From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28478 invoked by alias); 13 Jan 2018 10:48:45 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 28464 invoked by uid 89); 13 Jan 2018 10:48:45 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.6 required=5.0 tests=AWL,BAYES_00,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=no version=3.3.2 spammy=assist X-HELO: mail-it0-f48.google.com Received: from mail-it0-f48.google.com (HELO mail-it0-f48.google.com) (209.85.214.48) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sat, 13 Jan 2018 10:48:43 +0000 Received: by mail-it0-f48.google.com with SMTP id u62so11895055ita.2 for ; Sat, 13 Jan 2018 02:48:43 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=AefSvWg6gHogW8P2Jle9wbRQH29/SVw98qjQigibev0=; b=gBkUju06f2rTSycpJejmka0YaMIFjOOBq6UwuevCQwqWwYmzb1heqFBUWy/x9sdAxj It0cj3TDMIPRLivo8nAyTocAj8LkZ50wpw+vlEhtajuI2xfkqlJiAx8Kp1v/o43TDnt8 fUJCHpy4WKGQCbXsnhur/0YZO2tclhik2xP79J6rdFCIdTTy0j6PPqeItt2hG4xOwkgm ZDwcCoxiq/LQb8s4FOAry229A63LYWOKb4sgP9IUOwSvCqRa6so9UJVr4GmlCSQYxSDW 5l8jd2DJ3tgfHpfJVkwLbnwfyZs1FRVY/Tbq/ze6XnGwRnKUNw8R1ho3ucOkKrHz1jfr /Liw== X-Gm-Message-State: AKwxytc27tIWz8RomW3RqP0In0G/rj/gmXkDRZmYHrmCCKUttDt2yVwL gKa/9h2EBiEeIHXfFCwPZaETkZF/Bj/xJALzPsM= X-Google-Smtp-Source: ACJfBov2XBN9jWAfrWKjEjVKMUnVg52kfwKiCcQcMZpbvpT63/garaqsRKKoFbsFNgaj3Hk5mAx8Xj2tzaFlntKqEnA= X-Received: by 10.36.58.11 with SMTP id m11mr7146012itm.89.1515840521729; Sat, 13 Jan 2018 02:48:41 -0800 (PST) MIME-Version: 1.0 Received: by 10.79.147.218 with HTTP; Sat, 13 Jan 2018 02:48:40 -0800 (PST) In-Reply-To: <3acfae95-e62b-40d5-d094-44e651dd6b79@gmail.com> References: <46515148-9f8e-6eae-69f9-9bf20921097a@t-online.de> <20180112143339.GE24623@calimero.vinschen.de> <20180112204149.GF24623@calimero.vinschen.de> <3acfae95-e62b-40d5-d094-44e651dd6b79@gmail.com> From: Lee Date: Sat, 13 Jan 2018 10:48:00 -0000 Message-ID: Subject: Re: calloc speed difference To: cygwin@cygwin.com Content-Type: text/plain; charset="UTF-8" X-IsSubscribed: yes X-SW-Source: 2018-01/txt/msg00133.txt.bz2 On 1/12/18, cyg Simple wrote: > On 1/12/2018 3:41 PM, Corinna Vinschen wrote: >> On Jan 12 14:59, cyg Simple wrote: >>> On 1/12/2018 9:33 AM, Corinna Vinschen wrote: >>>> On Jan 12 15:06, Christian Franke wrote: >>>>> Timing [cm]alloc() calls without actually using the allocated memory >>>>> might >>>>> produce misleading results due to lazy page allocation and/or >>>>> zero-filling. >>>>> >>>>> MinGW binaries use calloc() from msvcrt.dll. This calloc() does not >>>>> call >>>>> malloc() and then memset(). It directly calls: >>>>> >>>>> mem = HeapAlloc(_crtheap, HEAP_ZERO_MEMORY, size); >>>>> >>>>> which possibly only reserves allocate-and-zero-fill-on-demand pages >>>>> for >>>>> later. >>>>> >>>>> Cygwin's calloc() is different. >>>> >>>> But then again, Cygwin's malloc *is* slow, particulary in >>>> memory-demanding multi-threaded scenarios since that serializes all >>>> malloc/free calls. >>>> >>>> The memory handling within Cygwin is tricky. Attempts to replace good >>>> old dlmalloc with a fresher jemalloc or ptmalloc failed, but that only >>>> means the developer (i.e., me, in case of ptmalloc) was too lazy... >>>> busy! I mean busy... to pull this through. >>>> >>>> Having said that, if somebody would like to take a stab at replacing >>>> dlmalloc with something leaner, I would be very happy and assist as >>>> much as I can. >>> >>> Corina, how reliable is the Cygwin time function on a non-Cygwin >>> executable? Isn't this a comparison of apples to oranges? The wall-clock time seems reliable. Timing a non-Cygwin executable gives you 0.0 for the user & sys categories but I don't care about them anywhere near as much as how long it takes for the program to run. >> I wasn't comparing, in fact. I was just saying that Cygwin's malloc >> is slow, partially because dlmalloc is not the fastest one, partially >> due to the serialization overhead in multithreading scenarios. > > No, but the OP *is* doing a compare. From what I remember doing a time > comparison of a non-Cygwin app compared to a Cygwin app isn't really a > logical comparison. I'm probably missing something, but.. I have the source code. I have the choice of using the cygwin gcc compiler or the mingw cross compiler. If both executables produce the same results then comparing execution times seems perfectly valid. On the other hand, if the program produces text output (ie. dos vs. unix line endings) then dealing with dos line endings in the cygwin environment might be enough of a pain that I accept the ease-of-use vs. execution time tradeoff and keep everything compatible w/ cygwin. > Even if the two were a Cygwin app multiple runs of > the same app will show variance. But not the seconds vs. minutes difference that I occasionally see when comparing cygwin vs. native app performance. Regards, Lee -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple