsK8FRylc13hULqLYwEeggUJTYWDZo+6W/3qunTv1 oy83Jwo/QRnEOAfDKzFdKabhSVlk/tusu0JNQMYpLmMrk71juj0ZX0gFOP3vhrTCwzUe zP3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=qbp9QaNDZWJkPD4EX8FVMT1Tf9hwMQACYdEjENlwtsU=; b=aa2mqGhszkYk8yybB8T7qwfGXiz6eGIrwvK0XCHVC4af8IPr6g6YqzVxX/SfMycAG3 xvlv/ZLP08quXJ8DoOPRZ6lE7uhTAqyp/H/dfWHFTHdQt8nuEPiGcIE0degh1SxGe+Br DeugnQ3CRVmymQaG73OVw+R7c5YMzk4qZA2hrFajq8v0ZGW8Xl0Ku+YvDPl4KC9WQg8v nJu47StyNhK6kszKA59OSIAgJ9YYy/cJlflgwaZ7rHC5EMTCnmAsGQjhsvhdKGOZvBLa JcrbIszXU3Al3xRQSaqqLkOKNGULCuc+WMzEf4nqt/Kl5Ba5XjmaMb61Fuu+K4gwhxii C8qQ== X-Gm-Message-State: AFqh2kqPCVxyKVaj/ZrRzh0h85KNWIFdI+W07bQKv61VsI5Gqa4HXhe8 9c/k5SkNpl7WkGDexizBrnarLoLrB+rh/5kagyY= X-Google-Smtp-Source: AMrXdXvJYwjhNwl80QknzB3ZE1bCEaEDhrhA/Qx3wY0ugJWoV/QT87p/6OXwoI6XIXEVhqsU5luZvzFSw2T9CRYwt8Q= X-Received: by 2002:a05:620a:1214:b0:706:9677:5fdd with SMTP id u20-20020a05620a121400b0070696775fddmr3008606qkj.283.1674935721101; Sat, 28 Jan 2023 11:55:21 -0800 (PST) MIME-Version: 1.0 References: <20230127155135.27153-1-andriy.shevchenko@linux.intel.com> In-Reply-To: From: Andy Shevchenko Date: Sat, 28 Jan 2023 21:54:44 +0200 Message-ID: Subject: Re: [PATCH v1 1/1] lib/string: Use strchr() in strpbrk() To: David Laight Cc: Andy Shevchenko , Kees Cook , "linux-kernel@vger.kernel.org" , Andy Shevchenko , Rasmus Villemoes , Andrew Morton Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 28, 2023 at 4:51 PM David Laight wrote: > > From: Andy Shevchenko > > Sent: 27 January 2023 15:52 > > > > Use strchr() instead of open coding it as it's done elsewhere in > > the same file. Either we will have similar to what it was or possibly > > better performance in case architecture implements its own strchr(). > > Except that you get a whole load of calls to strchr() for (typically) > very few characters. > So the cost of the calls dominates, anything that tries to speed up > strchr() for long strings will also slow things down. Hmm... I haven't seen the calls, I assume gcc simply inlined a copy of that. ... > Although I very much doubt strpbrk() is used anywhere where > performance matters. strsep()/strspn() are the users. -- With Best Regards, Andy Shevchenko